Do not use kmalloc() but kmem_cache_alloc() for the allocation
of the kmem_cache structures in slub.
Reviewed-by: Glauber Costa <glommer@parallels.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Add additional debugging to check that the objects is actually from the cache
the caller claims. Doing so currently trips up some other debugging code. It
takes a lot to infer from that what was happening.
Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
[ penberg@kernel.org: Use pr_err() ]
Signed-off-by: Pekka Enberg <penberg@kernel.org>
In current implementation, after unfreezing, we doesn't touch oldpage,
so it remain 'NOT NULL'. When we call this_cpu_cmpxchg()
with this old oldpage, this_cpu_cmpxchg() is mostly be failed.
We can change value of oldpage to NULL after unfreezing,
because unfreeze_partial() ensure that all the cpu partial slabs is removed
from cpu partial list. In this time, we could expect that
this_cpu_cmpxchg is mostly succeed.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Only applies to scenarios where debugging is on:
Validation of slabs can currently occur while debugging
information is updated from the fast paths of the allocator.
This results in various races where we get false reports about
slab metadata not being in order.
This patch makes the fast paths take the node lock so that
serialization with slab validation will occur. Causes additional
slowdown in debug scenarios.
Reported-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
When freeing objects, the slub allocator will most of the time free
empty pages by calling __free_pages(). But high-order kmalloc will be
diposed by means of put_page() instead. It makes no sense to call
put_page() in kernel pages that are provided by the object allocators,
so we shouldn't be doing this ourselves. Aside from the consistency
change, we don't change the flow too much. put_page()'s would call its
dtor function, which is __free_pages. We also already do all of the
Compound page tests ourselves, and the Mlock test we lose don't really
matter.
Signed-off-by: Glauber Costa <glommer@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: David Rientjes <rientjes@google.com>
CC: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This patch removes the check for pfmemalloc from the alloc hotpath and
puts the logic after the election of a new per cpu slab. For a pfmemalloc
page we do not use the fast path but force the use of the slow path which
is also used for the debug case.
This has the side-effect of weakening pfmemalloc processing in the
following way;
1. A process that is allocating for network swap calls __slab_alloc.
pfmemalloc_match is true so the freelist is loaded and c->freelist is
now pointing to a pfmemalloc page.
2. A process that is attempting normal allocations calls slab_alloc,
finds the pfmemalloc page on the freelist and uses it because it did
not check pfmemalloc_match()
The patch allows non-pfmemalloc allocations to use pfmemalloc pages with
the kmalloc slabs being the most vunerable caches on the grounds they
are most likely to have a mix of pfmemalloc and !pfmemalloc requests. A
later patch will still protect the system as processes will get throttled
if the pfmemalloc reserves get depleted but performance will not degrade
as smoothly.
[mgorman@suse.de: Expanded changelog]
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When a user or administrator requires swap for their application, they
create a swap partition and file, format it with mkswap and activate it
with swapon. Swap over the network is considered as an option in diskless
systems. The two likely scenarios are when blade servers are used as part
of a cluster where the form factor or maintenance costs do not allow the
use of disks and thin clients.
The Linux Terminal Server Project recommends the use of the Network Block
Device (NBD) for swap according to the manual at
https://sourceforge.net/projects/ltsp/files/Docs-Admin-Guide/LTSPManual.pdf/download
There is also documentation and tutorials on how to setup swap over NBD at
places like https://help.ubuntu.com/community/UbuntuLTSP/EnableNBDSWAP The
nbd-client also documents the use of NBD as swap. Despite this, the fact
is that a machine using NBD for swap can deadlock within minutes if swap
is used intensively. This patch series addresses the problem.
The core issue is that network block devices do not use mempools like
normal block devices do. As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need. Some years ago, Peter Zijlstra developed a series of
patches that supported swap over an NFS that at least one distribution is
carrying within their kernels. This patch series borrows very heavily
from Peter's work to support swapping over NBD as a pre-requisite to
supporting swap-over-NFS. The bulk of the complexity is concerned with
preserving memory that is allocated from the PFMEMALLOC reserves for use
by the network layer which is needed for both NBD and NFS.
Patch 1 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
preserve access to pages allocated under low memory situations
to callers that are freeing memory.
Patch 2 optimises the SLUB fast path to avoid pfmemalloc checks
Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
reserves without setting PFMEMALLOC.
Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
for later use by network packet processing.
Patch 5 only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required
Patch 6 ignores memory policies when ALLOC_NO_WATERMARKS is set.
Patches 7-12 allows network processing to use PFMEMALLOC reserves when
the socket has been marked as being used by the VM to clean pages. If
packets are received and stored in pages that were allocated under
low-memory situations and are unrelated to the VM, the packets
are dropped.
Patch 11 reintroduces __skb_alloc_page which the networking
folk may object to but is needed in some cases to propogate
pfmemalloc from a newly allocated page to an skb. If there is a
strong objection, this patch can be dropped with the impact being
that swap-over-network will be slower in some cases but it should
not fail.
Patch 13 is a micro-optimisation to avoid a function call in the
common case.
Patch 14 tags NBD sockets as being SOCK_MEMALLOC so they can use
PFMEMALLOC if necessary.
Patch 15 notes that it is still possible for the PFMEMALLOC reserve
to be depleted. To prevent this, direct reclaimers get throttled on
a waitqueue if 50% of the PFMEMALLOC reserves are depleted. It is
expected that kswapd and the direct reclaimers already running
will clean enough pages for the low watermark to be reached and
the throttled processes are woken up.
Patch 16 adds a statistic to track how often processes get throttled
Some basic performance testing was run using kernel builds, netperf on
loopback for UDP and TCP, hackbench (pipes and sockets), iozone and
sysbench. Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant performance
variances.
For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD. 8*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop. The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure.
Without the patches and using SLUB, the machine locks up within minutes
and runs to completion with them applied. With SLAB, the story is
different as an unpatched kernel run to completion. However, the patched
kernel completed the test 45% faster.
MICRO
3.5.0-rc2 3.5.0-rc2
vanilla swapnbd
Unrecognised test vmscan-anon-mmap-write
MMTests Statistics: duration
Sys Time Running Test (seconds) 197.80 173.07
User+Sys Time Running Test (seconds) 206.96 182.03
Total Elapsed Time (seconds) 3240.70 1762.09
This patch: mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
Allocations of pages below the min watermark run a risk of the machine
hanging due to a lack of memory. To prevent this, only callers who have
PF_MEMALLOC or TIF_MEMDIE set and are not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated to
a slab though, nothing prevents other callers consuming free objects
within those slabs. This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.
When this patch is applied, pages allocated from below the low watermark
are returned with page->pfmemalloc set and it is up to the caller to
determine how the page should be protected. SLAB restricts access to any
page with page->pfmemalloc set to callers which are known to able to
access the PFMEMALLOC reserve. If one is not available, an attempt is
made to allocate a new page rather than use a reserve. SLUB is a bit more
relaxed in that it only records if the current per-CPU page was allocated
from PFMEMALLOC reserve and uses another partial slab if the caller does
not have the necessary GFP or process flags. This was found to be
sufficient in tests to avoid hangs due to SLUB generally maintaining
smaller lists than SLAB.
In low-memory conditions it does mean that !PFMEMALLOC allocators can fail
a slab allocation even though free objects are available because they are
being preserved for callers that are freeing pages.
[a.p.zijlstra@chello.nl: Original implementation]
[sebastian@breakpoint.cc: Correct order of page flag clearing]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kmemcheck_alloc_shadow() requires irqs to be enabled, so wait to disable
them until after its called for __GFP_WAIT allocations.
This fixes a warning for such allocations:
WARNING: at kernel/lockdep.c:2739 lockdep_trace_alloc+0x14e/0x1c0()
Acked-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Move the mutex handling into the common kmem_cache_create()
function.
Then we can also move more checks out of SLAB's kmem_cache_create()
into the common code.
Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Use the mutex definition from SLAB and make it the common way to take a sleeping lock.
This has the effect of using a mutex instead of a rw semaphore for SLUB.
SLOB gains the use of a mutex for kmem_cache_create serialization.
Not needed now but SLOB may acquire some more features later (like slabinfo
/ sysfs support) through the expansion of the common code that will
need this.
Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
All allocators have some sort of support for the bootstrap status.
Setup a common definition for the boot states and make all slab
allocators use that definition.
Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Kmem_cache_create() does a variety of sanity checks but those
vary depending on the allocator. Use the strictest tests and put them into
a slab_common file. Make the tests conditional on CONFIG_DEBUG_VM.
This patch has the effect of adding sanity checks for SLUB and SLOB
under CONFIG_DEBUG_VM and removes the checks in SLAB for !CONFIG_DEBUG_VM.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
If list_for_each_entry, etc complete a traversal of the list, the iterator
variable ends up pointing to an address at an offset from the list head,
and not a meaningful structure. Thus this value should not be used after
the end of the iterator. The patch replaces s->name by al->name, which is
referenced nearby.
This problem was found using Coccinelle (http://coccinelle.lip6.fr/).
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Current implementation of unfreeze_partials() is so complicated,
but benefit from it is insignificant. In addition many code in
do {} while loop have a bad influence to a fail rate of cmpxchg_double_slab.
Under current implementation which test status of cpu partial slab
and acquire list_lock in do {} while loop,
we don't need to acquire a list_lock and gain a little benefit
when front of the cpu partial slab is to be discarded, but this is a rare case.
In case that add_partial is performed and cmpxchg_double_slab is failed,
remove_partial should be called case by case.
I think that these are disadvantages of current implementation,
so I do refactoring unfreeze_partials().
Minimizing code in do {} while loop introduce a reduced fail rate
of cmpxchg_double_slab. Below is output of 'slabinfo -r kmalloc-256'
when './perf stat -r 33 hackbench 50 process 4000 > /dev/null' is done.
** before **
Cmpxchg_double Looping
------------------------
Locked Cmpxchg Double redos 182685
Unlocked Cmpxchg Double redos 0
** after **
Cmpxchg_double Looping
------------------------
Locked Cmpxchg Double redos 177995
Unlocked Cmpxchg Double redos 1
We can see cmpxchg_double_slab fail rate is improved slightly.
Bolow is output of './perf stat -r 30 hackbench 50 process 4000 > /dev/null'.
** before **
Performance counter stats for './hackbench 50 process 4000' (30 runs):
108517.190463 task-clock # 7.926 CPUs utilized ( +- 0.24% )
2,919,550 context-switches # 0.027 M/sec ( +- 3.07% )
100,774 CPU-migrations # 0.929 K/sec ( +- 4.72% )
124,201 page-faults # 0.001 M/sec ( +- 0.15% )
401,500,234,387 cycles # 3.700 GHz ( +- 0.24% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
250,576,913,354 instructions # 0.62 insns per cycle ( +- 0.13% )
45,934,956,860 branches # 423.297 M/sec ( +- 0.14% )
188,219,787 branch-misses # 0.41% of all branches ( +- 0.56% )
13.691837307 seconds time elapsed ( +- 0.24% )
** after **
Performance counter stats for './hackbench 50 process 4000' (30 runs):
107784.479767 task-clock # 7.928 CPUs utilized ( +- 0.22% )
2,834,781 context-switches # 0.026 M/sec ( +- 2.33% )
93,083 CPU-migrations # 0.864 K/sec ( +- 3.45% )
123,967 page-faults # 0.001 M/sec ( +- 0.15% )
398,781,421,836 cycles # 3.700 GHz ( +- 0.22% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
250,189,160,419 instructions # 0.63 insns per cycle ( +- 0.09% )
45,855,370,128 branches # 425.436 M/sec ( +- 0.10% )
169,881,248 branch-misses # 0.37% of all branches ( +- 0.43% )
13.596272341 seconds time elapsed ( +- 0.22% )
No regression is found, but rather we can see slightly better result.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
get_freelist(), unfreeze_partials() are only called with interrupt disabled,
so __cmpxchg_double_slab() is suitable.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
slab_node() could access current->mempolicy from interrupt context.
However there's a race condition during exit where the mempolicy
is first freed and then the pointer zeroed.
Using this from interrupts seems bogus anyways. The interrupt
will interrupt a random process and therefore get a random
mempolicy. Many times, this will be idle's, which noone can change.
Just disable this here and always use local for slab
from interrupts. I also cleaned up the callers of slab_node a bit
which always passed the same argument.
I believe the original mempolicy code did that in fact,
so it's likely a regression.
v2: send version with correct logic
v3: simplify. fix typo.
Reported-by: Arun Sharma <asharma@fb.com>
Cc: penberg@kernel.org
Cc: cl@linux.com
Signed-off-by: Andi Kleen <ak@linux.intel.com>
[tdmackey@twitter.com: Rework control flow based on feedback from
cl@linux.com, fix logic, and cleanup current task_struct reference]
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: David Mackey <tdmackey@twitter.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Define a struct that describes common fields used in all slab allocators.
A slab allocator either uses the common definition (like SLOB) or is
required to provide members of kmem_cache with the definition given.
After that it will be possible to share code that
only operates on those fields of kmem_cache.
The patch basically takes the slob definition of kmem cache and
uses the field namees for the other allocators.
It also standardizes the names used for basic object lengths in
allocators:
object_size Struct size specified at kmem_cache_create. Basically
the payload expected to be used by the subsystem.
size The size of memory allocator for each object. This size
is larger than object_size and includes padding, alignment
and extra metadata for each object (f.e. for debugging
and rcu).
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
* Fix a merge conflict in mm/slub.c::acquire_slab() due to commit 02d7633
("slub: fix a memory leak in get_partial_node()").
Conflicts:
mm/slub.c
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Pull slab updates from Pekka Enberg:
"Mainly a bunch of SLUB fixes from Joonsoo Kim"
* 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux:
slub: use __SetPageSlab function to set PG_slab flag
slub: fix a memory leak in get_partial_node()
slub: remove unused argument of init_kmem_cache_node()
slub: fix a possible memory leak
Documentations: Fix slabinfo.c directory in vm/slub.txt
slub: fix incorrect return type of get_any_partial()
Avoid passing the kmem_cache_cpu pointer to node_match. This makes the
node_match function more generic and easier to understand.
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Store the value of c->page to avoid additional fetches
from per cpu data.
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Processing on fields of kmem_cache_cpu is cleaner if code working on fields
of this struct is taken out of deactivate_slab().
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The node field is always page_to_nid(c->page). So its rather easy to
replace. Note that there maybe slightly more overhead in various hot paths
due to the need to shift the bits from page->flags. However, that is mostly
compensated for by a smaller footprint of the kmem_cache_cpu structure (this
patch reduces that to 3 words per cache) which allows better caching.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Moving the attempt to get a slab page from the partial lists simplifies
__slab_alloc which is rather complicated.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Avoid the loop in acquire slab and simply fail if there is a conflict.
This will cause the next page on the list to be considered.
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Verify that objects returned from __slab_alloc come from slab pages
in the correct state.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The variable "object" really refers to a list of objects that we
are handling.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
To set page-flag, using SetPageXXXX() and __SetPageXXXX() is more
understandable and maintainable. So change it.
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
In the case which is below,
1. acquire slab for cpu partial list
2. free object to it by remote cpu
3. page->freelist = t
then memory leak is occurred.
Change acquire_slab() not to zap freelist when it works for cpu partial list.
I think it is a sufficient solution for fixing a memory leak.
Below is output of 'slabinfo -r kmalloc-256'
when './perf stat -r 30 hackbench 50 process 4000 > /dev/null' is done.
