OpenCloudOS-Kernel/lib/Kconfig.debug

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menu "printk and dmesg options"
config PRINTK_TIME
bool "Show timing information on printks"
depends on PRINTK
help
Selecting this option causes time stamps of the printk()
messages to be added to the output of the syslog() system
call and at the console.
The timestamp is always recorded internally, and exported
to /dev/kmsg. This flag just specifies if the timestamp should
be included, not that the timestamp is recorded.
The behavior is also controlled by the kernel command line
parameter printk.time=1. See Documentation/kernel-parameters.txt
config MESSAGE_LOGLEVEL_DEFAULT
int "Default message log level (1-7)"
range 1 7
default "4"
help
Default log level for printk statements with no specified priority.
This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
that are auditing their logs closely may want to set it to a lower
priority.
config BOOT_PRINTK_DELAY
bool "Delay each boot printk message by N milliseconds"
depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
help
This build option allows you to read kernel boot messages
by inserting a short delay after each one. The delay is
specified in milliseconds on the kernel command line,
using "boot_delay=N".
It is likely that you would also need to use "lpj=M" to preset
the "loops per jiffie" value.
See a previous boot log for the "lpj" value to use for your
system, and then set "lpj=M" before setting "boot_delay=N".
NOTE: Using this option may adversely affect SMP systems.
I.e., processors other than the first one may not boot up.
BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
what it believes to be lockup conditions.
config DYNAMIC_DEBUG
bool "Enable dynamic printk() support"
default n
depends on PRINTK
depends on DEBUG_FS
help
Compiles debug level messages into the kernel, which would not
otherwise be available at runtime. These messages can then be
enabled/disabled based on various levels of scope - per source file,
function, module, format string, and line number. This mechanism
implicitly compiles in all pr_debug() and dev_dbg() calls, which
enlarges the kernel text size by about 2%.
If a source file is compiled with DEBUG flag set, any
pr_debug() calls in it are enabled by default, but can be
disabled at runtime as below. Note that DEBUG flag is
turned on by many CONFIG_*DEBUG* options.
Usage:
Dynamic debugging is controlled via the 'dynamic_debug/control' file,
which is contained in the 'debugfs' filesystem. Thus, the debugfs
filesystem must first be mounted before making use of this feature.
We refer the control file as: <debugfs>/dynamic_debug/control. This
file contains a list of the debug statements that can be enabled. The
format for each line of the file is:
filename:lineno [module]function flags format
filename : source file of the debug statement
lineno : line number of the debug statement
module : module that contains the debug statement
function : function that contains the debug statement
flags : '=p' means the line is turned 'on' for printing
format : the format used for the debug statement
From a live system:
nullarbor:~ # cat <debugfs>/dynamic_debug/control
# filename:lineno [module]function flags format
fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
Example usage:
// enable the message at line 1603 of file svcsock.c
nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
<debugfs>/dynamic_debug/control
// enable all the messages in file svcsock.c
nullarbor:~ # echo -n 'file svcsock.c +p' >
<debugfs>/dynamic_debug/control
// enable all the messages in the NFS server module
nullarbor:~ # echo -n 'module nfsd +p' >
<debugfs>/dynamic_debug/control
// enable all 12 messages in the function svc_process()
nullarbor:~ # echo -n 'func svc_process +p' >
<debugfs>/dynamic_debug/control
// disable all 12 messages in the function svc_process()
nullarbor:~ # echo -n 'func svc_process -p' >
<debugfs>/dynamic_debug/control
See Documentation/dynamic-debug-howto.txt for additional information.
endmenu # "printk and dmesg options"
menu "Compile-time checks and compiler options"
config DEBUG_INFO
bool "Compile the kernel with debug info"
depends on DEBUG_KERNEL && !COMPILE_TEST
help
If you say Y here the resulting kernel image will include
debugging info resulting in a larger kernel image.
This adds debug symbols to the kernel and modules (gcc -g), and
is needed if you intend to use kernel crashdump or binary object
tools like crash, kgdb, LKCD, gdb, etc on the kernel.
Say Y here only if you plan to debug the kernel.
If unsure, say N.
config DEBUG_INFO_REDUCED
bool "Reduce debugging information"
depends on DEBUG_INFO
help
If you say Y here gcc is instructed to generate less debugging
information for structure types. This means that tools that
need full debugging information (like kgdb or systemtap) won't
be happy. But if you merely need debugging information to
resolve line numbers there is no loss. Advantage is that
build directory object sizes shrink dramatically over a full
DEBUG_INFO build and compile times are reduced too.
Only works with newer gcc versions.
kbuild: Support split debug info v4 This is an alternative approach to lower the overhead of debug info (as we discussed a few days ago) gcc 4.7+ and newer binutils have a new "split debug info" debug info model where the debug info is only written once into central ".dwo" files. This avoids having to copy it around multiple times, from the object files to the final executable. It lowers the disk space requirements. In addition it defaults to compressed debug data. More details here: http://gcc.gnu.org/wiki/DebugFission This patch adds a new option to enable it. It has to be an option, because it'll undoubtedly break everyone's debuginfo packaging scheme. gdb/objdump/etc. all still work, if you have new enough versions. I don't see big compile wins (maybe a second or two faster or so), but the object dirs with debuginfo get significantly smaller. My standard kernel config (slightly bigger than defconfig) shrinks from 2.9G disk space to 1.1G objdir (with non reduced debuginfo). I presume if you are IO limited the compile time difference will be larger. Only problem I've seen so far is that it doesn't play well with older versions of ccache (apparently fixed, see https://bugzilla.samba.org/show_bug.cgi?id=10005) v2: various fixes from Dirk Gouders. Improve commit message slightly. v3: Fix clean rules and improve Kconfig slightly v4: Fix merge error in last version (Sam Ravnborg) Clarify description that it mainly helps disk size. Cc: Dirk Gouders <dirk@gouders.net> Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Michal Marek <mmarek@suse.cz>
2014-07-31 02:50:18 +08:00
config DEBUG_INFO_SPLIT
bool "Produce split debuginfo in .dwo files"
depends on DEBUG_INFO
help
Generate debug info into separate .dwo files. This significantly
reduces the build directory size for builds with DEBUG_INFO,
because it stores the information only once on disk in .dwo
files instead of multiple times in object files and executables.
In addition the debug information is also compressed.
Requires recent gcc (4.7+) and recent gdb/binutils.
Any tool that packages or reads debug information would need
to know about the .dwo files and include them.
Incompatible with older versions of ccache.
config DEBUG_INFO_DWARF4
bool "Generate dwarf4 debuginfo"
depends on DEBUG_INFO
help
Generate dwarf4 debug info. This requires recent versions
of gcc and gdb. It makes the debug information larger.
But it significantly improves the success of resolving
variables in gdb on optimized code.
config GDB_SCRIPTS
bool "Provide GDB scripts for kernel debugging"
depends on DEBUG_INFO
help
This creates the required links to GDB helper scripts in the
build directory. If you load vmlinux into gdb, the helper
scripts will be automatically imported by gdb as well, and
additional functions are available to analyze a Linux kernel
instance. See Documentation/gdb-kernel-debugging.txt for further
details.
config ENABLE_WARN_DEPRECATED
bool "Enable __deprecated logic"
default y
help
Enable the __deprecated logic in the kernel build.
Disable this to suppress the "warning: 'foo' is deprecated
(declared at kernel/power/somefile.c:1234)" messages.
config ENABLE_MUST_CHECK
bool "Enable __must_check logic"
default y
help
Enable the __must_check logic in the kernel build. Disable this to
suppress the "warning: ignoring return value of 'foo', declared with
attribute warn_unused_result" messages.
config FRAME_WARN
int "Warn for stack frames larger than (needs gcc 4.4)"
range 0 8192
default 0 if KASAN
default 1024 if !64BIT
default 2048 if 64BIT
help
Tell gcc to warn at build time for stack frames larger than this.
Setting this too low will cause a lot of warnings.
Setting it to 0 disables the warning.
Requires gcc 4.4
config STRIP_ASM_SYMS
bool "Strip assembler-generated symbols during link"
default n
help
Strip internal assembler-generated symbols during a link (symbols
that look like '.Lxxx') so they don't pollute the output of
get_wchan() and suchlike.
config READABLE_ASM
bool "Generate readable assembler code"
depends on DEBUG_KERNEL
help
Disable some compiler optimizations that tend to generate human unreadable
assembler output. This may make the kernel slightly slower, but it helps
to keep kernel developers who have to stare a lot at assembler listings
sane.
config UNUSED_SYMBOLS
bool "Enable unused/obsolete exported symbols"
default y if X86
help
Unused but exported symbols make the kernel needlessly bigger. For
that reason most of these unused exports will soon be removed. This
option is provided temporarily to provide a transition period in case
some external kernel module needs one of these symbols anyway. If you
encounter such a case in your module, consider if you are actually
using the right API. (rationale: since nobody in the kernel is using
this in a module, there is a pretty good chance it's actually the
wrong interface to use). If you really need the symbol, please send a
mail to the linux kernel mailing list mentioning the symbol and why
you really need it, and what the merge plan to the mainline kernel for
your module is.
mm/page_owner: keep track of page owners This is the page owner tracking code which is introduced so far ago. It is resident on Andrew's tree, though, nobody tried to upstream so it remain as is. Our company uses this feature actively to debug memory leak or to find a memory hogger so I decide to upstream this feature. This functionality help us to know who allocates the page. When allocating a page, we store some information about allocation in extra memory. Later, if we need to know status of all pages, we can get and analyze it from this stored information. In previous version of this feature, extra memory is statically defined in struct page, but, in this version, extra memory is allocated outside of struct page. It enables us to turn on/off this feature at boottime without considerable memory waste. Although we already have tracepoint for tracing page allocation/free, using it to analyze page owner is rather complex. We need to enlarge the trace buffer for preventing overlapping until userspace program launched. And, launched program continually dump out the trace buffer for later analysis and it would change system behaviour with more possibility rather than just keeping it in memory, so bad for debug. Moreover, we can use page_owner feature further for various purposes. For example, we can use it for fragmentation statistics implemented in this patch. And, I also plan to implement some CMA failure debugging feature using this interface. I'd like to give the credit for all developers contributed this feature, but, it's not easy because I don't know exact history. Sorry about that. Below is people who has "Signed-off-by" in the patches in Andrew's tree. Contributor: Alexander Nyberg <alexn@dsv.su.se> Mel Gorman <mgorman@suse.de> Dave Hansen <dave@linux.vnet.ibm.com> Minchan Kim <minchan@kernel.org> Michal Nazarewicz <mina86@mina86.com> Andrew Morton <akpm@linux-foundation.org> Jungsoo Son <jungsoo.son@lge.com> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Dave Hansen <dave@sr71.net> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Jungsoo Son <jungsoo.son@lge.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-13 08:56:01 +08:00
config PAGE_OWNER
bool "Track page owner"
depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
select DEBUG_FS
select STACKTRACE
select PAGE_EXTENSION
help
This keeps track of what call chain is the owner of a page, may
help to find bare alloc_page(s) leaks. Even if you include this
feature on your build, it is disabled in default. You should pass
"page_owner=on" to boot parameter in order to enable it. Eats
a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
for user-space helper.
If unsure, say N.
config DEBUG_FS
bool "Debug Filesystem"
help
debugfs is a virtual file system that kernel developers use to put
debugging files into. Enable this option to be able to read and
write to these files.
For detailed documentation on the debugfs API, see
Documentation/DocBook/filesystems.
If unsure, say N.
config HEADERS_CHECK
bool "Run 'make headers_check' when building vmlinux"
depends on !UML
help
This option will extract the user-visible kernel headers whenever
building the kernel, and will run basic sanity checks on them to
ensure that exported files do not attempt to include files which
were not exported, etc.
If you're making modifications to header files which are
relevant for userspace, say 'Y', and check the headers
exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
your build tree), to make sure they're suitable.
config DEBUG_SECTION_MISMATCH
bool "Enable full Section mismatch analysis"
help
The section mismatch analysis checks if there are illegal
references from one section to another section.
During linktime or runtime, some sections are dropped;
any use of code/data previously in these sections would
most likely result in an oops.
In the code, functions and variables are annotated with
__init,, etc. (see the full list in include/linux/init.h),
which results in the code/data being placed in specific sections.
The section mismatch analysis is always performed after a full
kernel build, and enabling this option causes the following
additional steps to occur:
- Add the option -fno-inline-functions-called-once to gcc commands.
When inlining a function annotated with __init in a non-init
function, we would lose the section information and thus
the analysis would not catch the illegal reference.
This option tells gcc to inline less (but it does result in
a larger kernel).
- Run the section mismatch analysis for each module/built-in.o file.
When we run the section mismatch analysis on vmlinux.o, we
lose valueble information about where the mismatch was
introduced.
Running the analysis for each module/built-in.o file
tells where the mismatch happens much closer to the
source. The drawback is that the same mismatch is
reported at least twice.
- Enable verbose reporting from modpost in order to help resolve
the section mismatches that are reported.
config SECTION_MISMATCH_WARN_ONLY
bool "Make section mismatch errors non-fatal"
default y
help
If you say N here, the build process will fail if there are any
section mismatch, instead of just throwing warnings.
If unsure, say Y.
#
# Select this config option from the architecture Kconfig, if it
# is preferred to always offer frame pointers as a config
# option on the architecture (regardless of KERNEL_DEBUG):
#
config ARCH_WANT_FRAME_POINTERS
bool
help
config FRAME_POINTER
bool "Compile the kernel with frame pointers"
depends on DEBUG_KERNEL && \
(CRIS || M68K || FRV || UML || \
AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
ARCH_WANT_FRAME_POINTERS
default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
help
If you say Y here the resulting kernel image will be slightly
larger and slower, but it gives very useful debugging information
in case of kernel bugs. (precise oopses/stacktraces/warnings)
config DEBUG_FORCE_WEAK_PER_CPU
bool "Force weak per-cpu definitions"
depends on DEBUG_KERNEL
help
s390 and alpha require percpu variables in modules to be
defined weak to work around addressing range issue which
puts the following two restrictions on percpu variable
definitions.
1. percpu symbols must be unique whether static or not
2. percpu variables can't be defined inside a function
To ensure that generic code follows the above rules, this
option forces all percpu variables to be defined as weak.
endmenu # "Compiler options"
config MAGIC_SYSRQ
bool "Magic SysRq key"
depends on !UML
help
If you say Y here, you will have some control over the system even
if the system crashes for example during kernel debugging (e.g., you
will be able to flush the buffer cache to disk, reboot the system
immediately or dump some status information). This is accomplished
by pressing various keys while holding SysRq (Alt+PrintScreen). It
also works on a serial console (on PC hardware at least), if you
send a BREAK and then within 5 seconds a command keypress. The
keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
unless you really know what this hack does.
config MAGIC_SYSRQ_DEFAULT_ENABLE
hex "Enable magic SysRq key functions by default"
depends on MAGIC_SYSRQ
default 0x1
help
Specifies which SysRq key functions are enabled by default.
