linux-sg2042/Documentation
Prarit Bhargava 9e3961a097 kernel: add panic_on_warn
There have been several times where I have had to rebuild a kernel to
cause a panic when hitting a WARN() in the code in order to get a crash
dump from a system.  Sometimes this is easy to do, other times (such as
in the case of a remote admin) it is not trivial to send new images to
the user.

A much easier method would be a switch to change the WARN() over to a
panic.  This makes debugging easier in that I can now test the actual
image the WARN() was seen on and I do not have to engage in remote
debugging.

This patch adds a panic_on_warn kernel parameter and
/proc/sys/kernel/panic_on_warn calls panic() in the
warn_slowpath_common() path.  The function will still print out the
location of the warning.

An example of the panic_on_warn output:

The first line below is from the WARN_ON() to output the WARN_ON()'s
location.  After that the panic() output is displayed.

    WARNING: CPU: 30 PID: 11698 at /home/prarit/dummy_module/dummy-module.c:25 init_dummy+0x1f/0x30 [dummy_module]()
    Kernel panic - not syncing: panic_on_warn set ...

    CPU: 30 PID: 11698 Comm: insmod Tainted: G        W  OE  3.17.0+ #57
    Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013
     0000000000000000 000000008e3f87df ffff88080f093c38 ffffffff81665190
     0000000000000000 ffffffff818aea3d ffff88080f093cb8 ffffffff8165e2ec
     ffffffff00000008 ffff88080f093cc8 ffff88080f093c68 000000008e3f87df
    Call Trace:
     [<ffffffff81665190>] dump_stack+0x46/0x58
     [<ffffffff8165e2ec>] panic+0xd0/0x204
     [<ffffffffa038e05f>] ? init_dummy+0x1f/0x30 [dummy_module]
     [<ffffffff81076b90>] warn_slowpath_common+0xd0/0xd0
     [<ffffffffa038e040>] ? dummy_greetings+0x40/0x40 [dummy_module]
     [<ffffffff81076c8a>] warn_slowpath_null+0x1a/0x20
     [<ffffffffa038e05f>] init_dummy+0x1f/0x30 [dummy_module]
     [<ffffffff81002144>] do_one_initcall+0xd4/0x210
     [<ffffffff811b52c2>] ? __vunmap+0xc2/0x110
     [<ffffffff810f8889>] load_module+0x16a9/0x1b30
     [<ffffffff810f3d30>] ? store_uevent+0x70/0x70
     [<ffffffff810f49b9>] ? copy_module_from_fd.isra.44+0x129/0x180
     [<ffffffff810f8ec6>] SyS_finit_module+0xa6/0xd0
     [<ffffffff8166cf29>] system_call_fastpath+0x12/0x17

Successfully tested by me.

hpa said: There is another very valid use for this: many operators would
rather a machine shuts down than being potentially compromised either
functionally or security-wise.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-10 17:41:10 -08:00
..