***Vanilla***
Sizes (bytes) Slabs Debug Memory
------------------------------------------------------------------------
Object : 256 Total : 468 Sanity Checks : Off Total: 3833856
SlabObj: 256 Full : 111 Redzoning : Off Used : 2004992
SlabSiz: 8192 Partial: 302 Poisoning : Off Loss : 1828864
Loss : 0 CpuSlab: 55 Tracking : Off Lalig: 0
Align : 8 Objects: 32 Tracing : Off Lpadd: 0
***Patched***
Sizes (bytes) Slabs Debug Memory
------------------------------------------------------------------------
Object : 256 Total : 300 Sanity Checks : Off Total: 2457600
SlabObj: 256 Full : 204 Redzoning : Off Used : 2348800
SlabSiz: 8192 Partial: 33 Poisoning : Off Loss : 108800
Loss : 0 CpuSlab: 63 Tracking : Off Lalig: 0
Align : 8 Objects: 32 Tracing : Off Lpadd: 0
Total and loss number is the impact of this patch.
Cc: <stable@vger.kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
I found some kernel messages such as:
SLUB raid5-md127: kmem_cache_destroy called for cache that still has objects.
Pid: 6143, comm: mdadm Tainted: G O 3.4.0-rc6+ #75
Call Trace:
kmem_cache_destroy+0x328/0x400
free_conf+0x2d/0xf0 [raid456]
stop+0x41/0x60 [raid456]
md_stop+0x1a/0x60 [md_mod]
do_md_stop+0x74/0x470 [md_mod]
md_ioctl+0xff/0x11f0 [md_mod]
blkdev_ioctl+0xd8/0x7a0
block_ioctl+0x3b/0x40
do_vfs_ioctl+0x96/0x560
sys_ioctl+0x91/0xa0
system_call_fastpath+0x16/0x1b
Then using kmemleak I found these messages:
unreferenced object 0xffff8800b6db7380 (size 112):
comm "mdadm", pid 5783, jiffies 4294810749 (age 90.589s)
hex dump (first 32 bytes):
01 01 db b6 ad 4e ad de ff ff ff ff ff ff ff ff .....N..........
ff ff ff ff ff ff ff ff 98 40 4a 82 ff ff ff ff .........@J.....
backtrace:
kmemleak_alloc+0x21/0x50
kmem_cache_alloc+0xeb/0x1b0
kmem_cache_open+0x2f1/0x430
kmem_cache_create+0x158/0x320
setup_conf+0x649/0x770 [raid456]
run+0x68b/0x840 [raid456]
md_run+0x529/0x940 [md_mod]
do_md_run+0x18/0xc0 [md_mod]
md_ioctl+0xba8/0x11f0 [md_mod]
blkdev_ioctl+0xd8/0x7a0
block_ioctl+0x3b/0x40
do_vfs_ioctl+0x96/0x560
sys_ioctl+0x91/0xa0
system_call_fastpath+0x16/0x1b
This bug was introduced by commit a8364d5555 ("slub: only IPI CPUs that
have per cpu obj to flush"), which did not include checks for per cpu
partial pages being present on a cpu.
Signed-off-by: majianpeng <majianpeng@gmail.com>
Cc: Gilad Ben-Yossef <gilad@benyossef.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Tested-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We don't use the argument since commit 3b89d7d881
('slub: move min_partial to struct kmem_cache'), so remove it
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Memory allocated by kstrdup should be freed,
when kmalloc(kmem_size, GFP_KERNEL) is failed.
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Commit 497b66f2ec ('slub: return object pointer
from get_partial() / new_slab().') changed return type of some functions.
This updates missing part.
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Merge third batch of patches from Andrew Morton:
- Some MM stragglers
- core SMP library cleanups (on_each_cpu_mask)
- Some IPI optimisations
- kexec
- kdump
- IPMI
- the radix-tree iterator work
- various other misc bits.
"That'll do for -rc1. I still have ~10 patches for 3.4, will send
those along when they've baked a little more."
* emailed from Andrew Morton <akpm@linux-foundation.org>: (35 commits)
backlight: fix typo in tosa_lcd.c
crc32: add help text for the algorithm select option
mm: move hugepage test examples to tools/testing/selftests/vm
mm: move slabinfo.c to tools/vm
mm: move page-types.c from Documentation to tools/vm
selftests/Makefile: make `run_tests' depend on `all'
selftests: launch individual selftests from the main Makefile
radix-tree: use iterators in find_get_pages* functions
radix-tree: rewrite gang lookup using iterator
radix-tree: introduce bit-optimized iterator
fs/proc/namespaces.c: prevent crash when ns_entries[] is empty
nbd: rename the nbd_device variable from lo to nbd
pidns: add reboot_pid_ns() to handle the reboot syscall
sysctl: use bitmap library functions
ipmi: use locks on watchdog timeout set on reboot
ipmi: simplify locking
ipmi: fix message handling during panics
ipmi: use a tasklet for handling received messages
ipmi: increase KCS timeouts
ipmi: decrease the IPMI message transaction time in interrupt mode
...
flush_all() is called for each kmem_cache_destroy(). So every cache being
destroyed dynamically ends up sending an IPI to each CPU in the system,
regardless if the cache has ever been used there.
For example, if you close the Infinband ipath driver char device file, the
close file ops calls kmem_cache_destroy(). So running some infiniband
config tool on one a single CPU dedicated to system tasks might interrupt
the rest of the 127 CPUs dedicated to some CPU intensive or latency
sensitive task.
I suspect there is a good chance that every line in the output of "git
grep kmem_cache_destroy linux/ | grep '\->'" has a similar scenario.
This patch attempts to rectify this issue by sending an IPI to flush the
per cpu objects back to the free lists only to CPUs that seem to have such
objects.
The check which CPU to IPI is racy but we don't care since asking a CPU
without per cpu objects to flush does no damage and as far as I can tell
the flush_all by itself is racy against allocs on remote CPUs anyway, so
if you required the flush_all to be determinstic, you had to arrange for
locking regardless.
Without this patch the following artificial test case:
$ cd /sys/kernel/slab
$ for DIR in *; do cat $DIR/alloc_calls > /dev/null; done
produces 166 IPIs on an cpuset isolated CPU. With it it produces none.
The code path of memory allocation failure for CPUMASK_OFFSTACK=y
config was tested using fault injection framework.
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Avi Kivity <avi@redhat.com>
Cc: Michal Nazarewicz <mina86@mina86.org>
Cc: Kosaki Motohiro <kosaki.motohiro@gmail.com>
Cc: Milton Miller <miltonm@bga.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull SLAB changes from Pekka Enberg:
"There's the new kmalloc_array() API, minor fixes and performance
improvements, but quite honestly, nothing terribly exciting."
* 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux:
mm: SLAB Out-of-memory diagnostics
slab: introduce kmalloc_array()
slub: per cpu partial statistics change
slub: include include for prefetch
slub: Do not hold slub_lock when calling sysfs_slab_add()
slub: prefetch next freelist pointer in slab_alloc()
slab, cleanup: remove unneeded return
Commit c0ff7453bb ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") wins a super prize for the largest number of
memory barriers entered into fast paths for one commit.
[get|put]_mems_allowed is incredibly heavy with pairs of full memory
barriers inserted into a number of hot paths. This was detected while
investigating at large page allocator slowdown introduced some time
after 2.6.32. The largest portion of this overhead was shown by
oprofile to be at an mfence introduced by this commit into the page
allocator hot path.
For extra style points, the commit introduced the use of yield() in an
implementation of what looks like a spinning mutex.
This patch replaces the full memory barriers on both read and write
sides with a sequence counter with just read barriers on the fast path
side. This is much cheaper on some architectures, including x86. The
main bulk of the patch is the retry logic if the nodemask changes in a
manner that can cause a false failure.
While updating the nodemask, a check is made to see if a false failure
is a risk. If it is, the sequence number gets bumped and parallel
allocators will briefly stall while the nodemask update takes place.