This may be set to 1 or 0 to enable or disable them all, or
to a bitmask as described in Documentation/sysrq.txt.
config DEBUG_KERNEL
bool "Kernel debugging"
help
Say Y here if you are developing drivers or trying to debug and
identify kernel problems.
menu "Memory Debugging"
source mm/Kconfig.debug
config DEBUG_OBJECTS
bool "Debug object operations"
depends on DEBUG_KERNEL
help
If you say Y here, additional code will be inserted into the
kernel to track the life time of various objects and validate
the operations on those objects.
config DEBUG_OBJECTS_SELFTEST
bool "Debug objects selftest"
depends on DEBUG_OBJECTS
help
This enables the selftest of the object debug code.
config DEBUG_OBJECTS_FREE
bool "Debug objects in freed memory"
depends on DEBUG_OBJECTS
help
This enables checks whether a k/v free operation frees an area
which contains an object which has not been deactivated
properly. This can make kmalloc/kfree-intensive workloads
much slower.
infrastructure to debug (dynamic) objects We can see an ever repeating problem pattern with objects of any kind in the kernel: 1) freeing of active objects 2) reinitialization of active objects Both problems can be hard to debug because the crash happens at a point where we have no chance to decode the root cause anymore. One problem spot are kernel timers, where the detection of the problem often happens in interrupt context and usually causes the machine to panic. While working on a timer related bug report I had to hack specialized code into the timer subsystem to get a reasonable hint for the root cause. This debug hack was fine for temporary use, but far from a mergeable solution due to the intrusiveness into the timer code. The code further lacked the ability to detect and report the root cause instantly and keep the system operational. Keeping the system operational is important to get hold of the debug information without special debugging aids like serial consoles and special knowledge of the bug reporter. The problems described above are not restricted to timers, but timers tend to expose it usually in a full system crash. Other objects are less explosive, but the symptoms caused by such mistakes can be even harder to debug. Instead of creating specialized debugging code for the timer subsystem a generic infrastructure is created which allows developers to verify their code and provides an easy to enable debug facility for users in case of trouble. The debugobjects core code keeps track of operations on static and dynamic objects by inserting them into a hashed list and sanity checking them on object operations and provides additional checks whenever kernel memory is freed. The tracked object operations are: - initializing an object - adding an object to a subsystem list - deleting an object from a subsystem list Each operation is sanity checked before the operation is executed and the subsystem specific code can provide a fixup function which allows to prevent the damage of the operation. When the sanity check triggers a warning message and a stack trace is printed. The list of operations can be extended if the need arises. For now it's limited to the requirements of the first user (timers). The core code enqueues the objects into hash buckets. The hash index is generated from the address of the object to simplify the lookup for the check on kfree/vfree. Each bucket has it's own spinlock to avoid contention on a global lock. The debug code can be compiled in without being active. The runtime overhead is minimal and could be optimized by asm alternatives. A kernel command line option enables the debugging code. Thanks to Ingo Molnar for review, suggestions and cleanup patches. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Greg KH <greg@kroah.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 15:55:01 +08:00
config DEBUG_OBJECTS_TIMERS
bool "Debug timer objects"
depends on DEBUG_OBJECTS
help
If you say Y here, additional code will be inserted into the
timer routines to track the life time of timer objects and
validate the timer operations.
config DEBUG_OBJECTS_WORK
bool "Debug work objects"
depends on DEBUG_OBJECTS
help
If you say Y here, additional code will be inserted into the
work queue routines to track the life time of work objects and
validate the work operations.
tree/tiny rcu: Add debug RCU head objects Helps finding racy users of call_rcu(), which results in hangs because list entries are overwritten and/or skipped. Changelog since v4: - Bissectability is now OK - Now generate a WARN_ON_ONCE() for non-initialized rcu_head passed to call_rcu(). Statically initialized objects are detected with object_is_static(). - Rename rcu_head_init_on_stack to init_rcu_head_on_stack. - Remove init_rcu_head() completely. Changelog since v3: - Include comments from Lai Jiangshan This new patch version is based on the debugobjects with the newly introduced "active state" tracker. Non-initialized entries are all considered as "statically initialized". An activation fixup (triggered by call_rcu()) takes care of performing the debug object initialization without issuing any warning. Since we cannot increase the size of struct rcu_head, I don't see much room to put an identifier for statically initialized rcu_head structures. So for now, we have to live without "activation without explicit init" detection. But the main purpose of this debug option is to detect double-activations (double call_rcu() use of a rcu_head before the callback is executed), which is correctly addressed here. This also detects potential internal RCU callback corruption, which would cause the callbacks to be executed twice. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: David S. Miller <davem@davemloft.net> CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> CC: akpm@linux-foundation.org CC: mingo@elte.hu CC: laijs@cn.fujitsu.com CC: dipankar@in.ibm.com CC: josh@joshtriplett.org CC: dvhltc@us.ibm.com CC: niv@us.ibm.com CC: tglx@linutronix.de CC: peterz@infradead.org CC: rostedt@goodmis.org CC: Valdis.Kletnieks@vt.edu CC: dhowells@redhat.com CC: eric.dumazet@gmail.com CC: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2010-04-17 20:48:42 +08:00
config DEBUG_OBJECTS_RCU_HEAD
bool "Debug RCU callbacks objects"
depends on DEBUG_OBJECTS
tree/tiny rcu: Add debug RCU head objects Helps finding racy users of call_rcu(), which results in hangs because list entries are overwritten and/or skipped. Changelog since v4: - Bissectability is now OK - Now generate a WARN_ON_ONCE() for non-initialized rcu_head passed to call_rcu(). Statically initialized objects are detected with object_is_static(). - Rename rcu_head_init_on_stack to init_rcu_head_on_stack. - Remove init_rcu_head() completely. Changelog since v3: - Include comments from Lai Jiangshan This new patch version is based on the debugobjects with the newly introduced "active state" tracker. Non-initialized entries are all considered as "statically initialized". An activation fixup (triggered by call_rcu()) takes care of performing the debug object initialization without issuing any warning. Since we cannot increase the size of struct rcu_head, I don't see much room to put an identifier for statically initialized rcu_head structures. So for now, we have to live without "activation without explicit init" detection. But the main purpose of this debug option is to detect double-activations (double call_rcu() use of a rcu_head before the callback is executed), which is correctly addressed here. This also detects potential internal RCU callback corruption, which would cause the callbacks to be executed twice. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: David S. Miller <davem@davemloft.net> CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> CC: akpm@linux-foundation.org CC: mingo@elte.hu CC: laijs@cn.fujitsu.com CC: dipankar@in.ibm.com CC: josh@joshtriplett.org CC: dvhltc@us.ibm.com CC: niv@us.ibm.com CC: tglx@linutronix.de CC: peterz@infradead.org CC: rostedt@goodmis.org CC: Valdis.Kletnieks@vt.edu CC: dhowells@redhat.com CC: eric.dumazet@gmail.com CC: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2010-04-17 20:48:42 +08:00
help
Enable this to turn on debugging of RCU list heads (call_rcu() usage).
percpu_counter: add debugobj support All percpu counters are linked to a global list on initialization and removed from it on destruction. The list is walked during CPU up/down. If a percpu counter is freed without being properly destroyed, the system will oops only on the next CPU up/down making it pretty nasty to track down. This patch adds debugobj support for percpu counters so that such problems can be found easily. As percpu counters don't make sense on stack and can't be statically initialized, debugobj support is pretty simple. It's initialized and activated on counter initialization, and deactivatd and destroyed on counter destruction. With this patch applied, the bug fixed by commit 602586a83b719df0fbd94196a1359ed35aeb2df3 (shmem: put_super must percpu_counter_destroy) triggers the following warning on tmpfs unmount and the system won't oops on the next cpu up/down operation. ------------[ cut here ]------------ WARNING: at lib/debugobjects.c:259 debug_print_object+0x5c/0x70() Hardware name: Bochs ODEBUG: free active (active state 0) object type: percpu_counter Modules linked in: Pid: 3999, comm: umount Not tainted 2.6.36-rc2-work+ #5 Call Trace: [<ffffffff81083f7f>] warn_slowpath_common+0x7f/0xc0 [<ffffffff81084076>] warn_slowpath_fmt+0x46/0x50 [<ffffffff813b45cc>] debug_print_object+0x5c/0x70 [<ffffffff813b50e5>] debug_check_no_obj_freed+0x125/0x210 [<ffffffff811577d3>] kfree+0xb3/0x2f0 [<ffffffff81132edd>] shmem_put_super+0x1d/0x30 [<ffffffff81162e96>] generic_shutdown_super+0x56/0xe0 [<ffffffff81162f86>] kill_anon_super+0x16/0x60 [<ffffffff81162ff7>] kill_litter_super+0x27/0x30 [<ffffffff81163295>] deactivate_locked_super+0x45/0x60 [<ffffffff81163cfa>] deactivate_super+0x4a/0x70 [<ffffffff8117d446>] mntput_no_expire+0x86/0xe0 [<ffffffff8117df7f>] sys_umount+0x6f/0x360 [<ffffffff8103f01b>] system_call_fastpath+0x16/0x1b ---[ end trace cce2a341ba3611a7 ]--- Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Thomas Gleixner <tglxlinutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-27 05:23:05 +08:00
config DEBUG_OBJECTS_PERCPU_COUNTER
bool "Debug percpu counter objects"
depends on DEBUG_OBJECTS
help
If you say Y here, additional code will be inserted into the
percpu counter routines to track the life time of percpu counter
objects and validate the percpu counter operations.
config DEBUG_OBJECTS_ENABLE_DEFAULT
int "debug_objects bootup default value (0-1)"
range 0 1
default "1"
depends on DEBUG_OBJECTS
help
Debug objects boot parameter default value
config DEBUG_SLAB
bool "Debug slab memory allocations"
depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
help
Say Y here to have the kernel do limited verification on memory
allocation as well as poisoning memory on free to catch use of freed
memory. This can make kmalloc/kfree-intensive workloads much slower.
[PATCH] slab: implement /proc/slab_allocators Implement /proc/slab_allocators. It produces output like: idr_layer_cache: 80 idr_pre_get+0x33/0x4e buffer_head: 2555 alloc_buffer_head+0x20/0x75 mm_struct: 9 mm_alloc+0x1e/0x42 mm_struct: 20 dup_mm+0x36/0x370 vm_area_struct: 384 dup_mm+0x18f/0x370 vm_area_struct: 151 do_mmap_pgoff+0x2e0/0x7c3 vm_area_struct: 1 split_vma+0x5a/0x10e vm_area_struct: 11 do_brk+0x206/0x2e2 vm_area_struct: 2 copy_vma+0xda/0x142 vm_area_struct: 9 setup_arg_pages+0x99/0x214 fs_cache: 8 copy_fs_struct+0x21/0x133 fs_cache: 29 copy_process+0xf38/0x10e3 files_cache: 30 alloc_files+0x1b/0xcf signal_cache: 81 copy_process+0xbaa/0x10e3 sighand_cache: 77 copy_process+0xe65/0x10e3 sighand_cache: 1 de_thread+0x4d/0x5f8 anon_vma: 241 anon_vma_prepare+0xd9/0xf3 size-2048: 1 add_sect_attrs+0x5f/0x145 size-2048: 2 journal_init_revoke+0x99/0x302 size-2048: 2 journal_init_revoke+0x137/0x302 size-2048: 2 journal_init_inode+0xf9/0x1c4 Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexander Nyberg <alexn@telia.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> DESC slab-leaks3-locking-fix EDESC From: Andrew Morton <akpm@osdl.org> Update for slab-remove-cachep-spinlock.patch Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexander Nyberg <alexn@telia.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-25 19:06:39 +08:00
config DEBUG_SLAB_LEAK
bool "Memory leak debugging"
depends on DEBUG_SLAB
config SLUB_DEBUG_ON
bool "SLUB debugging on by default"
depends on SLUB && SLUB_DEBUG && !KMEMCHECK
default n
help
Boot with debugging on by default. SLUB boots by default with
the runtime debug capabilities switched off. Enabling this is
equivalent to specifying the "slub_debug" parameter on boot.
There is no support for more fine grained debug control like
possible with slub_debug=xxx. SLUB debugging may be switched
off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
"slub_debug=-".
SLUB: Support for performance statistics The statistics provided here allow the monitoring of allocator behavior but at the cost of some (minimal) loss of performance. Counters are placed in SLUB's per cpu data structure. The per cpu structure may be extended by the statistics to grow larger than one cacheline which will increase the cache footprint of SLUB. There is a compile option to enable/disable the inclusion of the runtime statistics and its off by default. The slabinfo tool is enhanced to support these statistics via two options: -D Switches the line of information displayed for a slab from size mode to activity mode. -A Sorts the slabs displayed by activity. This allows the display of the slabs most important to the performance of a certain load. -r Report option will report detailed statistics on Example (tbench load): slabinfo -AD ->Shows the most active slabs Name Objects Alloc Free %Fast skbuff_fclone_cache 33 111953835 111953835 99 99 :0000192 2666 5283688 5281047 99 99 :0001024 849 5247230 5246389 83 83 vm_area_struct 1349 119642 118355 91 22 :0004096 15 66753 66751 98 98 :0000064 2067 25297 23383 98 78 dentry 10259 28635 18464 91 45 :0000080 11004 18950 8089 98 98 :0000096 1703 12358 10784 99 98 :0000128 762 10582 9875 94 18 :0000512 184 9807 9647 95 81 :0002048 479 9669 9195 83 65 anon_vma 777 9461 9002 99 71 kmalloc-8 6492 9981 5624 99 97 :0000768 258 7174 6931 58 15 So the skbuff_fclone_cache is of highest importance for the tbench load. Pretty high load on the 192 sized slab. Look for the aliases slabinfo -a | grep 000192 :0000192 <- xfs_btree_cur filp kmalloc-192 uid_cache tw_sock_TCP request_sock_TCPv6 tw_sock_TCPv6 skbuff_head_cache xfs_ili Likely skbuff_head_cache. Looking into the statistics of the skbuff_fclone_cache is possible through slabinfo skbuff_fclone_cache ->-r option implied if cache name is mentioned .... Usual output ... Slab Perf Counter Alloc Free %Al %Fr -------------------------------------------------- Fastpath 111953360 111946981 99 99 Slowpath 1044 7423 0 0 Page Alloc 272 264 0 0 Add partial 25 325 0 0 Remove partial 86 264 0 0 RemoteObj/SlabFrozen 350 4832 0 0 Total 111954404 111954404 Flushes 49 Refill 0 Deactivate Full=325(92%) Empty=0(0%) ToHead=24(6%) ToTail=1(0%) Looks good because the fastpath is overwhelmingly taken. skbuff_head_cache: Slab Perf Counter Alloc Free %Al %Fr -------------------------------------------------- Fastpath 5297262 5259882 99 99 Slowpath 4477 39586 0 0 Page Alloc 937 824 0 0 Add partial 0 2515 0 0 Remove partial 1691 824 0 0 RemoteObj/SlabFrozen 2621 9684 0 0 Total 5301739 5299468 Deactivate Full=2620(100%) Empty=0(0%) ToHead=0(0%) ToTail=0(0%) Descriptions of the output: Total: The total number of allocation and frees that occurred for a slab Fastpath: The number of allocations/frees that used the fastpath. Slowpath: Other allocations Page Alloc: Number of calls to the page allocator as a result of slowpath processing Add Partial: Number of slabs added to the partial list through free or alloc (occurs during cpuslab flushes) Remove Partial: Number of slabs removed from the partial list as a result of allocations retrieving a partial slab or by a free freeing the last object of a slab. RemoteObj/Froz: How many times were remotely freed object encountered when a slab was about to be deactivated. Frozen: How many times was free able to skip list processing because the slab was in use as the cpuslab of another processor. Flushes: Number of times the cpuslab was flushed on request (kmem_cache_shrink, may result from races in __slab_alloc) Refill: Number of times we were able to refill the cpuslab from remotely freed objects for the same slab. Deactivate: Statistics how slabs were deactivated. Shows how they were put onto the partial list. In general fastpath is very good. Slowpath without partial list processing is also desirable. Any touching of partial list uses node specific locks which may potentially cause list lock contention. Signed-off-by: Christoph Lameter <clameter@sgi.com>
2008-02-08 09:47:41 +08:00
config SLUB_STATS
default n
bool "Enable SLUB performance statistics"
depends on SLUB && SYSFS
SLUB: Support for performance statistics The statistics provided here allow the monitoring of allocator behavior but at the cost of some (minimal) loss of performance. Counters are placed in SLUB's per cpu data structure. The per cpu structure may be extended by the statistics to grow larger than one cacheline which will increase the cache footprint of SLUB. There is a compile option to enable/disable the inclusion of the runtime statistics and its off by default. The slabinfo tool is enhanced to support these statistics via two options: -D Switches the line of information displayed for a slab from size mode to activity mode. -A Sorts the slabs displayed by activity. This allows the display of the slabs most important to the performance of a certain load. -r Report option will report detailed statistics on Example (tbench load): slabinfo -AD ->Shows the most active slabs Name Objects Alloc Free %Fast skbuff_fclone_cache 33 111953835 111953835 99 99 :0000192 2666 5283688 5281047 99 99 :0001024 849 5247230 5246389 83 83 vm_area_struct 1349 119642 118355 91 22 :0004096 15 66753 66751 98 98 :0000064 2067 25297 23383 98 78 dentry 10259 28635 18464 91 45 :0000080 11004 18950 8089 98 98 :0000096 1703 12358 10784 99 98 :0000128 762 10582 9875 94 18 :0000512 184 9807 9647 95 81 :0002048 479 9669 9195 83 65 anon_vma 777 9461 9002 99 71 kmalloc-8 6492 9981 5624 99 97 :0000768 258 7174 6931 58 15 So the skbuff_fclone_cache is of highest importance for the tbench load. Pretty high load on the 192 sized slab. Look for the aliases slabinfo -a | grep 000192 :0000192 <- xfs_btree_cur filp kmalloc-192 uid_cache tw_sock_TCP request_sock_TCPv6 tw_sock_TCPv6 skbuff_head_cache xfs_ili Likely skbuff_head_cache. Looking into the statistics of the skbuff_fclone_cache is possible through slabinfo skbuff_fclone_cache ->-r option implied if cache name is mentioned .... Usual output ... Slab Perf Counter Alloc Free %Al %Fr -------------------------------------------------- Fastpath 111953360 111946981 99 99 Slowpath 1044 7423 0 0 Page Alloc 272 264 0 0 Add partial 25 325 0 0 Remove partial 86 264 0 0 RemoteObj/SlabFrozen 350 4832 0 0 Total 111954404 111954404 Flushes 49 Refill 0 Deactivate Full=325(92%) Empty=0(0%) ToHead=24(6%) ToTail=1(0%) Looks good because the fastpath is overwhelmingly taken. skbuff_head_cache: Slab Perf Counter Alloc Free %Al %Fr -------------------------------------------------- Fastpath 5297262 5259882 99 99 Slowpath 4477 39586 0 0 Page Alloc 937 824 0 0 Add partial 0 2515 0 0 Remove partial 1691 824 0 0 RemoteObj/SlabFrozen 2621 9684 0 0 Total 5301739 5299468 Deactivate Full=2620(100%) Empty=0(0%) ToHead=0(0%) ToTail=0(0%) Descriptions of the output: Total: The total number of allocation and frees that occurred for a slab Fastpath: The number of allocations/frees that used the fastpath. Slowpath: Other allocations Page Alloc: Number of calls to the page allocator as a result of slowpath processing Add Partial: Number of slabs added to the partial list through free or alloc (occurs during cpuslab flushes) Remove Partial: Number of slabs removed from the partial list as a result of allocations retrieving a partial slab or by a free freeing the last object of a slab. RemoteObj/Froz: How many times were remotely freed object encountered when a slab was about to be deactivated. Frozen: How many times was free able to skip list processing because the slab was in use as the cpuslab of another processor. Flushes: Number of times the cpuslab was flushed on request (kmem_cache_shrink, may result from races in __slab_alloc) Refill: Number of times we were able to refill the cpuslab from remotely freed objects for the same slab. Deactivate: Statistics how slabs were deactivated. Shows how they were put onto the partial list. In general fastpath is very good. Slowpath without partial list processing is also desirable. Any touching of partial list uses node specific locks which may potentially cause list lock contention. Signed-off-by: Christoph Lameter <clameter@sgi.com>
2008-02-08 09:47:41 +08:00
help
SLUB statistics are useful to debug SLUBs allocation behavior in
order find ways to optimize the allocator. This should never be
enabled for production use since keeping statistics slows down
the allocator by a few percentage points. The slabinfo command
supports the determination of the most active slabs to figure
out which slabs are relevant to a particular load.