ABI IB/srp: Add multichannel support 2014-11-12 12:05:24 +01:00
DocBook Merge tag 'docs-for-linus' of git://git.lwn.net/linux-2.6 2014-10-31 11:55:40 -07:00
EDID drm: Add 800x600 (SVGA) screen resolution to the built-in EDIDs 2014-05-26 12:53:40 +10:00
PCI doc: replace "practise" with "practice" in Documentation 2014-06-19 15:28:56 +02:00
RCU Merge branches 'torture.2014.11.03a', 'cpu.2014.11.03a', 'doc.2014.11.13a', 'fixes.2014.11.13a', 'signal.2014.10.29a' and 'rt.2014.10.29a' into HEAD 2014-11-13 10:39:04 -08:00
accounting Documentation: use subdir-y to avoid unnecessary built-in.o files 2014-09-26 11:02:55 +02:00
acpi mfd: Add ACPI support 2014-09-26 08:24:05 +01:00
aoe
arm Allwinner Core Additions for 3.19 2014-11-20 17:23:57 +01:00
arm64 arm64: Emulate CP15 Barrier instructions 2014-11-20 16:34:48 +00:00
auxdisplay Documentation: use subdir-y to avoid unnecessary built-in.o files 2014-09-26 11:02:55 +02:00
backlight backlight: lp855x_bl: support new LP8555 device 2013-11-13 12:09:14 +09:00
blackfin Documentation: add makefiles for more targets 2014-09-26 11:02:56 +02:00
block scsi: add new scsi-command flag for tagged commands 2014-11-12 11:19:40 +01:00
blockdev zram: report maximum used memory 2014-10-09 22:26:02 -04:00
bus-devices
cdrom
cgroups mm: embed the memcg pointer directly into struct page 2014-12-10 17:41:09 -08:00
connector w1: optional bundling of netlink kernel replies 2014-05-27 13:56:21 -07:00
console
cpu-freq intel_pstate: Update documentation of {max,min}_perf_pct sysfs files 2014-07-07 01:22:19 +02:00
cpuidle cpuidle: remove cpuidle_unregister_governor() 2013-10-30 01:21:24 +01:00
cris
crypto
development-process Documentation: remove outdated references to the linux-next wiki 2014-10-28 09:06:11 -04:00
device-mapper dm cache policy mq: simplify ability to promote sequential IO to the cache 2014-11-10 15:25:30 -05:00
devicetree Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 08:38:57 -08:00
driver-model PCI changes for the v3.18 merge window: 2014-10-09 15:03:49 -04:00
dvb [media] get_dvb_firmware: Update firmware of ITEtech IT9135 2014-09-21 17:03:04 -03:00
early-userspace
extcon extcon: fix switch class porting guide (Documentation) 2014-01-07 11:54:28 +09:00
fault-injection
fb doc: spelling error changes 2014-05-05 15:32:05 +02:00
filesystems ovl: rename filesystem type to "overlay" 2014-11-20 16:39:59 +01:00
firmware_class doc: fix minor typos in firmware_class README 2014-07-17 18:43:40 -07:00
fmc FMC: make eeprom attribute writable 2014-02-28 15:12:08 -08:00
frv
gpio This is the bulk of GPIO changes for the v3.18 development 2014-10-09 14:58:15 -04:00
hid HID: uhid: update documentation 2014-08-25 03:28:09 -05:00
hwmon hwmon: (tmp401) Detect TMP435 on all addresses it supports 2014-12-08 06:48:37 -08:00
i2c i2c: i801: Add Device IDs for Intel Sunrise Point PCH 2014-10-16 09:16:22 +02:00
i2o
ia64 Documentation: use subdir-y to avoid unnecessary built-in.o files 2014-09-26 11:02:55 +02:00
ide Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
infiniband IB/mad: add new ioctl to ABI to support new registration options 2014-08-10 20:36:00 -07:00
input Input: elantech - update the documentation 2014-11-13 17:50:23 -08:00
ioctl cxl: Add documentation for userspace APIs 2014-10-08 20:16:19 +11:00
isdn
ja_JP Documentation: Update stable address in Chinese and Japanese translations 2014-04-16 14:13:27 -07:00
kbuild Documentation: kbuild: Improve grammar 2014-08-19 10:02:56 +02:00
kdump kernel: add panic_on_warn 2014-12-10 17:41:10 -08:00
ko_KR Documentation: HOWTO: Updates on subsystem trees, patchwork, -next (vs. -mm) in ko_KR 2014-01-08 15:32:51 -08:00