In a page fault test microbenchmark, oprofile samples from
__alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The
actual results were
3.3.0-rc3 3.3.0-rc3
rc3-vanilla nobarrier-v2r1
Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%)
Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%)
Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%)
Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%)
Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%)
Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%)
Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%)
Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%)
Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%)
Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%)
Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%)
Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%)
Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%)
Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%)
Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 135.68 132.17
User+Sys Time Running Test (seconds) 164.2 160.13
Total Elapsed Time (seconds) 123.46 120.87
The overall improvement is small but the System CPU time is much
improved and roughly in correlation to what oprofile reported (these
performance figures are without profiling so skew is expected). The
actual number of page faults is noticeably improved.
For benchmarks like kernel builds, the overall benefit is marginal but
the system CPU time is slightly reduced.
To test the actual bug the commit fixed I opened two terminals. The
first ran within a cpuset and continually ran a small program that
faulted 100M of anonymous data. In a second window, the nodemask of the
cpuset was continually randomised in a loop.
Without the commit, the program would fail every so often (usually
within 10 seconds) and obviously with the commit everything worked fine.
With this patch applied, it also worked fine so the fix should be
functionally equivalent.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch split the cpu_partial_free into 2 parts: cpu_partial_node, PCP refilling
times from node partial; and same name cpu_partial_free, PCP refilling times in
slab_free slow path. A new statistic 'cpu_partial_drain' is added to get PCP
drain to node partial times. These info are useful when do PCP tunning.
The slabinfo.c code is unchanged, since cpu_partial_node is not on slow path.
Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Otherwise m68k breaks:
On Mon, 30 Jan 2012, Geert Uytterhoeven wrote:
> m68k/allmodconfig at http://kisskb.ellerman.id.au/kisskb/buildresult/5527349/
>
> mm/slub.c:274: error: implicit declaration of function 'prefetch'
>
> Sorry, didn't notice it earlier due to other build breakage in -next.
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
sysfs_slab_add() calls various sysfs functions that actually may
end up in userspace doing all sorts of things.
Release the slub_lock after adding the kmem_cache structure to the list.
At that point the address of the kmem_cache is not known so we are
guaranteed exlusive access to the following modifications to the
kmem_cache structure.
If the sysfs_slab_add fails then reacquire the slub_lock to
remove the kmem_cache structure from the list.
Cc: <stable@vger.kernel.org> # 3.3+
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Move CMPXCHG_DOUBLE and rename it to HAVE_CMPXCHG_DOUBLE so architectures
can simply select the option if it is supported.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While implementing cmpxchg_double() on s390 I realized that we don't set
CONFIG_CMPXCHG_LOCAL despite the fact that we have support for it.
However setting that option will increase the size of struct page by
eight bytes on 64 bit, which we certainly do not want. Also, it doesn't
make sense that a present cpu feature should increase the size of struct
page.
Besides that it looks like the dependency to CMPXCHG_LOCAL is wrong and
that it should depend on CMPXCHG_DOUBLE instead.
This patch:
If an architecture supports CMPXCHG_LOCAL this shouldn't result
automatically in larger struct pages if the SLUB allocator is used.
Instead introduce a new config option "HAVE_ALIGNED_STRUCT_PAGE" which
can be selected if a double word aligned struct page is required. Also
update x86 Kconfig so that it should work as before.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux:
slub: disallow changing cpu_partial from userspace for debug caches
slub: add missed accounting
slub: Extract get_freelist from __slab_alloc
slub: Switch per cpu partial page support off for debugging
slub: fix a possible memleak in __slab_alloc()
slub: fix slub_max_order Documentation
slub: add missed accounting
slab: add taint flag outputting to debug paths.
slub: add taint flag outputting to debug paths
slab: introduce slab_max_order kernel parameter
slab: rename slab_break_gfp_order to slab_max_order
Disable slub debug facilities and allocate slabs at minimal order when
debug_guardpage_minorder > 0 to increase probability to catch random
memory corruption by cpu exception.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For caches with debugging enabled, "slub: Switch per cpu partial page
support off for debugging" changes cpu_partial to 0. It shouldn't be
tunable from userspace for such caches, otherwise the same accounting
issues arise during validation.
This patch disallows tuning /sys/kernel/slab/cache/cpu_partial to be non-
zero for caches with debugging enabled.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
* 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: Remove irqsafe_cpu_xxx variants
Fix up conflict in arch/x86/include/asm/percpu.h due to clash with
cebef5beed ("x86: Fix and improve percpu_cmpxchg{8,16}b_double()")
which edited the (now removed) irqsafe_cpu_cmpxchg*_double code.
Just like the per-CPU ones they had several
problems/shortcomings:
Only the first memory operand was mentioned in the asm()
operands, and the 2x64-bit version didn't have a memory clobber
while the 2x32-bit one did. The former allowed the compiler to
not recognize the need to re-load the data in case it had it
cached in some register, while the latter was overly
destructive.
The types of the local copies of the old and new values were
incorrect (the types of the pointed-to variables should be used
here, to make sure the respective old/new variable types are
compatible).
The __dummy/__junk variables were pointless, given that local
copies of the inputs already existed (and can hence be used for
discarded outputs).
The 32-bit variant of cmpxchg_double_local() referenced
cmpxchg16b_local().
At once also:
- change the return value type to what it really is: 'bool'
- unify 32- and 64-bit variants
- abstract out the common part of the 'normal' and 'local' variants
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/4F01F12A020000780006A19B@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We simply say that regular this_cpu use must be safe regardless of
preemption and interrupt state. That has no material change for x86
and s390 implementations of this_cpu operations. However, arches that
do not provide their own implementation for this_cpu operations will
now get code generated that disables interrupts instead of preemption.
-tj: This is part of on-going percpu API cleanup. For detailed
discussion of the subject, please refer to the following thread.
http://thread.gmane.org/gmane.linux.kernel/1222078
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <alpine.DEB.2.00.1112221154380.11787@router.home>
With per-cpu partial list, slab is added to partial list first and then moved
to node list. The __slab_free() code path for add/remove_partial is almost
deprecated(except for slub debug). But we forget to account add/remove_partial
when move per-cpu partial pages to node list, so the statistics for such events
are always 0. Add corresponding accounting.
This is against the patch "slub: use correct parameter to add a page to
partial list tail"
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
get_freelist retrieves free objects from the page freelist (put there by remote
frees) or deactivates a slab page if no more objects are available.
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Eric saw an issue with accounting of slabs during validation. Its not
possible to determine accurately how many per cpu partial slabs exist at
any time so this switches off per cpu partial pages during debug.
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Zhihua Che reported a possible memleak in slub allocator on
CONFIG_PREEMPT=y builds.
It is possible current thread migrates right before disabling irqs in
__slab_alloc(). We must check again c->freelist, and perform a normal
allocation instead of scratching c->freelist.
Many thanks to Zhihua Che for spotting this bug, introduced in 2.6.39
V2: Its also possible an IRQ freed one (or several) object(s) and
populated c->freelist, so its not a CONFIG_PREEMPT only problem.
Cc: <stable@vger.kernel.org> [2.6.39+]
Reported-by: Zhihua Che <zhihua.che@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
With per-cpu partial list, slab is added to partial list first and then moved
to node list. The __slab_free() code path for add/remove_partial is almost
deprecated(except for slub debug). But we forget to account add/remove_partial
when move per-cpu partial pages to node list, so the statistics for such events
are always 0. Add corresponding accounting.
This is against the patch "slub: use correct parameter to add a page to
partial list tail"
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
show_slab_objects() can trigger NULL dereferences or memory corruption.
Another cpu can change its c->page to NULL or c->node to NUMA_NO_NODE
while we use them.
Use ACCESS_ONCE(c->page) and ACCESS_ONCE(c->node) to make sure this
cannot happen.
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The cmpxchg must be irq safe. The fallback for this_cpu_cmpxchg only
disables preemption which results in per cpu partial page operation
potentially failing on non x86 platforms.