Try running: slabinfo -DA
config HAVE_DEBUG_KMEMLEAK
bool
config DEBUG_KMEMLEAK
bool "Kernel memory leak detector"
depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
select DEBUG_FS
select STACKTRACE if STACKTRACE_SUPPORT
select KALLSYMS
select CRC32
help
Say Y here if you want to enable the memory leak
detector. The memory allocation/freeing is traced in a way
similar to the Boehm's conservative garbage collector, the
difference being that the orphan objects are not freed but
only shown in /sys/kernel/debug/kmemleak. Enabling this
feature will introduce an overhead to memory
allocations. See Documentation/kmemleak.txt for more
details.
Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
of finding leaks due to the slab objects poisoning.
In order to access the kmemleak file, debugfs needs to be
mounted (usually at /sys/kernel/debug).
config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
int "Maximum kmemleak early log entries"
depends on DEBUG_KMEMLEAK
range 200 40000
default 400
help
Kmemleak must track all the memory allocations to avoid
reporting false positives. Since memory may be allocated or
freed before kmemleak is initialised, an early log buffer is
used to store these actions. If kmemleak reports "early log
buffer exceeded", please increase this value.
config DEBUG_KMEMLEAK_TEST
tristate "Simple test for the kernel memory leak detector"
depends on DEBUG_KMEMLEAK && m
help
This option enables a module that explicitly leaks memory.
If unsure, say N.
config DEBUG_KMEMLEAK_DEFAULT_OFF
bool "Default kmemleak to off"
depends on DEBUG_KMEMLEAK
help
Say Y here to disable kmemleak by default. It can then be enabled
on the command line via kmemleak=on.
config DEBUG_STACK_USAGE
bool "Stack utilization instrumentation"
depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
help
Enables the display of the minimum amount of free stack which each
task has ever had available in the sysrq-T and sysrq-P debug output.
This option will slow down process creation somewhat.
config DEBUG_VM
bool "Debug VM"
depends on DEBUG_KERNEL
help
Enable this to turn on extended checks in the virtual-memory system
that may impact performance.
If unsure, say N.
config DEBUG_VM_VMACACHE
bool "Debug VMA caching"
depends on DEBUG_VM
help
Enable this to turn on VMA caching debug information. Doing so
can cause significant overhead, so only enable it in non-production
environments.
If unsure, say N.
config DEBUG_VM_RB
bool "Debug VM red-black trees"
depends on DEBUG_VM
help
Enable VM red-black tree debugging information and extra validations.
If unsure, say N.
page-flags: introduce page flags policies wrt compound pages This patch adds a third argument to macros which create function definitions for page flags. This argument defines how page-flags helpers behave on compound functions. For now we define four policies: - PF_ANY: the helper function operates on the page it gets, regardless if it's non-compound, head or tail. - PF_HEAD: the helper function operates on the head page of the compound page if it gets tail page. - PF_NO_TAIL: only head and non-compond pages are acceptable for this helper function. - PF_NO_COMPOUND: only non-compound pages are acceptable for this helper function. For now we use policy PF_ANY for all helpers, which matches current behaviour. We do not enforce the policy for TESTPAGEFLAG, because we have flags checked for random pages all over the kernel. Noticeable exception to this is PageTransHuge() which triggers VM_BUG_ON() for tail page. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-16 08:51:21 +08:00
config DEBUG_VM_PGFLAGS
bool "Debug page-flags operations"
depends on DEBUG_VM
help
Enables extra validation on page flags operations.
If unsure, say N.
config DEBUG_VIRTUAL
bool "Debug VM translations"
depends on DEBUG_KERNEL && X86
help
Enable some costly sanity checks in virtual to page code. This can
catch mistakes with virt_to_page() and friends.
If unsure, say N.
config DEBUG_NOMMU_REGIONS
bool "Debug the global anon/private NOMMU mapping region tree"
depends on DEBUG_KERNEL && !MMU
help
This option causes the global tree of anonymous and private mapping
regions to be regularly checked for invalid topology.
config DEBUG_MEMORY_INIT
bool "Debug memory initialisation" if EXPERT
default !EXPERT
help
Enable this for additional checks during memory initialisation.
The sanity checks verify aspects of the VM such as the memory model
and other information provided by the architecture. Verbose
information will be printed at KERN_DEBUG loglevel depending
on the mminit_loglevel= command-line option.
If unsure, say Y
config MEMORY_NOTIFIER_ERROR_INJECT
tristate "Memory hotplug notifier error injection module"
depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
help
This option provides the ability to inject artificial errors to
memory hotplug notifier chain callbacks. It is controlled through
debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
Example: Inject memory hotplug offline error (-12 == -ENOMEM)
# cd /sys/kernel/debug/notifier-error-inject/memory
# echo -12 > actions/MEM_GOING_OFFLINE/error
# echo offline > /sys/devices/system/memory/memoryXXX/state
bash: echo: write error: Cannot allocate memory
To compile this code as a module, choose M here: the module will
be called memory-notifier-error-inject.
If unsure, say N.
config DEBUG_PER_CPU_MAPS
bool "Debug access to per_cpu maps"
depends on DEBUG_KERNEL
depends on SMP
help
Say Y to verify that the per_cpu map being accessed has
been set up. This adds a fair amount of code to kernel memory
and decreases performance.
Say N if unsure.
config DEBUG_HIGHMEM
bool "Highmem debugging"
depends on DEBUG_KERNEL && HIGHMEM
help
This option enables additional error checking for high memory
systems. Disable for production systems.
config HAVE_DEBUG_STACKOVERFLOW
bool
config DEBUG_STACKOVERFLOW
bool "Check for stack overflows"
depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
---help---
Say Y here if you want to check for overflows of kernel, IRQ
and exception stacks (if your architecture uses them). This
option will show detailed messages if free stack space drops
below a certain limit.
These kinds of bugs usually occur when call-chains in the
kernel get too deep, especially when interrupts are
involved.
Use this in cases where you see apparently random memory
corruption, especially if it appears in 'struct thread_info'
If in doubt, say "N".
source "lib/Kconfig.kmemcheck"
kasan: add kernel address sanitizer infrastructure Kernel Address sanitizer (KASan) is a dynamic memory error detector. It provides fast and comprehensive solution for finding use-after-free and out-of-bounds bugs. KASAN uses compile-time instrumentation for checking every memory access, therefore GCC > v4.9.2 required. v4.9.2 almost works, but has issues with putting symbol aliases into the wrong section, which breaks kasan instrumentation of globals. This patch only adds infrastructure for kernel address sanitizer. It's not available for use yet. The idea and some code was borrowed from [1]. Basic idea: The main idea of KASAN is to use shadow memory to record whether each byte of memory is safe to access or not, and use compiler's instrumentation to check the shadow memory on each memory access. Address sanitizer uses 1/8 of the memory addressable in kernel for shadow memory and uses direct mapping with a scale and offset to translate a memory address to its corresponding shadow address. Here is function to translate address to corresponding shadow address: unsigned long kasan_mem_to_shadow(unsigned long addr) { return (addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET; } where KASAN_SHADOW_SCALE_SHIFT = 3. So for every 8 bytes there is one corresponding byte of shadow memory. The following encoding used for each shadow byte: 0 means that all 8 bytes of the corresponding memory region are valid for access; k (1 <= k <= 7) means that the first k bytes are valid for access, and other (8 - k) bytes are not; Any negative value indicates that the entire 8-bytes are inaccessible. Different negative values used to distinguish between different kinds of inaccessible memory (redzones, freed memory) (see mm/kasan/kasan.h). To be able to detect accesses to bad memory we need a special compiler. Such compiler inserts a specific function calls (__asan_load*(addr), __asan_store*(addr)) before each memory access of size 1, 2, 4, 8 or 16. These functions check whether memory region is valid to access or not by checking corresponding shadow memory. If access is not valid an error printed. Historical background of the address sanitizer from Dmitry Vyukov: "We've developed the set of tools, AddressSanitizer (Asan), ThreadSanitizer and MemorySanitizer, for user space. We actively use them for testing inside of Google (continuous testing, fuzzing, running prod services). To date the tools have found more than 10'000 scary bugs in Chromium, Google internal codebase and various open-source projects (Firefox, OpenSSL, gcc, clang, ffmpeg, MySQL and lots of others): [2] [3] [4]. The tools are part of both gcc and clang compilers. We have not yet done massive testing under the Kernel AddressSanitizer (it's kind of chicken and egg problem, you need it to be upstream to start applying it extensively). To date it has found about 50 bugs. Bugs that we've found in upstream kernel are listed in [5]. We've also found ~20 bugs in out internal version of the kernel. Also people from Samsung and Oracle have found some. [...] As others noted, the main feature of AddressSanitizer is its performance due to inline compiler instrumentation and simple linear shadow memory. User-space Asan has ~2x slowdown on computational programs and ~2x memory consumption increase. Taking into account that kernel usually consumes only small fraction of CPU and memory when running real user-space programs, I would expect that kernel Asan will have ~10-30% slowdown and similar memory consumption increase (when we finish all tuning). I agree that Asan can well replace kmemcheck. We have plans to start working on Kernel MemorySanitizer that finds uses of unitialized memory. Asan+Msan will provide feature-parity with kmemcheck. As others noted, Asan will unlikely replace debug slab and pagealloc that can be enabled at runtime. Asan uses compiler instrumentation, so even if it is disabled, it still incurs visible overheads. Asan technology is easily portable to other architectures. Compiler instrumentation is fully portable. Runtime has some arch-dependent parts like shadow mapping and atomic operation interception. They are relatively easy to port." Comparison with other debugging features: ======================================== KMEMCHECK: - KASan can do almost everything that kmemcheck can. KASan uses compile-time instrumentation, which makes it significantly faster than kmemcheck. The only advantage of kmemcheck over KASan is detection of uninitialized memory reads. Some brief performance testing showed that kasan could be x500-x600 times faster than kmemcheck: $ netperf -l 30 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost (127.0.0.1) port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec no debug: 87380 16384 16384 30.00 41624.72 kasan inline: 87380 16384 16384 30.00 12870.54 kasan outline: 87380 16384 16384 30.00 10586.39 kmemcheck: 87380 16384 16384 30.03 20.23 - Also kmemcheck couldn't work on several CPUs. It always sets number of CPUs to 1. KASan doesn't have such limitation. DEBUG_PAGEALLOC: - KASan is slower than DEBUG_PAGEALLOC, but KASan works on sub-page granularity level, so it able to find more bugs. SLUB_DEBUG (poisoning, redzones): - SLUB_DEBUG has lower overhead than KASan. - SLUB_DEBUG in most cases are not able to detect bad reads, KASan able to detect both reads and writes. - In some cases (e.g. redzone overwritten) SLUB_DEBUG detect bugs only on allocation/freeing of object. KASan catch bugs right before it will happen, so we always know exact place of first bad read/write. [1] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel [2] https://code.google.com/p/address-sanitizer/wiki/FoundBugs [3] https://code.google.com/p/thread-sanitizer/wiki/FoundBugs [4] https://code.google.com/p/memory-sanitizer/wiki/FoundBugs [5] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel#Trophies Based on work by Andrey Konovalov. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Acked-by: Michal Marek <mmarek@suse.cz> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-14 06:39:17 +08:00
source "lib/Kconfig.kasan"
endmenu # "Memory Debugging"
config DEBUG_SHIRQ
bool "Debug shared IRQ handlers"
depends on DEBUG_KERNEL
help
Enable this to generate a spurious interrupt as soon as a shared
interrupt handler is registered, and just before one is deregistered.
Drivers ought to be able to handle interrupts coming in at those
points; some don't and need to be caught.
menu "Debug Lockups and Hangs"
lockup_detector: Combine nmi_watchdog and softlockup detector The new nmi_watchdog (which uses the perf event subsystem) is very similar in structure to the softlockup detector. Using Ingo's suggestion, I combined the two functionalities into one file: kernel/watchdog.c. Now both the nmi_watchdog (or hardlockup detector) and softlockup detector sit on top of the perf event subsystem, which is run every 60 seconds or so to see if there are any lockups. To detect hardlockups, cpus not responding to interrupts, I implemented an hrtimer that runs 5 times for every perf event overflow event. If that stops counting on a cpu, then the cpu is most likely in trouble. To detect softlockups, tasks not yielding to the scheduler, I used the previous kthread idea that now gets kicked every time the hrtimer fires. If the kthread isn't being scheduled neither is anyone else and the warning is printed to the console. I tested this on x86_64 and both the softlockup and hardlockup paths work. V2: - cleaned up the Kconfig and softlockup combination - surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI - seperated out the softlockup case from perf event subsystem - re-arranged the enabling/disabling nmi watchdog from proc space - added cpumasks for hardlockup failure cases - removed fallback to soft events if no PMU exists for hard events V3: - comment cleanups - drop support for older softlockup code - per_cpu cleanups - completely remove software clock base hardlockup detector - use per_cpu masking on hard/soft lockup detection - #ifdef cleanups - rename config option NMI_WATCHDOG to LOCKUP_DETECTOR - documentation additions V4: - documentation fixes - convert per_cpu to __get_cpu_var - powerpc compile fixes V5: - split apart warn flags for hard and soft lockups TODO: - figure out how to make an arch-agnostic clock2cycles call (if possible) to feed into perf events as a sample period [fweisbec: merged conflict patch] Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Eric Paris <eparis@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2010-05-08 05:11:44 +08:00
config LOCKUP_DETECTOR
bool "Detect Hard and Soft Lockups"
depends on DEBUG_KERNEL && !S390
help
lockup_detector: Combine nmi_watchdog and softlockup detector The new nmi_watchdog (which uses the perf event subsystem) is very similar in structure to the softlockup detector. Using Ingo's suggestion, I combined the two functionalities into one file: kernel/watchdog.c. Now both the nmi_watchdog (or hardlockup detector) and softlockup detector sit on top of the perf event subsystem, which is run every 60 seconds or so to see if there are any lockups. To detect hardlockups, cpus not responding to interrupts, I implemented an hrtimer that runs 5 times for every perf event overflow event. If that stops counting on a cpu, then the cpu is most likely in trouble. To detect softlockups, tasks not yielding to the scheduler, I used the previous kthread idea that now gets kicked every time the hrtimer fires. If the kthread isn't being scheduled neither is anyone else and the warning is printed to the console. I tested this on x86_64 and both the softlockup and hardlockup paths work. V2: - cleaned up the Kconfig and softlockup combination - surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI - seperated out the softlockup case from perf event subsystem - re-arranged the enabling/disabling nmi watchdog from proc space - added cpumasks for hardlockup failure cases - removed fallback to soft events if no PMU exists for hard events V3: - comment cleanups - drop support for older softlockup code - per_cpu cleanups - completely remove software clock base hardlockup detector - use per_cpu masking on hard/soft lockup detection - #ifdef cleanups - rename config option NMI_WATCHDOG to LOCKUP_DETECTOR - documentation additions V4: - documentation fixes - convert per_cpu to __get_cpu_var - powerpc compile fixes V5: - split apart warn flags for hard and soft lockups TODO: - figure out how to make an arch-agnostic clock2cycles call (if possible) to feed into perf events as a sample period [fweisbec: merged conflict patch] Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Eric Paris <eparis@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2010-05-08 05:11:44 +08:00
Say Y here to enable the kernel to act as a watchdog to detect
hard and soft lockups.