laptops Documentation: update .gitignore files 2014-09-26 11:02:59 +02:00
leds Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
locking Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-09 19:59:22 -08:00
m68k Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
memory-devices
metag
mic Documentation: update include path for mpssd 2014-10-03 15:48:20 +02:00
mips Documentation: au1xxx-ide.c has moved 2014-08-26 09:35:53 +02:00
misc-devices Documentation: use subdir-y to avoid unnecessary built-in.o files 2014-09-26 11:02:55 +02:00
mmc
mn10300
mtd MTD updates for 3.16: 2014-06-11 08:35:34 -07:00
namespaces
netlabel
networking net-timestamp: Fix a documentation typo 2014-11-25 13:35:26 -05:00
nfc
nios2 Documentation: Add documentation for Nios2 architecture 2014-12-08 12:56:06 +08:00
parisc
pcmcia Documentation: use subdir-y to avoid unnecessary built-in.o files 2014-09-26 11:02:55 +02:00
phy phy: Add new Exynos USB 2.0 PHY driver 2014-03-08 12:39:44 +05:30
platform Documentation: Add list of laptop models supported by the Compal driver 2014-06-10 19:11:06 -04:00
power Merge branch 'pm-qos' 2014-10-23 23:02:36 +02:00
powerpc cxl: Add documentation for userspace APIs 2014-10-08 20:16:19 +11:00
pps
prctl Documentation: Restrict TSC test code to x86 2014-10-28 08:46:27 -04:00
pti
ptp ptp: restore the makefile for building the test program. 2014-10-24 16:07:10 -04:00
rapidio rapidio/tsi721_dma: rework scatter-gather list handling 2014-08-08 15:57:24 -07:00
s390 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial into next 2014-06-04 08:50:34 -07:00
scheduler Documentation/scheduler/sched-deadline.txt: Add minimal main() appendix 2014-09-16 10:23:45 +02:00
scsi libsas: remove task_collector mode 2014-11-27 16:40:24 +01:00
security Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2014-10-12 10:13:55 -04:00
serial TTY/Serial driver patches for 3.18-rc1 2014-10-08 06:52:11 -04:00
sh
sound ALSA: virtuoso: add Xonar Essence STX II support 2014-08-04 15:20:48 +02:00
spi Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/doc 2014-10-07 21:14:57 -04:00
sysctl kernel: add panic_on_warn 2014-12-10 17:41:10 -08:00
target target: Add documentation on the target userspace pass-through driver 2014-10-02 21:35:54 -07:00
thermal drm/nouveau/doc: update the thermal documentation 2014-06-17 14:50:17 +10:00
timers Documentation: update .gitignore files 2014-09-26 11:02:59 +02:00
tpm
trace mm: trace-vmscan-postprocess.pl: report the number of file/anon pages respectively 2014-08-06 18:01:20 -07:00
usb usb: hub: rename khubd to hub_wq in documentation and comments 2014-09-23 22:33:19 -07:00
vDSO vdso: don't require 64-bit math in standalone test 2014-10-25 10:53:44 -04:00
video4linux [media] vivid: default to single planar device instances 2014-11-03 14:43:26 -02:00
virtual Changes for KVM for arm/arm64 for 3.18 2014-09-27 11:03:33 +02:00
vm Docs: Document that the sticky bit is understood by hugetlbfs 2014-10-22 14:26:04 -04:00
w1 w1: new w1_ds2406 driver 2014-06-19 17:45:14 -07:00
watchdog Documentation: use subdir-y to avoid unnecessary built-in.o files 2014-09-26 11:02:55 +02:00
wimax
x86 x86, mpx: Add documentation on Intel MPX 2014-11-18 00:58:54 +01:00
xtensa xtensa: remap io area defined in device tree 2014-01-15 00:25:14 +04:00
zh_CN Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-08-06 21:03:53 -07:00
00-INDEX locking/Documentation: Move locking related docs into Documentation/locking/ 2014-08-13 10:32:03 +02:00
BUG-HUNTING
Changes Documentation: remove obsolete pcmcia-cs from Changes 2014-09-09 10:35:58 +02:00