This patch fixes the following problem reported by Christian Kujau:
I seem to hit it with heavy disk & cpu IO is in progress on this
PowerBook
G4. Full dmesg & .config: http://nerdbynature.de/bits/3.2.0-rc1/oops/
I've enabled some debug options and now it really points to slub.c:2166
http://nerdbynature.de/bits/3.2.0-rc1/oops/oops4m.jpg
With debug options enabled I'm currently in the xmon debugger, not sure
what to make of it yet, I'll try to get something useful out of it :)
Reported-by: Christian Kujau <lists@nerdbynature.de>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
When we get corruption reports, it's useful to see if the kernel was
tainted, to rule out problems we can't do anything about.
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Lockdep reports there is potential deadlock for slub node list_lock.
discard_slab() is called with the lock hold in unfreeze_partials(),
which could trigger a slab allocation, which could hold the lock again.
discard_slab() doesn't need hold the lock actually, if the slab is
already removed from partial list.
Acked-by: Christoph Lameter <cl@linux.com>
Reported-and-tested-by: Yong Zhang <yong.zhang0@gmail.com>
Reported-and-tested-by: Julie Sullivan <kernelmail.jms@gmail.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
unfreeze_partials() needs add the page to partial list tail, since such page
hasn't too many free objects. We now explictly use DEACTIVATE_TO_TAIL for this,
while DEACTIVATE_TO_TAIL != 1. This will cause performance regression (eg, more
lock contention in node->list_lock) without below fix.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
memchr_inv() is mainly used to check whether the whole buffer is filled
with just a specified byte.
The function name and prototype are stolen from logfs and the
implementation is from SLUB.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: Joern Engel <joern@logfs.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Discarding slab should be done when node partial > min_partial. Otherwise,
node partial slab may eat up all memory.
Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Correct comment errors, that mistake cpu partial objects number as pages
number, may make reader misunderstand.
Signed-off-by: Alex Shi <alex.shi@intel.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Historically /proc/slabinfo and files under /sys/kernel/slab/* have
world read permissions and are accessible to the world. slabinfo
contains rather private information related both to the kernel and
userspace tasks. Depending on the situation, it might reveal either
private information per se or information useful to make another
targeted attack. Some examples of what can be learned by
reading/watching for /proc/slabinfo entries:
1) dentry (and different *inode*) number might reveal other processes fs
activity. The number of dentry "active objects" doesn't strictly show
file count opened/touched by a process, however, there is a good
correlation between them. The patch "proc: force dcache drop on
unauthorized access" relies on the privacy of dentry count.
2) different inode entries might reveal the same information as (1), but
these are more fine granted counters. If a filesystem is mounted in a
private mount point (or even a private namespace) and fs type differs from
other mounted fs types, fs activity in this mount point/namespace is
revealed. If there is a single ecryptfs mount point, the whole fs
activity of a single user is revealed. Number of files in ecryptfs
mount point is a private information per se.
3) fuse_* reveals number of files / fs activity of a user in a user
private mount point. It is approx. the same severity as ecryptfs
infoleak in (2).
4) sysfs_dir_cache similar to (2) reveals devices' addition/removal,
which can be otherwise hidden by "chmod 0700 /sys/". With 0444 slabinfo
the precise number of sysfs files is known to the world.
5) buffer_head might reveal some kernel activity. With other
information leaks an attacker might identify what specific kernel
routines generate buffer_head activity.
6) *kmalloc* infoleaks are very situational. Attacker should watch for
the specific kmalloc size entry and filter the noise related to the unrelated
kernel activity. If an attacker has relatively silent victim system, he
might get rather precise counters.
Additional information sources might significantly increase the slabinfo
infoleak benefits. E.g. if an attacker knows that the processes
activity on the system is very low (only core daemons like syslog and
cron), he may run setxid binaries / trigger local daemon activity /
trigger network services activity / await sporadic cron jobs activity
/ etc. and get rather precise counters for fs and network activity of
these privileged tasks, which is unknown otherwise.
Also hiding slabinfo and /sys/kernel/slab/* is a one step to complicate
exploitation of kernel heap overflows (and possibly, other bugs). The
related discussion:
http://thread.gmane.org/gmane.linux.kernel/1108378
To keep compatibility with old permission model where non-root
monitoring daemon could watch for kernel memleaks though slabinfo one
should do:
groupadd slabinfo
usermod -a -G slabinfo $MONITOR_USER
And add the following commands to init scripts (to mountall.conf in
Ubuntu's upstart case):
chmod g+r /proc/slabinfo /sys/kernel/slab/*/*
chgrp slabinfo /proc/slabinfo /sys/kernel/slab/*/*
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Reviewed-by: Kees Cook <kees@ubuntu.com>
Reviewed-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: David Rientjes <rientjes@google.com>
CC: Valdis.Kletnieks@vt.edu
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Alan Cox <alan@linux.intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
I find a way to reduce a variable in get_partial_node(). That is also helpful
for code understanding.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Adding slab to partial list head/tail is sensitive to performance.
So explicitly uses DEACTIVATE_TO_TAIL/DEACTIVATE_TO_HEAD to document
it to avoid we get it wrong.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Shaohua Li <shli@kernel.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The slab has just one free object, adding it to partial list head doesn't make
sense. And it can cause lock contentation. For example,
1. CPU takes the slab from partial list
2. fetch an object
3. switch to another slab
4. free an object, then the slab is added to partial list again
In this way n->list_lock will be heavily contended.
In fact, Alex had a hackbench regression. 3.1-rc1 performance drops about 70%
against 3.0. This patch fixes it.
Acked-by: Christoph Lameter <cl@linux.com>
Reported-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Shaohua Li <shli@kernel.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Allow filling out the rest of the kmem_cache_cpu cacheline with pointers to
partial pages. The partial page list is used in slab_free() to avoid
per node lock taking.
In __slab_alloc() we can then take multiple partial pages off the per
node partial list in one go reducing node lock pressure.
We can also use the per cpu partial list in slab_alloc() to avoid scanning
partial lists for pages with free objects.
The main effect of a per cpu partial list is that the per node list_lock
is taken for batches of partial pages instead of individual ones.
Potential future enhancements:
1. The pickup from the partial list could be perhaps be done without disabling
interrupts with some work. The free path already puts the page into the
per cpu partial list without disabling interrupts.
2. __slab_free() may have some code paths that could use optimization.
Performance:
Before After
./hackbench 100 process 200000
Time: 1953.047 1564.614
./hackbench 100 process 20000
Time: 207.176 156.940
./hackbench 100 process 20000
Time: 204.468 156.940
./hackbench 100 process 20000
Time: 204.879 158.772
./hackbench 10 process 20000
Time: 20.153 15.853
./hackbench 10 process 20000
Time: 20.153 15.986
./hackbench 10 process 20000
Time: 19.363 16.111
./hackbench 1 process 20000
Time: 2.518 2.307
./hackbench 1 process 20000
Time: 2.258 2.339
./hackbench 1 process 20000
Time: 2.864 2.163
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
There is no need anymore to return the pointer to a slab page from get_partial()
since the page reference can be stored in the kmem_cache_cpu structures "page" field.
Return an object pointer instead.
That in turn allows a simplification of the spaghetti code in __slab_alloc().
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Pass the kmem_cache_cpu pointer to get_partial(). That way
we can avoid the this_cpu_write() statements.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
inuse will always be set to page->objects. There is no point in
initializing the field to zero in new_slab() and then overwriting
the value in __slab_alloc().
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Two statements in __slab_alloc() do not have any effect.
1. c->page is already set to NULL by deactivate_slab() called right before.
2. gfpflags are masked in new_slab() before being passed to the page
allocator. There is no need to mask gfpflags in __slab_alloc in particular
since most frequent processing in __slab_alloc does not require the use of a
gfpmask.
Cc: torvalds@linux-foundation.org
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
There are two situations in which slub holds a lock while releasing
pages:
A. During kmem_cache_shrink()
B. During kmem_cache_close()
For A build a list while holding the lock and then release the pages
later. In case of B we are the last remaining user of the slab so
there is no need to take the listlock.