Softlockups are bugs that cause the kernel to loop in kernel
mode for more than 20 seconds, without giving other tasks a
lockup_detector: Combine nmi_watchdog and softlockup detector The new nmi_watchdog (which uses the perf event subsystem) is very similar in structure to the softlockup detector. Using Ingo's suggestion, I combined the two functionalities into one file: kernel/watchdog.c. Now both the nmi_watchdog (or hardlockup detector) and softlockup detector sit on top of the perf event subsystem, which is run every 60 seconds or so to see if there are any lockups. To detect hardlockups, cpus not responding to interrupts, I implemented an hrtimer that runs 5 times for every perf event overflow event. If that stops counting on a cpu, then the cpu is most likely in trouble. To detect softlockups, tasks not yielding to the scheduler, I used the previous kthread idea that now gets kicked every time the hrtimer fires. If the kthread isn't being scheduled neither is anyone else and the warning is printed to the console. I tested this on x86_64 and both the softlockup and hardlockup paths work. V2: - cleaned up the Kconfig and softlockup combination - surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI - seperated out the softlockup case from perf event subsystem - re-arranged the enabling/disabling nmi watchdog from proc space - added cpumasks for hardlockup failure cases - removed fallback to soft events if no PMU exists for hard events V3: - comment cleanups - drop support for older softlockup code - per_cpu cleanups - completely remove software clock base hardlockup detector - use per_cpu masking on hard/soft lockup detection - #ifdef cleanups - rename config option NMI_WATCHDOG to LOCKUP_DETECTOR - documentation additions V4: - documentation fixes - convert per_cpu to __get_cpu_var - powerpc compile fixes V5: - split apart warn flags for hard and soft lockups TODO: - figure out how to make an arch-agnostic clock2cycles call (if possible) to feed into perf events as a sample period [fweisbec: merged conflict patch] Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Eric Paris <eparis@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2010-05-08 05:11:44 +08:00
chance to run. The current stack trace is displayed upon
detection and the system will stay locked up.
lockup_detector: Combine nmi_watchdog and softlockup detector The new nmi_watchdog (which uses the perf event subsystem) is very similar in structure to the softlockup detector. Using Ingo's suggestion, I combined the two functionalities into one file: kernel/watchdog.c. Now both the nmi_watchdog (or hardlockup detector) and softlockup detector sit on top of the perf event subsystem, which is run every 60 seconds or so to see if there are any lockups. To detect hardlockups, cpus not responding to interrupts, I implemented an hrtimer that runs 5 times for every perf event overflow event. If that stops counting on a cpu, then the cpu is most likely in trouble. To detect softlockups, tasks not yielding to the scheduler, I used the previous kthread idea that now gets kicked every time the hrtimer fires. If the kthread isn't being scheduled neither is anyone else and the warning is printed to the console. I tested this on x86_64 and both the softlockup and hardlockup paths work. V2: - cleaned up the Kconfig and softlockup combination - surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI - seperated out the softlockup case from perf event subsystem - re-arranged the enabling/disabling nmi watchdog from proc space - added cpumasks for hardlockup failure cases - removed fallback to soft events if no PMU exists for hard events V3: - comment cleanups - drop support for older softlockup code - per_cpu cleanups - completely remove software clock base hardlockup detector - use per_cpu masking on hard/soft lockup detection - #ifdef cleanups - rename config option NMI_WATCHDOG to LOCKUP_DETECTOR - documentation additions V4: - documentation fixes - convert per_cpu to __get_cpu_var - powerpc compile fixes V5: - split apart warn flags for hard and soft lockups TODO: - figure out how to make an arch-agnostic clock2cycles call (if possible) to feed into perf events as a sample period [fweisbec: merged conflict patch] Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Eric Paris <eparis@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2010-05-08 05:11:44 +08:00
Hardlockups are bugs that cause the CPU to loop in kernel mode
for more than 10 seconds, without letting other interrupts have a
lockup_detector: Combine nmi_watchdog and softlockup detector The new nmi_watchdog (which uses the perf event subsystem) is very similar in structure to the softlockup detector. Using Ingo's suggestion, I combined the two functionalities into one file: kernel/watchdog.c. Now both the nmi_watchdog (or hardlockup detector) and softlockup detector sit on top of the perf event subsystem, which is run every 60 seconds or so to see if there are any lockups. To detect hardlockups, cpus not responding to interrupts, I implemented an hrtimer that runs 5 times for every perf event overflow event. If that stops counting on a cpu, then the cpu is most likely in trouble. To detect softlockups, tasks not yielding to the scheduler, I used the previous kthread idea that now gets kicked every time the hrtimer fires. If the kthread isn't being scheduled neither is anyone else and the warning is printed to the console. I tested this on x86_64 and both the softlockup and hardlockup paths work. V2: - cleaned up the Kconfig and softlockup combination - surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI - seperated out the softlockup case from perf event subsystem - re-arranged the enabling/disabling nmi watchdog from proc space - added cpumasks for hardlockup failure cases - removed fallback to soft events if no PMU exists for hard events V3: - comment cleanups - drop support for older softlockup code - per_cpu cleanups - completely remove software clock base hardlockup detector - use per_cpu masking on hard/soft lockup detection - #ifdef cleanups - rename config option NMI_WATCHDOG to LOCKUP_DETECTOR - documentation additions V4: - documentation fixes - convert per_cpu to __get_cpu_var - powerpc compile fixes V5: - split apart warn flags for hard and soft lockups TODO: - figure out how to make an arch-agnostic clock2cycles call (if possible) to feed into perf events as a sample period [fweisbec: merged conflict patch] Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Eric Paris <eparis@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2010-05-08 05:11:44 +08:00
chance to run. The current stack trace is displayed upon detection
and the system will stay locked up.
lockup_detector: Combine nmi_watchdog and softlockup detector The new nmi_watchdog (which uses the perf event subsystem) is very similar in structure to the softlockup detector. Using Ingo's suggestion, I combined the two functionalities into one file: kernel/watchdog.c. Now both the nmi_watchdog (or hardlockup detector) and softlockup detector sit on top of the perf event subsystem, which is run every 60 seconds or so to see if there are any lockups. To detect hardlockups, cpus not responding to interrupts, I implemented an hrtimer that runs 5 times for every perf event overflow event. If that stops counting on a cpu, then the cpu is most likely in trouble. To detect softlockups, tasks not yielding to the scheduler, I used the previous kthread idea that now gets kicked every time the hrtimer fires. If the kthread isn't being scheduled neither is anyone else and the warning is printed to the console. I tested this on x86_64 and both the softlockup and hardlockup paths work. V2: - cleaned up the Kconfig and softlockup combination - surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI - seperated out the softlockup case from perf event subsystem - re-arranged the enabling/disabling nmi watchdog from proc space - added cpumasks for hardlockup failure cases - removed fallback to soft events if no PMU exists for hard events V3: - comment cleanups - drop support for older softlockup code - per_cpu cleanups - completely remove software clock base hardlockup detector - use per_cpu masking on hard/soft lockup detection - #ifdef cleanups - rename config option NMI_WATCHDOG to LOCKUP_DETECTOR - documentation additions V4: - documentation fixes - convert per_cpu to __get_cpu_var - powerpc compile fixes V5: - split apart warn flags for hard and soft lockups TODO: - figure out how to make an arch-agnostic clock2cycles call (if possible) to feed into perf events as a sample period [fweisbec: merged conflict patch] Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Eric Paris <eparis@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2010-05-08 05:11:44 +08:00
The overhead should be minimal. A periodic hrtimer runs to
generate interrupts and kick the watchdog task every 4 seconds.
An NMI is generated every 10 seconds or so to check for hardlockups.
The frequency of hrtimer and NMI events and the soft and hard lockup
thresholds can be controlled through the sysctl watchdog_thresh.
config HARDLOCKUP_DETECTOR
def_bool y
depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
config BOOTPARAM_HARDLOCKUP_PANIC
bool "Panic (Reboot) On Hard Lockups"
depends on HARDLOCKUP_DETECTOR
help
Say Y here to enable the kernel to panic on "hard lockups",
which are bugs that cause the kernel to loop in kernel
mode with interrupts disabled for more than 10 seconds (configurable
using the watchdog_thresh sysctl).
Say N if unsure.
config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
int
depends on HARDLOCKUP_DETECTOR
range 0 1
default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
default 1 if BOOTPARAM_HARDLOCKUP_PANIC
config BOOTPARAM_SOFTLOCKUP_PANIC
bool "Panic (Reboot) On Soft Lockups"
depends on LOCKUP_DETECTOR
help
Say Y here to enable the kernel to panic on "soft lockups",
which are bugs that cause the kernel to loop in kernel
mode for more than 20 seconds (configurable using the watchdog_thresh
sysctl), without giving other tasks a chance to run.
The panic can be used in combination with panic_timeout,
to cause the system to reboot automatically after a
lockup has been detected. This feature is useful for
high-availability systems that have uptime guarantees and
where a lockup must be resolved ASAP.
Say N if unsure.
config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
int
depends on LOCKUP_DETECTOR
range 0 1
default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
config DETECT_HUNG_TASK
bool "Detect Hung Tasks"
depends on DEBUG_KERNEL
default LOCKUP_DETECTOR
help
Say Y here to enable the kernel to detect "hung tasks",
which are bugs that cause the task to be stuck in
uninterruptible "D" state indefinitiley.
When a hung task is detected, the kernel will print the
current stack trace (which you should report), but the
task will stay in uninterruptible state. If lockdep is
enabled then all held locks will also be reported. This
feature has negligible overhead.
[PATCH] slab: implement /proc/slab_allocators Implement /proc/slab_allocators. It produces output like: idr_layer_cache: 80 idr_pre_get+0x33/0x4e buffer_head: 2555 alloc_buffer_head+0x20/0x75 mm_struct: 9 mm_alloc+0x1e/0x42 mm_struct: 20 dup_mm+0x36/0x370 vm_area_struct: 384 dup_mm+0x18f/0x370 vm_area_struct: 151 do_mmap_pgoff+0x2e0/0x7c3 vm_area_struct: 1 split_vma+0x5a/0x10e vm_area_struct: 11 do_brk+0x206/0x2e2 vm_area_struct: 2 copy_vma+0xda/0x142 vm_area_struct: 9 setup_arg_pages+0x99/0x214 fs_cache: 8 copy_fs_struct+0x21/0x133 fs_cache: 29 copy_process+0xf38/0x10e3 files_cache: 30 alloc_files+0x1b/0xcf signal_cache: 81 copy_process+0xbaa/0x10e3 sighand_cache: 77 copy_process+0xe65/0x10e3 sighand_cache: 1 de_thread+0x4d/0x5f8 anon_vma: 241 anon_vma_prepare+0xd9/0xf3 size-2048: 1 add_sect_attrs+0x5f/0x145 size-2048: 2 journal_init_revoke+0x99/0x302 size-2048: 2 journal_init_revoke+0x137/0x302 size-2048: 2 journal_init_inode+0xf9/0x1c4 Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexander Nyberg <alexn@telia.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> DESC slab-leaks3-locking-fix EDESC From: Andrew Morton <akpm@osdl.org> Update for slab-remove-cachep-spinlock.patch Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexander Nyberg <alexn@telia.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-25 19:06:39 +08:00
config DEFAULT_HUNG_TASK_TIMEOUT
int "Default timeout for hung task detection (in seconds)"
depends on DETECT_HUNG_TASK
default 120
help
This option controls the default timeout (in seconds) used
to determine when a task has become non-responsive and should
be considered hung.
It can be adjusted at runtime via the kernel.hung_task_timeout_secs
sysctl or by writing a value to
/proc/sys/kernel/hung_task_timeout_secs.
SLUB: Support for performance statistics The statistics provided here allow the monitoring of allocator behavior but at the cost of some (minimal) loss of performance. Counters are placed in SLUB's per cpu data structure. The per cpu structure may be extended by the statistics to grow larger than one cacheline which will increase the cache footprint of SLUB. There is a compile option to enable/disable the inclusion of the runtime statistics and its off by default. The slabinfo tool is enhanced to support these statistics via two options: -D Switches the line of information displayed for a slab from size mode to activity mode. -A Sorts the slabs displayed by activity. This allows the display of the slabs most important to the performance of a certain load. -r Report option will report detailed statistics on Example (tbench load): slabinfo -AD ->Shows the most active slabs Name Objects Alloc Free %Fast skbuff_fclone_cache 33 111953835 111953835 99 99 :0000192 2666 5283688 5281047 99 99 :0001024 849 5247230 5246389 83 83 vm_area_struct 1349 119642 118355 91 22 :0004096 15 66753 66751 98 98 :0000064 2067 25297 23383 98 78 dentry 10259 28635 18464 91 45 :0000080 11004 18950 8089 98 98 :0000096 1703 12358 10784 99 98 :0000128 762 10582 9875 94 18 :0000512 184 9807 9647 95 81 :0002048 479 9669 9195 83 65 anon_vma 777 9461 9002 99 71 kmalloc-8 6492 9981 5624 99 97 :0000768 258 7174 6931 58 15 So the skbuff_fclone_cache is of highest importance for the tbench load. Pretty high load on the 192 sized slab. Look for the aliases slabinfo -a | grep 000192 :0000192 <- xfs_btree_cur filp kmalloc-192 uid_cache tw_sock_TCP request_sock_TCPv6 tw_sock_TCPv6 skbuff_head_cache xfs_ili Likely skbuff_head_cache. Looking into the statistics of the skbuff_fclone_cache is possible through slabinfo skbuff_fclone_cache ->-r option implied if cache name is mentioned .... Usual output ... Slab Perf Counter Alloc Free %Al %Fr -------------------------------------------------- Fastpath 111953360 111946981 99 99 Slowpath 1044 7423 0 0 Page Alloc 272 264 0 0 Add partial 25 325 0 0 Remove partial 86 264 0 0 RemoteObj/SlabFrozen 350 4832 0 0 Total 111954404 111954404 Flushes 49 Refill 0 Deactivate Full=325(92%) Empty=0(0%) ToHead=24(6%) ToTail=1(0%) Looks good because the fastpath is overwhelmingly taken. skbuff_head_cache: Slab Perf Counter Alloc Free %Al %Fr -------------------------------------------------- Fastpath 5297262 5259882 99 99 Slowpath 4477 39586 0 0 Page Alloc 937 824 0 0 Add partial 0 2515 0 0 Remove partial 1691 824 0 0 RemoteObj/SlabFrozen 2621 9684 0 0 Total 5301739 5299468 Deactivate Full=2620(100%) Empty=0(0%) ToHead=0(0%) ToTail=0(0%) Descriptions of the output: Total: The total number of allocation and frees that occurred for a slab Fastpath: The number of allocations/frees that used the fastpath. Slowpath: Other allocations Page Alloc: Number of calls to the page allocator as a result of slowpath processing Add Partial: Number of slabs added to the partial list through free or alloc (occurs during cpuslab flushes) Remove Partial: Number of slabs removed from the partial list as a result of allocations retrieving a partial slab or by a free freeing the last object of a slab. RemoteObj/Froz: How many times were remotely freed object encountered when a slab was about to be deactivated. Frozen: How many times was free able to skip list processing because the slab was in use as the cpuslab of another processor. Flushes: Number of times the cpuslab was flushed on request (kmem_cache_shrink, may result from races in __slab_alloc) Refill: Number of times we were able to refill the cpuslab from remotely freed objects for the same slab. Deactivate: Statistics how slabs were deactivated. Shows how they were put onto the partial list. In general fastpath is very good. Slowpath without partial list processing is also desirable. Any touching of partial list uses node specific locks which may potentially cause list lock contention. Signed-off-by: Christoph Lameter <clameter@sgi.com>
2008-02-08 09:47:41 +08:00
A timeout of 0 disables the check. The default is two minutes.
Keeping the default should be fine in most cases.
config BOOTPARAM_HUNG_TASK_PANIC
bool "Panic (Reboot) On Hung Tasks"
depends on DETECT_HUNG_TASK
help
Say Y here to enable the kernel to panic on "hung tasks",
which are bugs that cause the kernel to leave a task stuck
in uninterruptible "D" state.
The panic can be used in combination with panic_timeout,
to cause the system to reboot automatically after a
hung task has been detected. This feature is useful for
high-availability systems that have uptime guarantees and
where a hung tasks must be resolved ASAP.