CodingStyle CodingStyle: fix a minor typo 2014-08-26 09:35:54 +02:00
DMA-API-HOWTO.txt Documentation: correct parameter error for dma_mapping_error 2014-09-26 11:22:29 +02:00
DMA-API.txt DMA-API: Capitalize "CPU" consistently 2014-05-26 17:28:27 -06:00
DMA-ISA-LPC.txt DMA-API: Clarify physical/bus address distinction 2014-05-20 16:54:21 -06:00
DMA-attributes.txt doc: spelling error changes 2014-05-05 15:32:05 +02:00
HOWTO Documentation: remove outdated references to the linux-next wiki 2014-10-28 09:06:11 -04:00
IPMI.txt
IRQ-affinity.txt
IRQ-domain.txt irqdomain: Introduce new interfaces to support hierarchy irqdomains 2014-11-23 13:01:45 +01:00
IRQ.txt
Intel-IOMMU.txt
Makefile Documentation: add makefiles for more targets 2014-09-26 11:02:56 +02:00
ManagementStyle
SAK.txt
SM501.txt
SecurityBugs
SubmitChecklist
SubmittingDrivers doc: SubmittingPatches: remove dead link, kerneltrap.org no longer works 2014-06-19 15:15:27 +02:00
SubmittingPatches Documentation/SubmittingPatches: Reported-by tags and permission 2014-10-29 08:56:46 -04:00
VGA-softcursor.txt
applying-patches.txt Documentation: change "&" to "and" in Documentation/applying-patches.txt 2014-09-26 11:10:11 +02:00
assoc_array.txt KEYS: Fix multiple key add into associative array 2013-12-02 11:24:18 +00:00
atomic_ops.txt documentation: Add atomic_long_t to atomic_ops.txt 2014-11-13 10:34:54 -08:00
bad_memory.txt
basic_profiling.txt
bcache.txt
binfmt_misc.txt binfmt_misc: touch up documentation a bit 2014-10-14 02:18:16 +02:00
braille-console.txt
bt8xxgpio.txt
btmrvl.txt
bus-virt-phys-mapping.txt
cachetlb.txt
circular-buffers.txt documentation: Update circular buffer for load-acquire/store-release 2013-12-03 10:08:57 -08:00
clk.txt clk: Improve clk_ops documentation 2014-05-12 17:08:33 -07:00
coccinelle.txt
cpu-hotplug.txt Doc/cpu-hotplug: Specify race-free way to register CPU hotplug callbacks 2014-03-20 13:43:40 +01:00
cpu-load.txt
cputopology.txt
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt firewire: revert to 4 GB RDMA, fix protocols using Memory Space 2014-05-29 15:50:30 +02:00
dell_rbu.txt
devices.txt Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2014-04-04 09:50:07 -07:00
digsig.txt
dma-buf-sharing.txt Documentation/dma-buf-sharing.txt: update API descriptions 2014-08-28 11:57:24 +05:30
dmaengine.txt dmaengine: Update documentation for inline wrapper 2014-08-28 12:37:55 +05:30
dmatest.txt dmatest: add a 'wait' parameter 2013-11-14 11:04:40 -08:00
dontdiff Documentation: LLVMLinux: Update Documentation/dontdiff 2014-04-09 13:44:34 -07:00
dynamic-debug-howto.txt doc: spelling error changes 2014-05-05 15:32:05 +02:00
edac.txt Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial into next 2014-06-04 08:50:34 -07:00
efi-stub.txt doc: arm64: add description of EFI stub support 2014-04-30 19:57:05 +01:00
eisa.txt
email-clients.txt Documentation: add section about git to email-clients.txt 2014-06-29 13:38:33 -07:00
flexible-arrays.txt
futex-requeue-pi.txt doc: fix double words 2014-03-21 13:16:58 +01:00
gcov.txt gcov: compile specific gcov implementation based on gcc version 2013-11-13 12:09:34 +09:00
highuid.txt
hsi.txt Documentation: HSI: Add some general description for the HSI subsystem 2014-05-04 09:49:46 +02:00
hw_random.txt
hwspinlock.txt
init.txt
initrd.txt
intel_txt.txt
io-mapping.txt doc: fix some typos 2013-12-02 14:48:28 +01:00
io_ordering.txt
iostats.txt
irqflags-tracing.txt asm/system.h: clean asm/system.h from docs 2014-04-07 16:36:11 -07:00
isapnp.txt
java.txt Documentation: update java sample wrapper for java 7 2014-05-25 12:39:00 -07:00