After this patch all calls to the page allocator to free pages are
done without holding any spinlocks. kmem_cache_destroy() will still
hold the slub_lock semaphore.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
deactivate_slab() has the comparison if more than the minimum number of
partial pages are in the partial list wrong. An effect of this may be that
empty pages are not freed from deactivate_slab(). The result could be an
OOM due to growth of the partial slabs per node. Frees mostly occur from
__slab_free which is okay so this would only affect use cases where a lot
of switching around of per cpu slabs occur.
Switching per cpu slabs occurs with high frequency if debugging options are
enabled.
Reported-and-tested-by: Xiaotian Feng <xtfeng@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The check_bytes() function is used by slub debugging. It returns a pointer
to the first unmatching byte for a character in the given memory area.
If the character for matching byte is greater than 0x80, check_bytes()
doesn't work. Becuase 64-bit pattern is generated as below.
value64 = value | value << 8 | value << 16 | value << 24;
value64 = value64 | value64 << 32;
The integer promotions are performed and sign-extended as the type of value
is u8. The upper 32 bits of value64 is 0xffffffff in the first line, and
the second line has no effect.
This fixes the 64-bit pattern generation.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Matt Mackall <mpm@selenic.com>
Reviewed-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
* 'slub/lockless' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6: (21 commits)
slub: When allocating a new slab also prep the first object
slub: disable interrupts in cmpxchg_double_slab when falling back to pagelock
Avoid duplicate _count variables in page_struct
Revert "SLUB: Fix build breakage in linux/mm_types.h"
SLUB: Fix build breakage in linux/mm_types.h
slub: slabinfo update for cmpxchg handling
slub: Not necessary to check for empty slab on load_freelist
slub: fast release on full slab
slub: Add statistics for the case that the current slab does not match the node
slub: Get rid of the another_slab label
slub: Avoid disabling interrupts in free slowpath
slub: Disable interrupts in free_debug processing
slub: Invert locking and avoid slab lock
slub: Rework allocator fastpaths
slub: Pass kmem_cache struct to lock and freeze slab
slub: explicit list_lock taking
slub: Add cmpxchg_double_slab()
mm: Rearrange struct page
slub: Move page->frozen handling near where the page->freelist handling occurs
slub: Do not use frozen page flag but a bit in the page counters
...
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (43 commits)
fs: Merge split strings
treewide: fix potentially dangerous trailing ';' in #defined values/expressions
uwb: Fix misspelling of neighbourhood in comment
net, netfilter: Remove redundant goto in ebt_ulog_packet
trivial: don't touch files that are removed in the staging tree
lib/vsprintf: replace link to Draft by final RFC number
doc: Kconfig: `to be' -> `be'
doc: Kconfig: Typo: square -> squared
doc: Konfig: Documentation/power/{pm => apm-acpi}.txt
drivers/net: static should be at beginning of declaration
drivers/media: static should be at beginning of declaration
drivers/i2c: static should be at beginning of declaration
XTENSA: static should be at beginning of declaration
SH: static should be at beginning of declaration
MIPS: static should be at beginning of declaration
ARM: static should be at beginning of declaration
rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check
Update my e-mail address
PCIe ASPM: forcedly -> forcibly
gma500: push through device driver tree
...
Fix up trivial conflicts:
- arch/arm/mach-ep93xx/dma-m2p.c (deleted)
- drivers/gpio/gpio-ep93xx.c (renamed and context nearby)
- drivers/net/r8169.c (just context changes)
We need to branch to the debug code for the first object if we allocate
a new slab otherwise the first object will be marked wrongly as inactive.
Tested-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
All these are instances of
#define NAME value;
or
#define NAME(params_opt) value;
These of course fail to build when used in contexts like
if(foo $OP NAME)
while(bar $OP NAME)
and may silently generate the wrong code in contexts such as
foo = NAME + 1; /* foo = value; + 1; */
bar = NAME - 1; /* bar = value; - 1; */
baz = NAME & quux; /* baz = value; & quux; */
Reported on comp.lang.c,
Message-ID: <ab0d55fe-25e5-482b-811e-c475aa6065c3@c29g2000yqd.googlegroups.com>
Initial analysis of the dangers provided by Keith Thompson in that thread.
There are many more instances of more complicated macros having unnecessary
trailing semicolons, but this pile seems to be all of the cases of simple
values suffering from the problem. (Thus things that are likely to be found
in one of the contexts above, more complicated ones aren't.)
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Split cmpxchg_double_slab into two functions. One for the case where we know that
interrupts are disabled (and therefore the fallback does not need to disable
interrupts) and one for the other cases where fallback will also disable interrupts.
This fixes the issue that __slab_free called cmpxchg_double_slab in some scenarios
without disabling interrupts.
Tested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This fixes the following build breakage commit d6543e3 ("slub: Enable backtrace
for create/delete points"):
CC mm/slub.o
mm/slub.c: In function ‘set_track’:
mm/slub.c:428: error: storage size of ‘trace’ isn’t known
mm/slub.c:435: error: implicit declaration of function ‘save_stack_trace’
mm/slub.c:428: warning: unused variable ‘trace’
make[1]: *** [mm/slub.o] Error 1
make: *** [mm/slub.o] Error 2
Signed-off-by: Pekka Enberg <penberg@kernel.org>
slub checks for poison one byte by one, which is highly inefficient
and shows up frequently as a highest cpu-eater in perf top.
Joining reads gives nice speedup:
(Compiling some project with different options)
make -j12 make clean
slub_debug disabled: 1m 27s 1.2 s
slub_debug enabled: 1m 46s 7.6 s
slub_debug enabled + this patch: 1m 33s 3.2 s
check_bytes still shows up high, but not always at the top.
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: linux-mm@kvack.org
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This is for tracking down suspect memory usage.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
load_freelist is now only branched to only if there are objects available.
So no need to check the object variable for NULL.
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Make deactivation occur implicitly while checking out the current freelist.
This avoids one cmpxchg operation on a slab that is now fully in use.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Slub reloads the per cpu slab if the page does not satisfy the NUMA condition. Track
those reloads since doing so has a performance impact.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
We can avoid deactivate slab in special cases if we do the
deactivation of slabs in each code flow that leads to new_slab.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Disabling interrupts can be avoided now. However, list operation still require
disabling interrupts since allocations can occur from interrupt
contexts and there is no way to perform atomic list operations.
The acquition of the list_lock therefore has to disable interrupts as well.
Dropping interrupt handling significantly simplifies the slowpath.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
We will be calling free_debug_processing with interrupts disabled
in some case when the later patches are applied. Some of the
functions called by free_debug_processing expect interrupts to be
off.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Locking slabs is no longer necesary if the arch supports cmpxchg operations
and if no debuggin features are used on a slab. If the arch does not support
cmpxchg then we fallback to use the slab lock to do a cmpxchg like operation.
The patch also changes the lock order. Slab locks are subsumed to the node lock
now. With that approach slab_trylocking is no longer necessary.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Rework the allocation paths so that updates of the page freelist, frozen state
and number of objects use cmpxchg_double_slab().
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
We need more information about the slab for the cmpxchg implementation.
Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The allocator fastpath rework does change the usage of the list_lock.
Remove the list_lock processing from the functions that hide them from the
critical sections and move them into those critical sections.
This in turn simplifies the support functions (no __ variant needed anymore)
and simplifies the lock handling on bootstrap.
Inline add_partial since it becomes pretty simple.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Add a function that operates on the second doubleword in the page struct
and manipulates the object counters, the freelist and the frozen attribute.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This is necessary because the frozen bit has to be handled in the same cmpxchg_double
with the freelist and the counters.
Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Do not use a page flag for the frozen bit. It needs to be part
of the state that is handled with cmpxchg_double(). So use a bit
in the counter struct in the page struct for that purpose.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Do the irq handling in allocate_slab() instead of __slab_alloc().