Say N if unsure.
config BOOTPARAM_HUNG_TASK_PANIC_VALUE
int
depends on DETECT_HUNG_TASK
range 0 1
default 0 if !BOOTPARAM_HUNG_TASK_PANIC
default 1 if BOOTPARAM_HUNG_TASK_PANIC
workqueue: implement lockup detector Workqueue stalls can happen from a variety of usage bugs such as missing WQ_MEM_RECLAIM flag or concurrency managed work item indefinitely staying RUNNING. These stalls can be extremely difficult to hunt down because the usual warning mechanisms can't detect workqueue stalls and the internal state is pretty opaque. To alleviate the situation, this patch implements workqueue lockup detector. It periodically monitors all worker_pools periodically and, if any pool failed to make forward progress longer than the threshold duration, triggers warning and dumps workqueue state as follows. BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 31s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=17/256 pending: monkey_wrench_fn, e1000_watchdog, cache_reap, vmstat_shepherd, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, cgroup_release_agent workqueue events_power_efficient: flags=0x80 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256 pending: check_lifetime, neigh_periodic_work workqueue cgroup_pidlist_destroy: flags=0x0 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1 pending: cgroup_pidlist_destroy_work_fn ... The detection mechanism is controller through kernel parameter workqueue.watchdog_thresh and can be updated at runtime through the sysfs module parameter file. v2: Decoupled from softlockup control knobs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Don Zickus <dzickus@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2015-12-09 00:28:04 +08:00
config WQ_WATCHDOG
bool "Detect Workqueue Stalls"
depends on DEBUG_KERNEL
help
Say Y here to enable stall detection on workqueues. If a
worker pool doesn't make forward progress on a pending work
item for over a given amount of time, 30s by default, a
warning message is printed along with dump of workqueue
state. This can be configured through kernel parameter
"workqueue.watchdog_thresh" and its sysfs counterpart.
endmenu # "Debug lockups and hangs"
config PANIC_ON_OOPS
bool "Panic on Oops"
help
Say Y here to enable the kernel to panic when it oopses. This
has the same effect as setting oops=panic on the kernel command
line.
This feature is useful to ensure that the kernel does not do
anything erroneous after an oops which could result in data
corruption or other issues.
Say N if unsure.
config PANIC_ON_OOPS_VALUE
int
range 0 1
default 0 if !PANIC_ON_OOPS
default 1 if PANIC_ON_OOPS
config PANIC_TIMEOUT
int "panic timeout"
default 0
help
Set the timeout value (in seconds) until a reboot occurs when the
the kernel panics. If n = 0, then we wait forever. A timeout
value n > 0 will wait n seconds before rebooting, while a timeout
value n < 0 will reboot immediately.
config SCHED_DEBUG
bool "Collect scheduler debugging info"
depends on DEBUG_KERNEL && PROC_FS
default y
help
If you say Y here, the /proc/sched_debug file will be provided
that can help debug the scheduler. The runtime overhead of this
option is minimal.
config SCHED_INFO
bool
default n
config SCHEDSTATS
bool "Collect scheduler statistics"
depends on DEBUG_KERNEL && PROC_FS
select SCHED_INFO
help
If you say Y here, additional code will be inserted into the
scheduler and related routines to collect statistics about
scheduler behavior and provide them in /proc/schedstat. These
stats may be useful for both tuning and debugging the scheduler
If you aren't debugging the scheduler or trying to tune a specific
application, you can say N to avoid the very slight overhead
this adds.
sched: Add default-disabled option to BUG() when stack end location is overwritten Currently in the event of a stack overrun a call to schedule() does not check for this type of corruption. This corruption is often silent and can go unnoticed. However once the corrupted region is examined at a later stage, the outcome is undefined and often results in a sporadic page fault which cannot be handled. This patch checks for a stack overrun and takes appropriate action since the damage is already done, there is no point in continuing. Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: aneesh.kumar@linux.vnet.ibm.com Cc: dzickus@redhat.com Cc: bmr@redhat.com Cc: jcastillo@redhat.com Cc: oleg@redhat.com Cc: riel@redhat.com Cc: prarit@redhat.com Cc: jgh@redhat.com Cc: minchan@kernel.org Cc: mpe@ellerman.id.au Cc: tglx@linutronix.de Cc: rostedt@goodmis.org Cc: hannes@cmpxchg.org Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: David S. Miller <davem@davemloft.net> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Lubomir Rintel <lkundrak@v3.sk> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1410527779-8133-4-git-send-email-atomlin@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-12 21:16:19 +08:00
config SCHED_STACK_END_CHECK
bool "Detect stack corruption on calls to schedule()"
depends on DEBUG_KERNEL
default n
help
This option checks for a stack overrun on calls to schedule().
If the stack end location is found to be over written always panic as
the content of the corrupted region can no longer be trusted.
This is to ensure no erroneous behaviour occurs which could result in
data corruption or a sporadic crash at a later stage once the region
is examined. The runtime overhead introduced is minimal.
config DEBUG_TIMEKEEPING
bool "Enable extra timekeeping sanity checking"
help
This option will enable additional timekeeping sanity checks
which may be helpful when diagnosing issues where timekeeping
problems are suspected.
This may include checks in the timekeeping hotpaths, so this
option may have a (very small) performance impact to some
workloads.
If unsure, say N.
config TIMER_STATS
bool "Collect kernel timers statistics"
depends on DEBUG_KERNEL && PROC_FS
help
If you say Y here, additional code will be inserted into the
timer routines to collect statistics about kernel timers being
reprogrammed. The statistics can be read from /proc/timer_stats.
The statistics collection is started by writing 1 to /proc/timer_stats,
writing 0 stops it. This feature is useful to collect information
about timer usage patterns in kernel and userspace. This feature
is lightweight if enabled in the kernel config but not activated
(it defaults to deactivated on bootup and will only be activated
if some application like powertop activates it explicitly).
config DEBUG_PREEMPT
bool "Debug preemptible kernel"
depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
default y
help
If you say Y here then the kernel will use a debug variant of the
commonly used smp_processor_id() function and will print warnings
if kernel code uses it in a preemption-unsafe way. Also, the kernel
will detect preemption count underflows.
menu "Lock Debugging (spinlocks, mutexes, etc...)"
config DEBUG_RT_MUTEXES
bool "RT Mutex debugging, deadlock detection"
depends on DEBUG_KERNEL && RT_MUTEXES
help
This allows rt mutex semantics violations and rt mutex related
deadlocks (lockups) to be detected and reported automatically.
config DEBUG_SPINLOCK
bool "Spinlock and rw-lock debugging: basic checks"
depends on DEBUG_KERNEL
select UNINLINE_SPIN_UNLOCK
help
Say Y here and build SMP to catch missing spinlock initialization
and certain other kinds of spinlock errors commonly made. This is
best used in conjunction with the NMI watchdog so that spinlock
deadlocks are also debuggable.
config DEBUG_MUTEXES
bool "Mutex debugging: basic checks"
depends on DEBUG_KERNEL
help
This feature allows mutex semantics violations to be detected and
reported.
mutex: Add w/w mutex slowpath debugging Injects EDEADLK conditions at pseudo-random interval, with exponential backoff up to UINT_MAX (to ensure that every lock operation still completes in a reasonable time). This way we can test the wound slowpath even for ww mutex users where contention is never expected, and the ww deadlock avoidance algorithm is only needed for correctness against malicious userspace. An example would be protecting kernel modesetting properties, which thanks to single-threaded X isn't really expected to contend, ever. I've looked into using the CONFIG_FAULT_INJECTION infrastructure, but decided against it for two reasons: - EDEADLK handling is mandatory for ww mutex users and should never affect the outcome of a syscall. This is in contrast to -ENOMEM injection. So fine configurability isn't required. - The fault injection framework only allows to set a simple probability for failure. Now the probability that a ww mutex acquire stage with N locks will never complete (due to too many injected EDEADLK backoffs) is zero. But the expected number of ww_mutex_lock operations for the completely uncontended case would be O(exp(N)). The per-acuiqire ctx exponential backoff solution choosen here only results in O(log N) overhead due to injection and so O(log N * N) lock operations. This way we can fail with high probability (and so have good test coverage even for fancy backoff and lock acquisition paths) without running into patalogical cases. Note that EDEADLK will only ever be injected when we managed to acquire the lock. This prevents any behaviour changes for users which rely on the EALREADY semantics. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20130620113117.4001.21681.stgit@patser Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-06-20 19:31:17 +08:00
config DEBUG_WW_MUTEX_SLOWPATH
bool "Wait/wound mutex debugging: Slowpath testing"
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
select DEBUG_LOCK_ALLOC
select DEBUG_SPINLOCK
select DEBUG_MUTEXES
help
This feature enables slowpath testing for w/w mutex users by
injecting additional -EDEADLK wound/backoff cases. Together with
the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
will test all possible w/w mutex interface abuse with the
exception of simply not acquiring all the required locks.
Note that this feature can introduce significant overhead, so
it really should not be enabled in a production or distro kernel,
even a debug kernel. If you are a driver writer, enable it. If
you are a distro, do not.
mutex: Add w/w mutex slowpath debugging Injects EDEADLK conditions at pseudo-random interval, with exponential backoff up to UINT_MAX (to ensure that every lock operation still completes in a reasonable time). This way we can test the wound slowpath even for ww mutex users where contention is never expected, and the ww deadlock avoidance algorithm is only needed for correctness against malicious userspace. An example would be protecting kernel modesetting properties, which thanks to single-threaded X isn't really expected to contend, ever. I've looked into using the CONFIG_FAULT_INJECTION infrastructure, but decided against it for two reasons: - EDEADLK handling is mandatory for ww mutex users and should never affect the outcome of a syscall. This is in contrast to -ENOMEM injection. So fine configurability isn't required. - The fault injection framework only allows to set a simple probability for failure. Now the probability that a ww mutex acquire stage with N locks will never complete (due to too many injected EDEADLK backoffs) is zero. But the expected number of ww_mutex_lock operations for the completely uncontended case would be O(exp(N)). The per-acuiqire ctx exponential backoff solution choosen here only results in O(log N) overhead due to injection and so O(log N * N) lock operations. This way we can fail with high probability (and so have good test coverage even for fancy backoff and lock acquisition paths) without running into patalogical cases. Note that EDEADLK will only ever be injected when we managed to acquire the lock. This prevents any behaviour changes for users which rely on the EALREADY semantics. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20130620113117.4001.21681.stgit@patser Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-06-20 19:31:17 +08:00
config DEBUG_LOCK_ALLOC
bool "Lock debugging: detect incorrect freeing of live locks"
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
select DEBUG_SPINLOCK
select DEBUG_MUTEXES
select LOCKDEP
help
This feature will check whether any held lock (spinlock, rwlock,
mutex or rwsem) is incorrectly freed by the kernel, via any of the
memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
vfree(), etc.), whether a live lock is incorrectly reinitialized via
spin_lock_init()/mutex_init()/etc., or whether there is any lock
held during task exit.
config PROVE_LOCKING
bool "Lock debugging: prove locking correctness"
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
select LOCKDEP
select DEBUG_SPINLOCK
select DEBUG_MUTEXES
select DEBUG_LOCK_ALLOC
select TRACE_IRQFLAGS
default n
help
This feature enables the kernel to prove that all locking
that occurs in the kernel runtime is mathematically
correct: that under no circumstance could an arbitrary (and
not yet triggered) combination of observed locking
sequences (on an arbitrary number of CPUs, running an
arbitrary number of tasks and interrupt contexts) cause a
deadlock.
In short, this feature enables the kernel to report locking
related deadlocks before they actually occur.
The proof does not depend on how hard and complex a
deadlock scenario would be to trigger: how many
participant CPUs, tasks and irq-contexts would be needed
for it to trigger. The proof also does not depend on
timing: if a race and a resulting deadlock is possible
theoretically (no matter how unlikely the race scenario
is), it will be proven so and will immediately be
reported by the kernel (once the event is observed that
makes the deadlock theoretically possible).
If a deadlock is impossible (i.e. the locking rules, as
observed by the kernel, are mathematically correct), the
kernel reports nothing.
NOTE: this feature can also be enabled for rwlocks, mutexes
and rwsems - in which case all dependencies between these
different locking variants are observed and mapped too, and
the proof of observed correctness is also maintained for an
arbitrary combination of these separate locking variants.
locking/Documentation: Move locking related docs into Documentation/locking/ Specifically: Documentation/locking/lockdep-design.txt Documentation/locking/lockstat.txt Documentation/locking/mutex-design.txt Documentation/locking/rt-mutex-design.txt Documentation/locking/rt-mutex.txt Documentation/locking/spinlocks.txt Documentation/locking/ww-mutex-design.txt Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: jason.low2@hp.com Cc: aswin@hp.com Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Mason <clm@fb.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: David Airlie <airlied@linux.ie> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: David S. Miller <davem@davemloft.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Jason Low <jason.low2@hp.com> Cc: Josef Bacik <jbacik@fusionio.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Lubomir Rintel <lkundrak@v3.sk> Cc: Masanari Iida <standby24x7@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: fengguang.wu@intel.com Link: http://lkml.kernel.org/r/1406752916-3341-6-git-send-email-davidlohr@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-07-31 04:41:55 +08:00
For more details, see Documentation/locking/lockdep-design.txt.
config LOCKDEP
bool
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
select STACKTRACE
select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
select KALLSYMS
select KALLSYMS_ALL
lockstat: core infrastructure Introduce the core lock statistics code. Lock statistics provides lock wait-time and hold-time (as well as the count of corresponding contention and acquisitions events). Also, the first few call-sites that encounter contention are tracked. Lock wait-time is the time spent waiting on the lock. This provides insight into the locking scheme, that is, a heavily contended lock is indicative of a too coarse locking scheme. Lock hold-time is the duration the lock was held, this provides a reference for the wait-time numbers, so they can be put into perspective. 1) lock 2) ... do stuff .. unlock 3) The time between 1 and 2 is the wait-time. The time between 2 and 3 is the hold-time. The lockdep held-lock tracking code is reused, because it already collects locks into meaningful groups (classes), and because it is an existing infrastructure for lock instrumentation. Currently lockdep tracks lock acquisition with two hooks: lock() lock_acquire() _lock() ... code protected by lock ... unlock() lock_release() _unlock() We need to extend this with two more hooks, in order to measure contention. lock_contended() - used to measure contention events lock_acquired() - completion of the contention These are then placed the following way: lock() lock_acquire() if (!_try_lock()) lock_contended() _lock() lock_acquired() ... do locked stuff ... unlock() lock_release() _unlock() (Note: the try_lock() 'trick' is used to avoid instrumenting all platform dependent lock primitive implementations.) It is also possible to toggle the two lockdep features at runtime using: /proc/sys/kernel/prove_locking /proc/sys/kernel/lock_stat (esp. turning off the O(n^2) prove_locking functionaliy can help) [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: nuke unneeded ifdefs] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 16:48:56 +08:00
config LOCK_STAT
bool "Lock usage statistics"
lockstat: core infrastructure Introduce the core lock statistics code. Lock statistics provides lock wait-time and hold-time (as well as the count of corresponding contention and acquisitions events). Also, the first few call-sites that encounter contention are tracked. Lock wait-time is the time spent waiting on the lock. This provides insight into the locking scheme, that is, a heavily contended lock is indicative of a too coarse locking scheme. Lock hold-time is the duration the lock was held, this provides a reference for the wait-time numbers, so they can be put into perspective. 1) lock 2) ... do stuff .. unlock 3) The time between 1 and 2 is the wait-time. The time between 2 and 3 is the hold-time. The lockdep held-lock tracking code is reused, because it already collects locks into meaningful groups (classes), and because it is an existing infrastructure for lock instrumentation. Currently lockdep tracks lock acquisition with two hooks: lock() lock_acquire() _lock() ... code protected by lock ... unlock() lock_release() _unlock() We need to extend this with two more hooks, in order to measure contention. lock_contended() - used to measure contention events lock_acquired() - completion of the contention These are then placed the following way: lock() lock_acquire() if (!_try_lock()) lock_contended() _lock() lock_acquired() ... do locked stuff ... unlock() lock_release() _unlock() (Note: the try_lock() 'trick' is used to avoid instrumenting all platform dependent lock primitive implementations.) It is also possible to toggle the two lockdep features at runtime using: /proc/sys/kernel/prove_locking /proc/sys/kernel/lock_stat (esp. turning off the O(n^2) prove_locking functionaliy can help) [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: nuke unneeded ifdefs] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 16:48:56 +08:00
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
select LOCKDEP
select DEBUG_SPINLOCK
select DEBUG_MUTEXES
select DEBUG_LOCK_ALLOC
default n
help
This feature enables tracking lock contention points
locking/Documentation: Move locking related docs into Documentation/locking/ Specifically: Documentation/locking/lockdep-design.txt Documentation/locking/lockstat.txt Documentation/locking/mutex-design.txt Documentation/locking/rt-mutex-design.txt Documentation/locking/rt-mutex.txt Documentation/locking/spinlocks.txt Documentation/locking/ww-mutex-design.txt Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: jason.low2@hp.com Cc: aswin@hp.com Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Mason <clm@fb.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: David Airlie <airlied@linux.ie> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: David S. Miller <davem@davemloft.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Jason Low <jason.low2@hp.com> Cc: Josef Bacik <jbacik@fusionio.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Lubomir Rintel <lkundrak@v3.sk> Cc: Masanari Iida <standby24x7@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: fengguang.wu@intel.com Link: http://lkml.kernel.org/r/1406752916-3341-6-git-send-email-davidlohr@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-07-31 04:41:55 +08:00
For more details, see Documentation/locking/lockstat.txt
This also enables lock events required by "perf lock",
subcommand of perf.
If you want to use "perf lock", you also need to turn on
CONFIG_EVENT_TRACING.
CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
(CONFIG_LOCKDEP defines "acquire" and "release" events.)
config DEBUG_LOCKDEP
bool "Lock dependency engine debugging"
depends on DEBUG_KERNEL && LOCKDEP
help
If you say Y here, the lock dependency engine will do
additional runtime checks to debug itself, at the price
of more runtime overhead.
config DEBUG_ATOMIC_SLEEP
bool "Sleep inside atomic section checking"
select PREEMPT_COUNT
depends on DEBUG_KERNEL
help
If you say Y here, various routines which may sleep will become very
noisy if they are called inside atomic sections: when a spinlock is
held, inside an rcu read side critical section, inside preempt disabled
sections, inside an interrupt, etc...
[PATCH] lockdep: locking API self tests Introduce DEBUG_LOCKING_API_SELFTESTS, which uses the generic lock debugging code's silent-failure feature to run a matrix of testcases. There are 210 testcases currently: +----------------------- | Locking API testsuite: +------------------------------+------+------+------+------+------+------+ | spin |wlock |rlock |mutex | wsem | rsem | -------------------------------+------+------+------+------+------+------+ A-A deadlock: ok | ok | ok | ok | ok | ok | A-B-B-A deadlock: ok | ok | ok | ok | ok | ok | A-B-B-C-C-A deadlock: ok | ok | ok | ok | ok | ok | A-B-C-A-B-C deadlock: ok | ok | ok | ok | ok | ok | A-B-B-C-C-D-D-A deadlock: ok | ok | ok | ok | ok | ok | A-B-C-D-B-D-D-A deadlock: ok | ok | ok | ok | ok | ok | A-B-C-D-B-C-D-A deadlock: ok | ok | ok | ok | ok | ok | double unlock: ok | ok | ok | ok | ok | ok | bad unlock order: ok | ok | ok | ok | ok | ok | --------------------------------------+------+------+------+------+------+ recursive read-lock: | ok | | ok | --------------------------------------+------+------+------+------+------+ non-nested unlock: ok | ok | ok | ok | --------------------------------------+------+------+------+ hard-irqs-on + irq-safe-A/12: ok | ok | ok | soft-irqs-on + irq-safe-A/12: ok | ok | ok | hard-irqs-on + irq-safe-A/21: ok | ok | ok | soft-irqs-on + irq-safe-A/21: ok | ok | ok | sirq-safe-A => hirqs-on/12: ok | ok | ok | sirq-safe-A => hirqs-on/21: ok | ok | ok | hard-safe-A + irqs-on/12: ok | ok | ok | soft-safe-A + irqs-on/12: ok | ok | ok | hard-safe-A + irqs-on/21: ok | ok | ok | soft-safe-A + irqs-on/21: ok | ok | ok | hard-safe-A + unsafe-B #1/123: ok | ok | ok | soft-safe-A + unsafe-B #1/123: ok | ok | ok | hard-safe-A + unsafe-B #1/132: ok | ok | ok | soft-safe-A + unsafe-B #1/132: ok | ok | ok | hard-safe-A + unsafe-B #1/213: ok | ok | ok | soft-safe-A + unsafe-B #1/213: ok | ok | ok | hard-safe-A + unsafe-B #1/231: ok | ok | ok | soft-safe-A + unsafe-B #1/231: ok | ok | ok | hard-safe-A + unsafe-B #1/312: ok | ok | ok | soft-safe-A + unsafe-B #1/312: ok | ok | ok | hard-safe-A + unsafe-B #1/321: ok | ok | ok | soft-safe-A + unsafe-B #1/321: ok | ok | ok | hard-safe-A + unsafe-B #2/123: ok | ok | ok | soft-safe-A + unsafe-B #2/123: ok | ok | ok | hard-safe-A + unsafe-B #2/132: ok | ok | ok | soft-safe-A + unsafe-B #2/132: ok | ok | ok | hard-safe-A + unsafe-B #2/213: ok | ok | ok | soft-safe-A + unsafe-B #2/213: ok | ok | ok | hard-safe-A + unsafe-B #2/231: ok | ok | ok | soft-safe-A + unsafe-B #2/231: ok | ok | ok | hard-safe-A + unsafe-B #2/312: ok | ok | ok | soft-safe-A + unsafe-B #2/312: ok | ok | ok | hard-safe-A + unsafe-B #2/321: ok | ok | ok | soft-safe-A + unsafe-B #2/321: ok | ok | ok | hard-irq lock-inversion/123: ok | ok | ok | soft-irq lock-inversion/123: ok | ok | ok | hard-irq lock-inversion/132: ok | ok | ok | soft-irq lock-inversion/132: ok | ok | ok | hard-irq lock-inversion/213: ok | ok | ok | soft-irq lock-inversion/213: ok | ok | ok | hard-irq lock-inversion/231: ok | ok | ok | soft-irq lock-inversion/231: ok | ok | ok | hard-irq lock-inversion/312: ok | ok | ok | soft-irq lock-inversion/312: ok | ok | ok | hard-irq lock-inversion/321: ok | ok | ok | soft-irq lock-inversion/321: ok | ok | ok | hard-irq read-recursion/123: ok | soft-irq read-recursion/123: ok | hard-irq read-recursion/132: ok | soft-irq read-recursion/132: ok | hard-irq read-recursion/213: ok | soft-irq read-recursion/213: ok | hard-irq read-recursion/231: ok | soft-irq read-recursion/231: ok | hard-irq read-recursion/312: ok | soft-irq read-recursion/312: ok | hard-irq read-recursion/321: ok | soft-irq read-recursion/321: ok | --------------------------------+-----+---------------- Good, all 210 testcases passed! | --------------------------------+ Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03 15:24:48 +08:00
config DEBUG_LOCKING_API_SELFTESTS
bool "Locking API boot-time self-tests"
depends on DEBUG_KERNEL
help
Say Y here if you want the kernel to run a short self-test during
bootup. The self-test checks whether common types of locking bugs
are detected by debugging mechanisms or not. (if you disable
lock debugging then those bugs wont be detected of course.)
The following locking APIs are covered: spinlocks, rwlocks,
mutexes and rwsems.
config LOCK_TORTURE_TEST
tristate "torture tests for locking"
depends on DEBUG_KERNEL
select TORTURE_TEST
default n
help
This option provides a kernel module that runs torture tests
on kernel locking primitives. The kernel module may be built
after the fact on the running kernel to be tested, if desired.
Say Y here if you want kernel locking-primitive torture tests
to be built into the kernel.
Say M if you want these torture tests to build as a module.
Say N if you are unsure.
endmenu # lock debugging
config TRACE_IRQFLAGS
bool
help
Enables hooks to interrupt enabling and disabling for
either tracing or lock debugging.
config STACKTRACE
bool "Stack backtrace support"
depends on STACKTRACE_SUPPORT
help
This option causes the kernel to create a /proc/pid/stack for
every process, showing its current stack trace.
It is also used by various kernel debugging features that require
stack trace generation.
config DEBUG_KOBJECT
bool "kobject debugging"
depends on DEBUG_KERNEL
help
If you say Y here, some extra kobject debugging messages will be sent
to the syslog.
config DEBUG_KOBJECT_RELEASE
bool "kobject release debugging"
depends on DEBUG_OBJECTS_TIMERS
help
kobjects are reference counted objects. This means that their
last reference count put is not predictable, and the kobject can
live on past the point at which a driver decides to drop it's
initial reference to the kobject gained on allocation. An
example of this would be a struct device which has just been
unregistered.
However, some buggy drivers assume that after such an operation,
the memory backing the kobject can be immediately freed. This
goes completely against the principles of a refcounted object.
If you say Y here, the kernel will delay the release of kobjects
on the last reference count to improve the visibility of this
kind of kobject release bug.
config HAVE_DEBUG_BUGVERBOSE
bool
config DEBUG_BUGVERBOSE
bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
default y
help
Say Y here to make BUG() panics output the file name and line number
of the BUG call as well as the EIP and oops trace. This aids
debugging but costs about 70-100K of memory.
config DEBUG_LIST
bool "Debug linked list manipulation"
depends on DEBUG_KERNEL
help
Enable this to turn on extended checks in the linked-list
walking routines.
If unsure, say N.
config DEBUG_PI_LIST
bool "Debug priority linked list manipulation"
depends on DEBUG_KERNEL
help
Enable this to turn on extended checks in the priority-ordered
linked-list (plist) walking routines. This checks the entire
list multiple times during each manipulation.
If unsure, say N.
config DEBUG_SG
bool "Debug SG table operations"
depends on DEBUG_KERNEL
help
Enable this to turn on checks on scatter-gather tables. This can
help find problems with drivers that do not properly initialize
their sg tables.
If unsure, say N.
config DEBUG_NOTIFIERS
bool "Debug notifier call chains"
depends on DEBUG_KERNEL
help
Enable this to turn on sanity checking for notifier call chains.
This is most useful for kernel developers to make sure that
modules properly unregister themselves from notifier chains.
This is a relatively cheap check but if you care about maximum
performance, say N.
config DEBUG_CREDENTIALS
bool "Debug credential management"
depends on DEBUG_KERNEL
help
Enable this to turn on some debug checking for credential
management. The additional code keeps track of the number of
pointers from task_structs to any given cred struct, and checks to
see that this number never exceeds the usage count of the cred
struct.
Furthermore, if SELinux is enabled, this also checks that the
security pointer in the cred struct is never seen to be invalid.
If unsure, say N.
menu "RCU Debugging"
config PROVE_RCU
def_bool PROVE_LOCKING
config PROVE_RCU_REPEATEDLY
bool "RCU debugging: don't disable PROVE_RCU on first splat"
depends on PROVE_RCU
default n
help
By itself, PROVE_RCU will disable checking upon issuing the
first warning (or "splat"). This feature prevents such
disabling, allowing multiple RCU-lockdep warnings to be printed
on a single reboot.
Say Y to allow multiple RCU-lockdep warnings per boot.
Say N if you are unsure.
config SPARSE_RCU_POINTER
bool "RCU debugging: sparse-based checks for pointer usage"
default n
help
This feature enables the __rcu sparse annotation for
RCU-protected pointers. This annotation will cause sparse
to flag any non-RCU used of annotated pointers. This can be
helpful when debugging RCU usage. Please note that this feature
is not intended to enforce code cleanliness; it is instead merely
a debugging aid.
Say Y to make sparse flag questionable use of RCU-protected pointers
Say N if you are unsure.
config TORTURE_TEST
tristate
default n
config RCU_TORTURE_TEST
tristate "torture tests for RCU"
depends on DEBUG_KERNEL
select TORTURE_TEST
select SRCU
select TASKS_RCU
default n
help
This option provides a kernel module that runs torture tests
on the RCU infrastructure. The kernel module may be built
after the fact on the running kernel to be tested, if desired.
Say Y here if you want RCU torture tests to be built into
the kernel.
Say M if you want the RCU torture tests to build as a module.
Say N if you are unsure.
config RCU_TORTURE_TEST_RUNNABLE
bool "torture tests for RCU runnable by default"
depends on RCU_TORTURE_TEST = y
default n
help
This option provides a way to build the RCU torture tests
directly into the kernel without them starting up at boot
time. You can use /proc/sys/kernel/rcutorture_runnable
to manually override this setting. This /proc file is
available only when the RCU torture tests have been built
into the kernel.
Say Y here if you want the RCU torture tests to start during
boot (you probably don't).
Say N here if you want the RCU torture tests to start only
after being manually enabled via /proc.
config RCU_TORTURE_TEST_SLOW_PREINIT
bool "Slow down RCU grace-period pre-initialization to expose races"
depends on RCU_TORTURE_TEST
help
This option delays grace-period pre-initialization (the
propagation of CPU-hotplug changes up the rcu_node combining
tree) for a few jiffies between initializing each pair of
consecutive rcu_node structures. This helps to expose races
involving grace-period pre-initialization, in other words, it
makes your kernel less stable. It can also greatly increase
grace-period latency, especially on systems with large numbers
of CPUs. This is useful when torture-testing RCU, but in
almost no other circumstance.
Say Y here if you want your system to crash and hang more often.
Say N if you want a sane system.
config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
int "How much to slow down RCU grace-period pre-initialization"
range 0 5
default 3
depends on RCU_TORTURE_TEST_SLOW_PREINIT
help
This option specifies the number of jiffies to wait between
each rcu_node structure pre-initialization step.
config RCU_TORTURE_TEST_SLOW_INIT
bool "Slow down RCU grace-period initialization to expose races"
depends on RCU_TORTURE_TEST
help
This option delays grace-period initialization for a few
jiffies between initializing each pair of consecutive
rcu_node structures. This helps to expose races involving
grace-period initialization, in other words, it makes your
kernel less stable. It can also greatly increase grace-period
latency, especially on systems with large numbers of CPUs.
This is useful when torture-testing RCU, but in almost no
other circumstance.
Say Y here if you want your system to crash and hang more often.
Say N if you want a sane system.
config RCU_TORTURE_TEST_SLOW_INIT_DELAY
int "How much to slow down RCU grace-period initialization"
range 0 5
default 3
rcu: Control grace-period delays directly from value In a misguided attempt to avoid an #ifdef, the use of the gp_init_delay module parameter was conditioned on the corresponding RCU_TORTURE_TEST_SLOW_INIT Kconfig variable, using IS_ENABLED() at the point of use in the code. This meant that the compiler always saw the delay, which meant that RCU_TORTURE_TEST_SLOW_INIT_DELAY had to be unconditionally defined. This in turn caused "make oldconfig" to ask pointless questions about the value of RCU_TORTURE_TEST_SLOW_INIT_DELAY in cases where it was not even used. This commit avoids these pointless questions by defining gp_init_delay under #ifdef. In one branch, gp_init_delay is initialized to RCU_TORTURE_TEST_SLOW_INIT_DELAY and is also a module parameter (thus allowing boot-time modification), and in the other branch gp_init_delay is a const variable initialized by default to zero. This approach also simplifies the code at the delay point by eliminating the IS_DEFINED(). Because gp_init_delay is constant zero in the no-delay case intended for production use, the "gp_init_delay > 0" check causes the delay to become dead code, as desired in this case. In addition, this commit replaces magic constant "10" with the preprocessor variable PER_RCU_NODE_PERIOD, which controls the number of grace periods that are allowed to elapse at full speed before a delay is inserted. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-04-15 10:33:59 +08:00
depends on RCU_TORTURE_TEST_SLOW_INIT
help
This option specifies the number of jiffies to wait between
each rcu_node structure initialization.
config RCU_TORTURE_TEST_SLOW_CLEANUP
bool "Slow down RCU grace-period cleanup to expose races"
depends on RCU_TORTURE_TEST
help
This option delays grace-period cleanup for a few jiffies
between cleaning up each pair of consecutive rcu_node
structures. This helps to expose races involving grace-period
cleanup, in other words, it makes your kernel less stable.
It can also greatly increase grace-period latency, especially
on systems with large numbers of CPUs. This is useful when
torture-testing RCU, but in almost no other circumstance.
Say Y here if you want your system to crash and hang more often.
Say N if you want a sane system.
config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
int "How much to slow down RCU grace-period cleanup"
range 0 5
default 3
depends on RCU_TORTURE_TEST_SLOW_CLEANUP
help
This option specifies the number of jiffies to wait between
each rcu_node structure cleanup operation.
config RCU_CPU_STALL_TIMEOUT
int "RCU CPU stall timeout in seconds"
depends on RCU_STALL_COMMON
range 3 300
default 21
help
If a given RCU grace period extends more than the specified
number of seconds, a CPU stall warning is printed. If the
RCU grace period persists, additional CPU stall warnings are
printed at more widely spaced intervals.
config RCU_TRACE
bool "Enable tracing for RCU"
depends on DEBUG_KERNEL
select TRACE_CLOCK
help
This option provides tracing in RCU which presents stats
in debugfs for debugging RCU implementation.
Say Y here if you want to enable RCU tracing
Say N if you are unsure.
config RCU_EQS_DEBUG
bool "Provide debugging asserts for adding NO_HZ support to an arch"
depends on DEBUG_KERNEL
help
This option provides consistency checks in RCU's handling of
NO_HZ. These checks have proven quite helpful in detecting
bugs in arch-specific NO_HZ code.
Say N here if you need ultimate kernel/user switch latencies
Say Y if you are unsure
endmenu # "RCU Debugging"
config DEBUG_WQ_FORCE_RR_CPU
bool "Force round-robin CPU selection for unbound work items"
depends on DEBUG_KERNEL
default n
help
Workqueue used to implicitly guarantee that work items queued
without explicit CPU specified are put on the local CPU. This
guarantee is no longer true and while local CPU is still
preferred work items may be put on foreign CPUs. Kernel
parameter "workqueue.debug_force_rr_cpu" is added to force
round-robin CPU selection to flush out usages which depend on the
now broken guarantee. This config option enables the debug
feature by default. When enabled, memory and cache locality will
be impacted.
config DEBUG_BLOCK_EXT_DEVT
bool "Force extended block device numbers and spread them"
depends on DEBUG_KERNEL
depends on BLOCK
default n
help
BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
YOU ARE DOING. Distros, please enable this and fix whatever
is broken.
Conventionally, block device numbers are allocated from
predetermined contiguous area. However, extended block area
may introduce non-contiguous block device numbers. This
option forces most block device numbers to be allocated from
the extended space and spreads them to discover kernel or
userland code paths which assume predetermined contiguous
device number allocation.