kernel-doc-nano-HOWTO.txt
kernel-docs.txt
kernel-parameters.txt kernel: add panic_on_warn 2014-12-10 17:41:10 -08:00
kernel-per-CPU-kthreads.txt Documentation/kernel-per-CPU-kthreads.txt: Workqueue affinity 2014-02-17 14:56:08 -08:00
kmemcheck.txt doc: fix double words 2014-03-21 13:16:58 +01:00
kmemleak.txt Documentation: Add CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF case 2014-10-24 13:59:03 -04:00
kobject.txt kobject: remove kset from sysfs immediately in kset_unregister() 2013-12-07 21:20:11 -08:00
kprobes.txt Documentation/kprobes: add s390 to list of supported architectures 2014-09-09 08:53:27 +02:00
kref.txt
ldm.txt
local_ops.txt
lockup-watchdogs.txt lockup-watchdogs: Fix a typo 2014-08-26 09:35:52 +02:00
logo.gif
logo.txt
lzo.txt Documentation: lzo: document part of the encoding 2014-09-28 11:08:00 +02:00
magic-number.txt Documentation/serial: Delete obsolete driver documentation 2014-04-16 14:20:34 -07:00
mailbox.txt doc: add documentation for mailbox framework 2014-10-08 10:39:41 +05:30
md.txt doc: fix some typos in documentations 2013-12-02 14:45:19 +01:00
media-framework.txt
memory-barriers.txt Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-09 20:23:19 -08:00
memory-hotplug.txt memory-hotplug: add sysfs valid_zones attribute 2014-10-09 22:25:52 -04:00
module-signing.txt Nothing major: the stricter permissions checking for sysfs broke 2014-04-06 09:38:07 -07:00
mono.txt
nommu-mmap.txt
numastat.txt
oops-tracing.txt panic: add TAINT_SOFTLOCKUP 2014-08-08 15:57:24 -07:00
padata.txt
parport-lowlevel.txt
parport.txt
percpu-rw-semaphore.txt
phy.txt phy: core: Let node ptr of PHY point to PHY and not of PHY provider 2014-07-22 12:46:11 +05:30
pi-futex.txt
pinctrl.txt pinctrl: clean up after enable refactoring 2014-09-04 10:05:07 +02:00
pnp.txt
preempt-locking.txt
printk-formats.txt lib/vsprintf: add %*pE[achnops] format specifier 2014-10-14 02:18:26 +02:00
pwm.txt pwm: modify PWM_LOOKUP to initialize all struct pwm_lookup members 2014-05-21 11:19:36 +02:00
ramoops.txt
rbtree.txt doc: spelling error changes 2014-05-05 15:32:05 +02:00
remoteproc.txt
rfkill.txt doc: spelling error changes 2014-05-05 15:32:05 +02:00
robust-futex-ABI.txt Documentation/robust-futex-API: Count properly to 4 2013-11-30 14:08:28 +01:00
robust-futexes.txt doc: spelling error changes 2014-05-05 15:32:05 +02:00
rpmsg.txt
rtc.txt
serial-console.txt
sgi-ioc4.txt
smsc_ece1099.txt
sparse.txt
stable_api_nonsense.txt
stable_kernel_rules.txt stable_kernel_rules: Add pointer to netdev-FAQ for network patches 2014-07-09 15:54:27 -07:00
static-keys.txt doc: fix some typos in documentations 2013-12-02 14:45:19 +01:00
svga.txt
sysfs-rules.txt Documentation/sysfs-rules.txt: Add device attribute error code documentation 2014-09-19 14:44:51 -07:00
sysrq.txt sysrq: Allow magic SysRq key functions to be disabled through Kconfig 2013-10-16 13:01:44 -07:00
this_cpu_ops.txt Docs: this_cpu_ops: remove redundant add forms 2014-09-26 11:03:00 +02:00
unaligned-memory-access.txt ether_addr_equal: Optimize implementation, remove unused compare_ether_addr 2013-12-06 16:37:43 -05:00
unicode.txt
unshare.txt
vfio.txt drivers/vfio: EEH support for VFIO PCI device 2014-08-05 15:28:48 +10:00
vgaarbiter.txt
video-output.txt
vme_api.txt VME: Rename vme_slot_get to avoid confusion with reference counting 2013-12-03 11:15:58 -08:00
volatile-considered-harmful.txt
workqueue.txt
xillybus.txt xillybus: Move out of staging 2014-09-23 23:44:16 -07:00
xz.txt
zorro.txt zorro/UAPI: Disintegrate include/linux/zorro*.h 2013-11-26 11:09:08 +01:00