__slab_alloc() is already cluttered and allocate_slab() is already
fiddling around with gfp flags.
v6->v7:
Only increment ORDER_FALLBACK if we get a page during fallback
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
On an architecture without CMPXCHG_LOCAL but with DEBUG_VM enabled,
the VM_BUG_ON() in __pcpu_double_call_return_bool() will cause an early
panic during boot unless we always align cpu_slab properly.
In principle we could remove the alignment-testing VM_BUG_ON() for
architectures that don't have CMPXCHG_LOCAL, but leaving it in means
that new code will tend not to break x86 even if it is introduced
on another platform, and it's low cost to require alignment.
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Commit a71ae47a2c ("slub: Fix double bit unlock in debug mode")
removed the only goto to this label, resulting in
mm/slub.c: In function '__slab_alloc':
mm/slub.c:1834: warning: label 'unlock_out' defined but not used
fixed trivially by the removal of the label itself too.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 442b06bcea ("slub: Remove node check in slab_free") added a
call to deactivate_slab() in the debug case in __slab_alloc(), which
unlocks the current slab used for allocation. Going to the label
'unlock_out' then does it again.
Also, in the debug case we do not need all the other processing that the
'unlock_out' path does. We always fall back to the slow path in the
debug case. So the tid update is useless.
Similarly, ALLOC_SLOWPATH would just be incremented for all allocations.
Also a pretty useless thing.
So simply restore irq flags and return the object.
Signed-off-by: Christoph Lameter <cl@linux.com>
Reported-and-bisected-by: James Morris <jmorris@namei.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
Reported-by: Jens Axboe <jaxboe@fusionio.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can set the page pointing in the percpu structure to
NULL to have the same effect as setting c->node to NUMA_NO_NODE.
Gets rid of one check in slab_free() that was only used for
forcing the slab_free to the slowpath for debugging.
We still need to set c->node to NUMA_NO_NODE to force the
slab_alloc() fastpath to the slowpath in case of debugging.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Jumping to a label inside a conditional is considered poor style,
especially considering the current organization of __slab_alloc().
This removes the 'load_from_page' label and just duplicates the three
lines of code that it uses:
c->node = page_to_nid(page);
c->page = page;
goto load_freelist;
since it's probably not worth making this a separate helper function.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Fastpath can do a speculative access to a page that CONFIG_DEBUG_PAGE_ALLOC may have
marked as invalid to retrieve the pointer to the next free object.
Use probe_kernel_read in that case in order not to cause a page fault.
Cc: <stable@kernel.org> # 38.x
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Move the #ifdef so that get_map is only defined if CONFIG_SLUB_DEBUG is defined.
Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Remove the #ifdefs. This means that the irqsafe_cpu_cmpxchg_double() is used
everywhere.
There may be performance implications since:
A. We now have to manage a transaction ID for all arches
B. The interrupt holdoff for arches not supporting CONFIG_CMPXCHG_LOCAL is reduced
to a very short irqoff section.
There are no multiple irqoff/irqon sequences as a result of this change. Even in the fallback
case we only have to do one disable and enable like before.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The SLUB allocator use of the cmpxchg_double logic was wrong: it
actually needs the irq-safe one.
That happens automatically when we use the native unlocked 'cmpxchg8b'
instruction, but when compiling the kernel for older x86 CPUs that do
not support that instruction, we fall back to the generic emulation
code.
And if you don't specify that you want the irq-safe version, the generic
code ends up just open-coding the cmpxchg8b equivalent without any
protection against interrupts or preemption. Which definitely doesn't
work for SLUB.
This was reported by Werner Landgraf <w.landgraf@ru.ru>, who saw
instability with his distro-kernel that was compiled to support pretty
much everything under the sun. Most big Linux distributions tend to
compile for PPro and later, and would never have noticed this problem.
This also fixes the prototypes for the irqsafe cmpxchg_double functions
to use 'bool' like they should.
[ Btw, that whole "generic code defaults to no protection" design just
sounds stupid - if the code needs no protection, there is no reason to
use "cmpxchg_double" to begin with. So we should probably just remove
the unprotected version entirely as pointless. - Linus ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reported-and-tested-by: werner <w.landgraf@ru.ru>
Acked-and-tested-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1105041539050.3005@ionos
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Its easier to read if its with the check for debugging flags.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
If the node does not change then there is no need to recalculate
the node from the page struct. So move the node determination
into the places where we acquire a new slab page.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
__slab_alloc is full of "c->page" repeats. Lets just use one local variable
named "page" for this. Also avoids the need to a have another variable
called "new".
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The bit map of free objects in a slab page is determined in various functions
if debugging is enabled.
Provide a common function for that purpose.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
There's no config named SLAB_DEBUG, and it should be a typo
of SLUB_DEBUG.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
It turns out that the cmpxchg16b emulation has to access vmalloced
percpu memory with interrupts disabled. If the memory has never
been touched before then the fault necessary to establish the
mapping will not to occur and the kernel will fail on boot.
Fix that by reusing the CONFIG_PREEMPT code that writes the
cpu number into a field on every cpu. Writing to the per cpu
area before causes the mapping to be established before we get
to a cmpxchg16b emulation.
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
On Thu, 24 Mar 2011, Ingo Molnar wrote:
> RIP: 0010:[<ffffffff810570a9>] [<ffffffff810570a9>] get_next_timer_interrupt+0x119/0x260
That's a typical timer crash, but you were unable to debug it with
debugobjects because commit d3f661d6 broke those.
Cc: Christoph Lameter <cl@linux.com>
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
OOM path is missing the irq restore in the CONFIG_CMPXCHG_LOCAL case.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The redo label needs #ifdeffery. Fixes the following problem introduced by
commit 8a5ec0ba42 ("Lockless (and preemptless) fastpaths for slub"):
mm/slub.c: In function 'slab_free':
mm/slub.c:2124: warning: label 'redo' defined but not used
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The size of struct rcu_head may be changed. When it becomes larger,
it will pollute the page array.
We reserve some some bytes for struct rcu_head when a slab
is allocated in this situation.
Changed from V1:
use VM_BUG_ON instead BUG_ON
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
There is no "struct" for slub's slab, it shares with struct page.
But struct page is very small, it is insufficient when we need
to add some metadata for slab.
So we add a field "reserved" to struct kmem_cache, when a slab
is allocated, kmem_cache->reserved bytes are automatically reserved
at the end of the slab for slab's metadata.
Changed from v1:
Export the reserved field via sysfs
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Use the this_cpu_cmpxchg_double functionality to implement a lockless
allocation algorithm on arches that support fast this_cpu_ops.
Each of the per cpu pointers is paired with a transaction id that ensures
that updates of the per cpu information can only occur in sequence on
a certain cpu.
A transaction id is a "long" integer that is comprised of an event number
and the cpu number. The event number is incremented for every change to the
per cpu state. This means that the cmpxchg instruction can verify for an
update that nothing interfered and that we are updating the percpu structure
for the processor where we picked up the information and that we are also
currently on that processor when we update the information.
This results in a significant decrease of the overhead in the fastpaths. It
also makes it easy to adopt the fast path for realtime kernels since this
is lockless and does not require the use of the current per cpu area
over the critical section. It is only important that the per cpu area is
current at the beginning of the critical section and at the end.
So there is no need even to disable preemption.
Test results show that the fastpath cycle count is reduced by up to ~ 40%
(alloc/free test goes from ~140 cycles down to ~80). The slowpath for kfree
adds a few cycles.
Sadly this does nothing for the slowpath which is where the main issues with
performance in slub are but the best case performance rises significantly.