Note that turning on this debug option shuffles all the
device numbers for all IDE and SCSI devices including libata
ones, so root partition specified using device number
directly (via rdev or root=MAJ:MIN) won't work anymore.
Textual device names (root=/dev/sdXn) will continue to work.
Say N if you are unsure.
fault-injection: notifier error injection This patchset provides kernel modules that can be used to test the error handling of notifier call chain failures by injecting artifical errors to the following notifier chain callbacks. * CPU notifier * PM notifier * memory hotplug notifier * powerpc pSeries reconfig notifier Example: Inject CPU offline error (-1 == -EPERM) # cd /sys/kernel/debug/notifier-error-inject/cpu # echo -1 > actions/CPU_DOWN_PREPARE/error # echo 0 > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Operation not permitted The patchset also adds cpu and memory hotplug tests to tools/testing/selftests These tests first do simple online and offline test and then do fault injection tests if notifier error injection module is available. This patch: The notifier error injection provides the ability to inject artifical errors to specified notifier chain callbacks. It is useful to test the error handling of notifier call chain failures. This adds common basic functions to define which type of events can be fail and to initialize the debugfs interface to control what error code should be returned and which event should be failed. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 05:43:02 +08:00
config NOTIFIER_ERROR_INJECTION
tristate "Notifier error injection"
depends on DEBUG_KERNEL
select DEBUG_FS
help
This option provides the ability to inject artificial errors to
fault-injection: notifier error injection This patchset provides kernel modules that can be used to test the error handling of notifier call chain failures by injecting artifical errors to the following notifier chain callbacks. * CPU notifier * PM notifier * memory hotplug notifier * powerpc pSeries reconfig notifier Example: Inject CPU offline error (-1 == -EPERM) # cd /sys/kernel/debug/notifier-error-inject/cpu # echo -1 > actions/CPU_DOWN_PREPARE/error # echo 0 > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Operation not permitted The patchset also adds cpu and memory hotplug tests to tools/testing/selftests These tests first do simple online and offline test and then do fault injection tests if notifier error injection module is available. This patch: The notifier error injection provides the ability to inject artifical errors to specified notifier chain callbacks. It is useful to test the error handling of notifier call chain failures. This adds common basic functions to define which type of events can be fail and to initialize the debugfs interface to control what error code should be returned and which event should be failed. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 05:43:02 +08:00
specified notifier chain callbacks. It is useful to test the error
handling of notifier call chain failures.
Say N if unsure.
config CPU_NOTIFIER_ERROR_INJECT
tristate "CPU notifier error injection module"
cpu: rewrite cpu-notifier-error-inject module Rewrite existing cpu-notifier-error-inject module to use debugfs based new framework. This change removes cpu_up_prepare_error and cpu_down_prepare_error module parameters which were used to specify error code to be injected. We could keep these module parameters for backward compatibility by module_param_cb but it seems overkill for this module. This provides the ability to inject artifical errors to CPU notifier chain callbacks. It is controlled through debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu If the notifier call chain should be failed with some events notified, write the error code to "actions/<notifier event>/error". Example1: inject CPU offline error (-1 == -EPERM) # cd /sys/kernel/debug/notifier-error-inject/cpu # echo -1 > actions/CPU_DOWN_PREPARE/error # echo 0 > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Operation not permitted Example2: inject CPU online error (-2 == -ENOENT) # cd /sys/kernel/debug/notifier-error-inject/cpu # echo -2 > actions/CPU_UP_PREPARE/error # echo 1 > /sys/devices/system/cpu/cpu1/online bash: echo: write error: No such file or directory Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 05:43:03 +08:00
depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
help
This option provides a kernel module that can be used to test
the error handling of the cpu notifiers by injecting artificial
cpu: rewrite cpu-notifier-error-inject module Rewrite existing cpu-notifier-error-inject module to use debugfs based new framework. This change removes cpu_up_prepare_error and cpu_down_prepare_error module parameters which were used to specify error code to be injected. We could keep these module parameters for backward compatibility by module_param_cb but it seems overkill for this module. This provides the ability to inject artifical errors to CPU notifier chain callbacks. It is controlled through debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu If the notifier call chain should be failed with some events notified, write the error code to "actions/<notifier event>/error". Example1: inject CPU offline error (-1 == -EPERM) # cd /sys/kernel/debug/notifier-error-inject/cpu # echo -1 > actions/CPU_DOWN_PREPARE/error # echo 0 > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Operation not permitted Example2: inject CPU online error (-2 == -ENOENT) # cd /sys/kernel/debug/notifier-error-inject/cpu # echo -2 > actions/CPU_UP_PREPARE/error # echo 1 > /sys/devices/system/cpu/cpu1/online bash: echo: write error: No such file or directory Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 05:43:03 +08:00
errors to CPU notifier chain callbacks. It is controlled through
debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
Example: Inject CPU offline error (-1 == -EPERM)
# cd /sys/kernel/debug/notifier-error-inject/cpu
# echo -1 > actions/CPU_DOWN_PREPARE/error
# echo 0 > /sys/devices/system/cpu/cpu1/online
bash: echo: write error: Operation not permitted
To compile this code as a module, choose M here: the module will
be called cpu-notifier-error-inject.
If unsure, say N.
config PM_NOTIFIER_ERROR_INJECT
tristate "PM notifier error injection module"
depends on PM && NOTIFIER_ERROR_INJECTION
default m if PM_DEBUG
help
This option provides the ability to inject artificial errors to
PM notifier chain callbacks. It is controlled through debugfs
interface /sys/kernel/debug/notifier-error-inject/pm
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
Example: Inject PM suspend error (-12 = -ENOMEM)
# cd /sys/kernel/debug/notifier-error-inject/pm/
# echo -12 > actions/PM_SUSPEND_PREPARE/error
# echo mem > /sys/power/state
bash: echo: write error: Cannot allocate memory
To compile this code as a module, choose M here: the module will
be called pm-notifier-error-inject.
If unsure, say N.
config OF_RECONFIG_NOTIFIER_ERROR_INJECT
tristate "OF reconfig notifier error injection module"
depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
help
This option provides the ability to inject artificial errors to
OF reconfig notifier chain callbacks. It is controlled
through debugfs interface under
/sys/kernel/debug/notifier-error-inject/OF-reconfig/
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
To compile this code as a module, choose M here: the module will
be called of-reconfig-notifier-error-inject.
If unsure, say N.
config NETDEV_NOTIFIER_ERROR_INJECT
tristate "Netdev notifier error injection module"
depends on NET && NOTIFIER_ERROR_INJECTION
help
This option provides the ability to inject artificial errors to
netdevice notifier chain callbacks. It is controlled through debugfs
interface /sys/kernel/debug/notifier-error-inject/netdev
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
Example: Inject netdevice mtu change error (-22 = -EINVAL)
# cd /sys/kernel/debug/notifier-error-inject/netdev
# echo -22 > actions/NETDEV_CHANGEMTU/error
# ip link set eth0 mtu 1024
RTNETLINK answers: Invalid argument
To compile this code as a module, choose M here: the module will
be called netdev-notifier-error-inject.
If unsure, say N.
config FAULT_INJECTION
bool "Fault-injection framework"
depends on DEBUG_KERNEL
help
Provide fault-injection framework.
For more details, see Documentation/fault-injection/.
config FAILSLAB
bool "Fault-injection capability for kmalloc"
depends on FAULT_INJECTION
depends on SLAB || SLUB
help
Provide fault-injection capability for kmalloc.
config FAIL_PAGE_ALLOC
bool "Fault-injection capabilitiy for alloc_pages()"
depends on FAULT_INJECTION
help
Provide fault-injection capability for alloc_pages().
config FAIL_MAKE_REQUEST
bool "Fault-injection capability for disk IO"
depends on FAULT_INJECTION && BLOCK
help
Provide fault-injection capability for disk IO.
config FAIL_IO_TIMEOUT
bool "Fault-injection capability for faking disk interrupts"
depends on FAULT_INJECTION && BLOCK
help
Provide fault-injection capability on end IO handling. This
will make the block layer "forget" an interrupt as configured,
thus exercising the error handling.
Only works with drivers that use the generic timeout handling,
for others it wont do anything.
config FAIL_MMC_REQUEST
bool "Fault-injection capability for MMC IO"
depends on FAULT_INJECTION_DEBUG_FS && MMC
help
Provide fault-injection capability for MMC IO.
This will make the mmc core return data errors. This is
useful to test the error handling in the mmc block device
and to test how the mmc host driver handles retries from
the block device.
config FAIL_FUTEX
bool "Fault-injection capability for futexes"
select DEBUG_FS
depends on FAULT_INJECTION && FUTEX
help
Provide fault-injection capability for futexes.
config FAULT_INJECTION_DEBUG_FS
bool "Debugfs entries for fault-injection capabilities"
depends on FAULT_INJECTION && SYSFS && DEBUG_FS
help
Enable configuration of fault-injection capabilities via debugfs.
config FAULT_INJECTION_STACKTRACE_FILTER
bool "stacktrace filter for fault-injection capabilities"
depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
depends on !X86_64
select STACKTRACE
select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
help
Provide stacktrace filter for fault-injection capabilities
config LATENCYTOP
bool "Latency measuring infrastructure"
depends on DEBUG_KERNEL
depends on STACKTRACE_SUPPORT
depends on PROC_FS
select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
select KALLSYMS
select KALLSYMS_ALL
select STACKTRACE
select SCHEDSTATS
select SCHED_DEBUG
help
Enable this option if you want to use the LatencyTOP tool
to find out which userspace is blocking on what kernel operations.
Kconfig: consolidate CONFIG_DEBUG_STRICT_USER_COPY_CHECKS The help text for this config is duplicated across the x86, parisc, and s390 Kconfig.debug files. Arnd Bergman noted that the help text was slightly misleading and should be fixed to state that enabling this option isn't a problem when using pre 4.4 gcc. To simplify the rewording, consolidate the text into lib/Kconfig.debug and modify it there to be more explicit about when you should say N to this config. Also, make the text a bit more generic by stating that this option enables compile time checks so we can cover architectures which emit warnings vs. ones which emit errors. The details of how an architecture decided to implement the checks isn't as important as the concept of compile time checking of copy_from_user() calls. While we're doing this, remove all the copy_from_user_overflow() code that's duplicated many times and place it into lib/ so that any architecture supporting this option can get the function for free. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Ingo Molnar <mingo@kernel.org> Acked-by: H. Peter Anvin <hpa@zytor.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Acked-by: Helge Deller <deller@gmx.de> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 06:28:42 +08:00
config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
bool
config DEBUG_STRICT_USER_COPY_CHECKS
bool "Strict user copy size checks"
depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
help
Enabling this option turns a certain set of sanity checks for user
copy operations into compile time failures.
The copy_from_user() etc checks are there to help test if there
are sufficient security checks on the length argument of
the copy operation, by having gcc prove that the argument is
within bounds.
If unsure, say N.
source kernel/trace/Kconfig
menu "Runtime Testing"
config LKDTM
tristate "Linux Kernel Dump Test Tool Module"
depends on DEBUG_FS
depends on BLOCK
default n
help
This module enables testing of the different dumping mechanisms by
inducing system failures at predefined crash points.
If you don't need it: say N
Choose M here to compile this code as a module. The module will be
called lkdtm.
Documentation on how to use the module can be found in
Documentation/fault-injection/provoke-crashes.txt
config TEST_LIST_SORT
bool "Linked list sorting test"
depends on DEBUG_KERNEL
help
Enable this to turn on 'list_sort()' function test. This test is
executed only once during system boot, so affects only boot time.
If unsure, say N.
config KPROBES_SANITY_TEST
bool "Kprobes sanity tests"
depends on DEBUG_KERNEL
depends on KPROBES
default n
help
This option provides for testing basic kprobes functionality on
boot. A sample kprobe, jprobe and kretprobe are inserted and
verified for functionality.
Say N if you are unsure.
config BACKTRACE_SELF_TEST
tristate "Self test for the backtrace code"
depends on DEBUG_KERNEL
default n
help
This option provides a kernel module that can be used to test
the kernel stack backtrace code. This option is not useful
for distributions or general kernels, but only for kernel
developers working on architecture code.
Note that if you want to also test saved backtraces, you will
have to enable STACKTRACE as well.
Say N if you are unsure.
config RBTREE_TEST
tristate "Red-Black tree test"
depends on DEBUG_KERNEL
help
A benchmark measuring the performance of the rbtree library.
Also includes rbtree invariant checks.
rbtree: add prio tree and interval tree tests Patch 1 implements support for interval trees, on top of the augmented rbtree API. It also adds synthetic tests to compare the performance of interval trees vs prio trees. Short answers is that interval trees are slightly faster (~25%) on insert/erase, and much faster (~2.4 - 3x) on search. It is debatable how realistic the synthetic test is, and I have not made such measurements yet, but my impression is that interval trees would still come out faster. Patch 2 uses a preprocessor template to make the interval tree generic, and uses it as a replacement for the vma prio_tree. Patch 3 takes the other prio_tree user, kmemleak, and converts it to use a basic rbtree. We don't actually need the augmented rbtree support here because the intervals are always non-overlapping. Patch 4 removes the now-unused prio tree library. Patch 5 proposes an additional optimization to rb_erase_augmented, now providing it as an inline function so that the augmented callbacks can be inlined in. This provides an additional 5-10% performance improvement for the interval tree insert/erase benchmark. There is a maintainance cost as it exposes augmented rbtree users to some of the rbtree library internals; however I think this cost shouldn't be too high as I expect the augmented rbtree will always have much less users than the base rbtree. I should probably add a quick summary of why I think it makes sense to replace prio trees with augmented rbtree based interval trees now. One of the drivers is that we need augmented rbtrees for Rik's vma gap finding code, and once you have them, it just makes sense to use them for interval trees as well, as this is the simpler and more well known algorithm. prio trees, in comparison, seem *too* clever: they impose an additional 'heap' constraint on the tree, which they use to guarantee a faster worst-case complexity of O(k+log N) for stabbing queries in a well-balanced prio tree, vs O(k*log N) for interval trees (where k=number of matches, N=number of intervals). Now this sounds great, but in practice prio trees don't realize this theorical benefit. First, the additional constraint makes them harder to update, so that the kernel implementation has to simplify things by balancing them like a radix tree, which is not always ideal. Second, the fact that there are both index and heap properties makes both tree manipulation and search more complex, which results in a higher multiplicative time constant. As it turns out, the simple interval tree algorithm ends up running faster than the more clever prio tree. This patch: Add two test modules: - prio_tree_test measures the performance of lib/prio_tree.c, both for insertion/removal and for stabbing searches - interval_tree_test measures the performance of a library of equivalent functionality, built using the augmented rbtree support. In order to support the second test module, lib/interval_tree.c is introduced. It is kept separate from the interval_tree_test main file for two reasons: first we don't want to provide an unfair advantage over prio_tree_test by having everything in a single compilation unit, and second there is the possibility that the interval tree functionality could get some non-test users in kernel over time. Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 07:31:23 +08:00
config INTERVAL_TREE_TEST
tristate "Interval tree test"
depends on m && DEBUG_KERNEL
select INTERVAL_TREE
rbtree: add prio tree and interval tree tests Patch 1 implements support for interval trees, on top of the augmented rbtree API. It also adds synthetic tests to compare the performance of interval trees vs prio trees. Short answers is that interval trees are slightly faster (~25%) on insert/erase, and much faster (~2.4 - 3x) on search. It is debatable how realistic the synthetic test is, and I have not made such measurements yet, but my impression is that interval trees would still come out faster. Patch 2 uses a preprocessor template to make the interval tree generic, and uses it as a replacement for the vma prio_tree. Patch 3 takes the other prio_tree user, kmemleak, and converts it to use a basic rbtree. We don't actually need the augmented rbtree support here because the intervals are always non-overlapping. Patch 4 removes the now-unused prio tree library. Patch 5 proposes an additional optimization to rb_erase_augmented, now providing it as an inline function so that the augmented callbacks can be inlined in. This provides an additional 5-10% performance improvement for the interval tree insert/erase benchmark. There is a maintainance cost as it exposes augmented rbtree users to some of the rbtree library internals; however I think this cost shouldn't be too high as I expect the augmented rbtree will always have much less users than the base rbtree. I should probably add a quick summary of why I think it makes sense to replace prio trees with augmented rbtree based interval trees now. One of the drivers is that we need augmented rbtrees for Rik's vma gap finding code, and once you have them, it just makes sense to use them for interval trees as well, as this is the simpler and more well known algorithm. prio trees, in comparison, seem *too* clever: they impose an additional 'heap' constraint on the tree, which they use to guarantee a faster worst-case complexity of O(k+log N) for stabbing queries in a well-balanced prio tree, vs O(k*log N) for interval trees (where k=number of matches, N=number of intervals). Now this sounds great, but in practice prio trees don't realize this theorical benefit. First, the additional constraint makes them harder to update, so that the kernel implementation has to simplify things by balancing them like a radix tree, which is not always ideal. Second, the fact that there are both index and heap properties makes both tree manipulation and search more complex, which results in a higher multiplicative time constant. As it turns out, the simple interval tree algorithm ends up running faster than the more clever prio tree. This patch: Add two test modules: - prio_tree_test measures the performance of lib/prio_tree.c, both for insertion/removal and for stabbing searches - interval_tree_test measures the performance of a library of equivalent functionality, built using the augmented rbtree support. In order to support the second test module, lib/interval_tree.c is introduced. It is kept separate from the interval_tree_test main file for two reasons: first we don't want to provide an unfair advantage over prio_tree_test by having everything in a single compilation unit, and second there is the possibility that the interval tree functionality could get some non-test users in kernel over time. Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 07:31:23 +08:00
help
A benchmark measuring the performance of the interval tree library
config PERCPU_TEST
tristate "Per cpu operations test"
depends on m && DEBUG_KERNEL
help
Enable this option to build test module which validates per-cpu
operations.
If unsure, say N.
config ATOMIC64_SELFTEST
bool "Perform an atomic64_t self-test at boot"
help
Enable this option to test the atomic64_t functions at boot.
If unsure, say N.
config ASYNC_RAID6_TEST
tristate "Self test for hardware accelerated raid6 recovery"
depends on ASYNC_RAID6_RECOV
select ASYNC_MEMCPY
---help---
This is a one-shot self test that permutes through the
recovery of all the possible two disk failure scenarios for a
N-disk array. Recovery is performed with the asynchronous
raid6 recovery routines, and will optionally use an offload
engine if one is available.
If unsure, say N.
config TEST_HEXDUMP
tristate "Test functions located in the hexdump module at runtime"
config TEST_STRING_HELPERS
tristate "Test functions located in the string_helpers module at runtime"
config TEST_KSTRTOX
tristate "Test kstrto*() family of functions at runtime"
config TEST_PRINTF
tristate "Test printf() family of functions at runtime"
config TEST_BITMAP
tristate "Test bitmap_*() family of functions at runtime"
default n
help
Enable this option to test the bitmap functions at boot.
If unsure, say N.
config TEST_RHASHTABLE
tristate "Perform selftest on resizable hash table"
default n
help
Enable this option to test the rhashtable functions at boot.
If unsure, say N.
endmenu # runtime tests
x86: early boot debugging via FireWire (ohci1394_dma=early) This patch adds a new configuration option, which adds support for a new early_param which gets checked in arch/x86/kernel/setup_{32,64}.c:setup_arch() to decide wether OHCI-1394 FireWire controllers should be initialized and enabled for physical DMA access to allow remote debugging of early problems like issues ACPI or other subsystems which are executed very early. If the config option is not enabled, no code is changed, and if the boot paramenter is not given, no new code is executed, and independent of that, all new code is freed after boot, so the config option can be even enabled in standard, non-debug kernels. With specialized tools, it is then possible to get debugging information from machines which have no serial ports (notebooks) such as the printk buffer contents, or any data which can be referenced from global pointers, if it is stored below the 4GB limit and even memory dumps of of the physical RAM region below the 4GB limit can be taken without any cooperation from the CPU of the host, so the machine can be crashed early, it does not matter. In the extreme, even kernel debuggers can be accessed in this way. I wrote a small kgdb module and an accompanying gdb stub for FireWire which allows to gdb to talk to kgdb using remote remory reads and writes over FireWire. An version of the gdb stub fore FireWire is able to read all global data from a system which is running a a normal kernel without any kernel debugger, without any interruption or support of the system's CPU. That way, e.g. the task struct and so on can be read and even manipulated when the physical DMA access is granted. A HOWTO is included in this patch, in Documentation/debugging-via-ohci1394.txt and I've put a copy online at ftp://ftp.suse.de/private/bk/firewire/docs/debugging-via-ohci1394.txt It also has links to all the tools which are available to make use of it another copy of it is online at: ftp://ftp.suse.de/private/bk/firewire/kernel/ohci1394_dma_early-v2.diff Signed-Off-By: Bernhard Kaindl <bk@suse.de> Tested-By: Thomas Renninger <trenn@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 20:34:11 +08:00
config PROVIDE_OHCI1394_DMA_INIT
bool "Remote debugging over FireWire early on boot"
x86: early boot debugging via FireWire (ohci1394_dma=early) This patch adds a new configuration option, which adds support for a new early_param which gets checked in arch/x86/kernel/setup_{32,64}.c:setup_arch() to decide wether OHCI-1394 FireWire controllers should be initialized and enabled for physical DMA access to allow remote debugging of early problems like issues ACPI or other subsystems which are executed very early. If the config option is not enabled, no code is changed, and if the boot paramenter is not given, no new code is executed, and independent of that, all new code is freed after boot, so the config option can be even enabled in standard, non-debug kernels. With specialized tools, it is then possible to get debugging information from machines which have no serial ports (notebooks) such as the printk buffer contents, or any data which can be referenced from global pointers, if it is stored below the 4GB limit and even memory dumps of of the physical RAM region below the 4GB limit can be taken without any cooperation from the CPU of the host, so the machine can be crashed early, it does not matter. In the extreme, even kernel debuggers can be accessed in this way. I wrote a small kgdb module and an accompanying gdb stub for FireWire which allows to gdb to talk to kgdb using remote remory reads and writes over FireWire. An version of the gdb stub fore FireWire is able to read all global data from a system which is running a a normal kernel without any kernel debugger, without any interruption or support of the system's CPU. That way, e.g. the task struct and so on can be read and even manipulated when the physical DMA access is granted. A HOWTO is included in this patch, in Documentation/debugging-via-ohci1394.txt and I've put a copy online at ftp://ftp.suse.de/private/bk/firewire/docs/debugging-via-ohci1394.txt It also has links to all the tools which are available to make use of it another copy of it is online at: ftp://ftp.suse.de/private/bk/firewire/kernel/ohci1394_dma_early-v2.diff Signed-Off-By: Bernhard Kaindl <bk@suse.de> Tested-By: Thomas Renninger <trenn@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 20:34:11 +08:00
depends on PCI && X86
help
If you want to debug problems which hang or crash the kernel early
on boot and the crashing machine has a FireWire port, you can use
this feature to remotely access the memory of the crashed machine
over FireWire. This employs remote DMA as part of the OHCI1394
specification which is now the standard for FireWire controllers.
With remote DMA, you can monitor the printk buffer remotely using
firescope and access all memory below 4GB using fireproxy from gdb.
Even controlling a kernel debugger is possible using remote DMA.
Usage:
If ohci1394_dma=early is used as boot parameter, it will initialize
all OHCI1394 controllers which are found in the PCI config space.
As all changes to the FireWire bus such as enabling and disabling
devices cause a bus reset and thereby disable remote DMA for all
devices, be sure to have the cable plugged and FireWire enabled on
the debugging host before booting the debug target for debugging.
This code (~1k) is freed after boot. By then, the firewire stack
in charge of the OHCI-1394 controllers should be used instead.
See Documentation/debugging-via-ohci1394.txt for more information.
config BUILD_DOCSRC
bool "Build targets in Documentation/ tree"
depends on HEADERS_CHECK
help
This option attempts to build objects from the source files in the
kernel Documentation/ tree.
Say N if you are unsure.
config DMA_API_DEBUG
bool "Enable debugging of DMA-API usage"
depends on HAVE_DMA_API_DEBUG
help
Enable this option to debug the use of the DMA API by device drivers.
With this option you will be able to detect common bugs in device
drivers like double-freeing of DMA mappings or freeing mappings that
were never allocated.
This also attempts to catch cases where a page owned by DMA is
accessed by the cpu in a way that could cause data corruption. For
example, this enables cow_user_page() to check that the source page is
not undergoing DMA.
This option causes a performance degradation. Use only if you want to
debug device drivers and dma interactions.
If unsure, say N.
driver core: basic infrastructure for per-module dynamic debug messages Base infrastructure to enable per-module debug messages. I've introduced CONFIG_DYNAMIC_PRINTK_DEBUG, which when enabled centralizes control of debugging statements on a per-module basis in one /proc file, currently, <debugfs>/dynamic_printk/modules. When, CONFIG_DYNAMIC_PRINTK_DEBUG, is not set, debugging statements can still be enabled as before, often by defining 'DEBUG' for the proper compilation unit. Thus, this patch set has no affect when CONFIG_DYNAMIC_PRINTK_DEBUG is not set. The infrastructure currently ties into all pr_debug() and dev_dbg() calls. That is, if CONFIG_DYNAMIC_PRINTK_DEBUG is set, all pr_debug() and dev_dbg() calls can be dynamically enabled/disabled on a per-module basis. Future plans include extending this functionality to subsystems, that define their own debug levels and flags. Usage: Dynamic debugging is controlled by the debugfs file, <debugfs>/dynamic_printk/modules. This file contains a list of the modules that can be enabled. The format of the file is as follows: <module_name> <enabled=0/1> . . . <module_name> : Name of the module in which the debug call resides <enabled=0/1> : whether the messages are enabled or not For example: snd_hda_intel enabled=0 fixup enabled=1 driver enabled=0 Enable a module: $echo "set enabled=1 <module_name>" > dynamic_printk/modules Disable a module: $echo "set enabled=0 <module_name>" > dynamic_printk/modules Enable all modules: $echo "set enabled=1 all" > dynamic_printk/modules Disable all modules: $echo "set enabled=0 all" > dynamic_printk/modules Finally, passing "dynamic_printk" at the command line enables debugging for all modules. This mode can be turned off via the above disable command. [gkh: minor cleanups and tweaks to make the build work quietly] Signed-off-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-08-13 04:46:19 +08:00
config TEST_LKM
test: add minimal module for verification testing This is a pair of test modules I'd like to see in the tree. Instead of putting these in lkdtm, where I've been adding various tests that trigger crashes, these don't make sense there since they need to be either distinctly separate, or their pass/fail state don't need to crash the machine. These live in lib/ for now, along with a few other in-kernel test modules, and use the slightly more common "test_" naming convention, instead of "test-". We should likely standardize on the former: $ find . -name 'test_*.c' | grep -v /tools/ | wc -l 4 $ find . -name 'test-*.c' | grep -v /tools/ | wc -l 2 The first is entirely a no-op module, designed to allow simple testing of the module loading and verification interface. It's useful to have a module that has no other uses or dependencies so it can be reliably used for just testing module loading and verification. The second is a module that exercises the user memory access functions, in an effort to make sure that we can quickly catch any regressions in boundary checking (e.g. like what was recently fixed on ARM). This patch (of 2): When doing module loading verification tests (for example, with module signing, or LSM hooks), it is very handy to have a module that can be built on all systems under test, isn't auto-loaded at boot, and has no device or similar dependencies. This creates the "test_module.ko" module for that purpose, which only reports its load and unload to printk. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-24 07:54:37 +08:00
tristate "Test module loading with 'hello world' module"
default n
depends on m
help
This builds the "test_module" module that emits "Hello, world"
on printk when loaded. It is designed to be used for basic
evaluation of the module loading subsystem (for example when
validating module verification). It lacks any extra dependencies,
and will not normally be loaded by the system unless explicitly
requested by name.
If unsure, say N.
config TEST_USER_COPY
tristate "Test user/kernel boundary protections"
default n
depends on m
help
This builds the "test_user_copy" module that runs sanity checks
on the copy_to/from_user infrastructure, making sure basic
user/kernel boundary testing is working. If it fails to load,
a regression has been detected in the user/kernel memory boundary
protections.
If unsure, say N.
config TEST_BPF
tristate "Test BPF filter functionality"
default n
depends on m && NET
help
This builds the "test_bpf" module that runs various test vectors
against the BPF interpreter or BPF JIT compiler depending on the
current setting. This is in particular useful for BPF JIT compiler
development, but also to run regression tests against changes in
the interpreter code. It also enables test stubs for eBPF maps and
verifier used by user space verifier testsuite.
If unsure, say N.
config TEST_FIRMWARE
tristate "Test firmware loading via userspace interface"
default n
depends on FW_LOADER
help
This builds the "test_firmware" module that creates a userspace
interface for testing firmware loading. This can be used to
control the triggering of firmware loading without needing an
actual firmware-using device. The contents can be rechecked by
userspace.
If unsure, say N.
config TEST_UDELAY
tristate "udelay test driver"
default n
help
This builds the "udelay_test" module that helps to make sure
that udelay() is working properly.
If unsure, say N.
config MEMTEST
bool "Memtest"
depends on HAVE_MEMBLOCK
---help---
This option adds a kernel parameter 'memtest', which allows memtest
to be set.
memtest=0, mean disabled; -- default
memtest=1, mean do 1 test pattern;
...
memtest=17, mean do 17 test patterns.
If you are unsure how to answer this question, answer N.
config TEST_STATIC_KEYS
tristate "Test static keys"
default n
depends on m
help
Test the static key interfaces.
If unsure, say N.
source "samples/Kconfig"
source "lib/Kconfig.kgdb"
UBSAN: run-time undefined behavior sanity checker UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-21 07:00:55 +08:00
source "lib/Kconfig.ubsan"
config ARCH_HAS_DEVMEM_IS_ALLOWED
bool
config STRICT_DEVMEM
bool "Filter access to /dev/mem"
depends on MMU
depends on ARCH_HAS_DEVMEM_IS_ALLOWED
default y if TILE || PPC
---help---
If this option is disabled, you allow userspace (root) access to all
of memory, including kernel and userspace memory. Accidental
access to this is obviously disastrous, but specific access can
be used by people debugging the kernel. Note that with PAT support
enabled, even in this case there are restrictions on /dev/mem
use due to the cache aliasing requirements.
restrict /dev/mem to idle io memory ranges This effectively promotes IORESOURCE_BUSY to IORESOURCE_EXCLUSIVE semantics by default. If userspace really believes it is safe to access the memory region it can also perform the extra step of disabling an active driver. This protects device address ranges with read side effects and otherwise directs userspace to use the driver. Persistent memory presents a large "mistake surface" to /dev/mem as now accidental writes can corrupt a filesystem. In general if a device driver is busily using a memory region it already informs other parts of the kernel to not touch it via request_mem_region(). /dev/mem should honor the same safety restriction by default. Debugging a device driver from userspace becomes more difficult with this enabled. Any application using /dev/mem or mmap of sysfs pci resources will now need to perform the extra step of either: 1/ Disabling the driver, for example: echo <device id> > /dev/bus/<parent bus>/drivers/<driver name>/unbind 2/ Rebooting with "iomem=relaxed" on the command line 3/ Recompiling with CONFIG_IO_STRICT_DEVMEM=n Traditional users of /dev/mem like dosemu are unaffected because the first 1MB of memory is not subject to the IO_STRICT_DEVMEM restriction. Legacy X configurations use /dev/mem to talk to graphics hardware, but that functionality has since moved to kernel graphics drivers. Cc: Arnd Bergmann <arnd@arndb.de> Cc: Russell King <linux@arm.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Ingo Molnar <mingo@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-11-24 07:49:03 +08:00
If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
file only allows userspace access to PCI space and the BIOS code and
data regions. This is sufficient for dosemu and X and all common
users of /dev/mem.
If in doubt, say Y.
config IO_STRICT_DEVMEM
bool "Filter I/O access to /dev/mem"
depends on STRICT_DEVMEM
---help---
If this option is disabled, you allow userspace (root) access to all
io-memory regardless of whether a driver is actively using that
range. Accidental access to this is obviously disastrous, but
specific access can be used by people debugging kernel drivers.
If this option is switched on, the /dev/mem file only allows
restrict /dev/mem to idle io memory ranges This effectively promotes IORESOURCE_BUSY to IORESOURCE_EXCLUSIVE semantics by default. If userspace really believes it is safe to access the memory region it can also perform the extra step of disabling an active driver. This protects device address ranges with read side effects and otherwise directs userspace to use the driver. Persistent memory presents a large "mistake surface" to /dev/mem as now accidental writes can corrupt a filesystem. In general if a device driver is busily using a memory region it already informs other parts of the kernel to not touch it via request_mem_region(). /dev/mem should honor the same safety restriction by default. Debugging a device driver from userspace becomes more difficult with this enabled. Any application using /dev/mem or mmap of sysfs pci resources will now need to perform the extra step of either: 1/ Disabling the driver, for example: echo <device id> > /dev/bus/<parent bus>/drivers/<driver name>/unbind 2/ Rebooting with "iomem=relaxed" on the command line 3/ Recompiling with CONFIG_IO_STRICT_DEVMEM=n Traditional users of /dev/mem like dosemu are unaffected because the first 1MB of memory is not subject to the IO_STRICT_DEVMEM restriction. Legacy X configurations use /dev/mem to talk to graphics hardware, but that functionality has since moved to kernel graphics drivers. Cc: Arnd Bergmann <arnd@arndb.de> Cc: Russell King <linux@arm.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Ingo Molnar <mingo@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-11-24 07:49:03 +08:00
userspace access to *idle* io-memory ranges (see /proc/iomem) This
may break traditional users of /dev/mem (dosemu, legacy X, etc...)
if the driver using a given range cannot be disabled.
If in doubt, say Y.