(For that see the more complex slub patches that require cmpxchg_double)
Kmalloc: alloc/free test
Before:
10000 times kmalloc(8)/kfree -> 134 cycles
10000 times kmalloc(16)/kfree -> 152 cycles
10000 times kmalloc(32)/kfree -> 144 cycles
10000 times kmalloc(64)/kfree -> 142 cycles
10000 times kmalloc(128)/kfree -> 142 cycles
10000 times kmalloc(256)/kfree -> 132 cycles
10000 times kmalloc(512)/kfree -> 132 cycles
10000 times kmalloc(1024)/kfree -> 135 cycles
10000 times kmalloc(2048)/kfree -> 135 cycles
10000 times kmalloc(4096)/kfree -> 135 cycles
10000 times kmalloc(8192)/kfree -> 144 cycles
10000 times kmalloc(16384)/kfree -> 754 cycles
After:
10000 times kmalloc(8)/kfree -> 78 cycles
10000 times kmalloc(16)/kfree -> 78 cycles
10000 times kmalloc(32)/kfree -> 82 cycles
10000 times kmalloc(64)/kfree -> 88 cycles
10000 times kmalloc(128)/kfree -> 79 cycles
10000 times kmalloc(256)/kfree -> 79 cycles
10000 times kmalloc(512)/kfree -> 85 cycles
10000 times kmalloc(1024)/kfree -> 82 cycles
10000 times kmalloc(2048)/kfree -> 82 cycles
10000 times kmalloc(4096)/kfree -> 85 cycles
10000 times kmalloc(8192)/kfree -> 82 cycles
10000 times kmalloc(16384)/kfree -> 706 cycles
Kmalloc: Repeatedly allocate then free test
Before:
10000 times kmalloc(8) -> 211 cycles kfree -> 113 cycles
10000 times kmalloc(16) -> 174 cycles kfree -> 115 cycles
10000 times kmalloc(32) -> 235 cycles kfree -> 129 cycles
10000 times kmalloc(64) -> 222 cycles kfree -> 120 cycles
10000 times kmalloc(128) -> 343 cycles kfree -> 139 cycles
10000 times kmalloc(256) -> 827 cycles kfree -> 147 cycles
10000 times kmalloc(512) -> 1048 cycles kfree -> 272 cycles
10000 times kmalloc(1024) -> 2043 cycles kfree -> 528 cycles
10000 times kmalloc(2048) -> 4002 cycles kfree -> 571 cycles
10000 times kmalloc(4096) -> 7740 cycles kfree -> 628 cycles
10000 times kmalloc(8192) -> 8062 cycles kfree -> 850 cycles
10000 times kmalloc(16384) -> 8895 cycles kfree -> 1249 cycles
After:
10000 times kmalloc(8) -> 190 cycles kfree -> 129 cycles
10000 times kmalloc(16) -> 76 cycles kfree -> 123 cycles
10000 times kmalloc(32) -> 126 cycles kfree -> 124 cycles
10000 times kmalloc(64) -> 181 cycles kfree -> 128 cycles
10000 times kmalloc(128) -> 310 cycles kfree -> 140 cycles
10000 times kmalloc(256) -> 809 cycles kfree -> 165 cycles
10000 times kmalloc(512) -> 1005 cycles kfree -> 269 cycles
10000 times kmalloc(1024) -> 1999 cycles kfree -> 527 cycles
10000 times kmalloc(2048) -> 3967 cycles kfree -> 570 cycles
10000 times kmalloc(4096) -> 7658 cycles kfree -> 637 cycles
10000 times kmalloc(8192) -> 8111 cycles kfree -> 859 cycles
10000 times kmalloc(16384) -> 8791 cycles kfree -> 1173 cycles
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The following patch will make the fastpaths lockless and will no longer
require interrupts to be disabled. Calling the free hook with irq disabled
will no longer be possible.
Move the slab_free_hook_irq() logic into slab_free_hook. Only disable
interrupts if the features are selected that require callbacks with
interrupts off and reenable after calls have been made.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/slub.c: In function 'ksize':
mm/slub.c:2728: error: implicit declaration of function 'slab_ksize'
slab_ksize() needs to go out of CONFIG_SLUB_DEBUG section.
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Mariusz Kozlowski <mk@lab.zgora.pl>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Recent use of ksize() in network stack (commit ca44ac38 : net: don't
reallocate skb->head unless the current one hasn't the needed extra size
or is shared) triggers kmemcheck warnings, because ksize() can return
more space than kmemcheck is aware of.
Pekka Enberg noticed SLAB+kmemcheck is doing the right thing, while SLUB
+kmemcheck doesnt.
Bugzilla reference #27212
Reported-by: Christian Casteyde <casteyde.christian@free.fr>
Suggested-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: Changli Gao <xiaosuo@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The last user was ext4 and Eric Sandeen removed the call in a recent patch. See
the following URL for the discussion:
http://marc.info/?l=linux-ext4&m=129546975702198&w=2
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The purpose of the locking is to prevent removal and additions
of nodes when statistics are gathered for a slab cache. So we
need to avoid racing with memory hotplug functionality.
It is enough to take the memory hotplug locks there instead
of the slub_lock.
online_pages() currently does not acquire the memory_hotplug
lock. Another patch will be submitted by the memory hotplug
authors to take the memory hotplug lock and describe the
uses of the memory hotplug lock to protect against
adding and removal of nodes from non hotplug data structures.
Cc: <stable@kernel.org> # 2.6.37
Reported-and-tested-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6:
slub: Fix a crash during slabinfo -v
tracing/slab: Move kmalloc tracepoint out of inline code
slub: Fix slub_lock down/up imbalance
slub: Fix build breakage in Documentation/vm
slub tracing: move trace calls out of always inlined functions to reduce kernel code size
slub: move slabinfo.c to tools/slub/slabinfo.c
Commit f7cb193362 ("SLUB: Pass active
and inactive redzone flags instead of boolean to debug functions")
missed two instances of check_object(). This caused a lot of warnings
during 'slabinfo -v' finally leading to a crash:
BUG ext4_xattr: Freepointer corrupt
...
BUG buffer_head: Freepointer corrupt
...
BUG ext4_alloc_context: Freepointer corrupt
...
...
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: [<ffffffff810a291f>] file_sb_list_del+0x1c/0x35
PGD 79d78067 PUD 79e67067 PMD 0
Oops: 0002 [#1] SMP
last sysfs file: /sys/kernel/slab/:t-0000192/validate
This patch fixes the problem by converting the two missed instances.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tero Roponen <tero.roponen@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Commit f7cb193362 ("SLUB: Pass active
and inactive redzone flags instead of boolean to debug functions")
missed two instances of check_object(). This caused a lot of warnings
during 'slabinfo -v' finally leading to a crash:
BUG ext4_xattr: Freepointer corrupt
...
BUG buffer_head: Freepointer corrupt
...
BUG ext4_alloc_context: Freepointer corrupt
...
...
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: [<ffffffff810a291f>] file_sb_list_del+0x1c/0x35
PGD 79d78067 PUD 79e67067 PMD 0
Oops: 0002 [#1] SMP
last sysfs file: /sys/kernel/slab/:t-0000192/validate
This patch fixes the problem by converting the two missed instances.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tero Roponen <tero.roponen@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
There are two places, that do not release the slub_lock.
Respective bugs were introduced by sysfs changes ab4d5ed5 (slub: Enable
sysfs support for !CONFIG_SLUB_DEBUG) and 2bce6485 ( slub: Allow removal
of slab caches during boot).
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
There are two places, that do not release the slub_lock.
Respective bugs were introduced by sysfs changes ab4d5ed5 (slub: Enable
sysfs support for !CONFIG_SLUB_DEBUG) and 2bce6485 ( slub: Allow removal
of slab caches during boot).
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Having the trace calls defined in the always inlined kmalloc functions
in include/linux/slub_def.h causes a lot of code duplication as the
trace functions get instantiated for each kamalloc call site. This can
simply be removed by pushing the trace calls down into the functions in
slub.c.
On my x86_64 built this patch shrinks the code size of the kernel by
approx 36K and also shrinks the code size of many modules -- too many to
list here ;)
size vmlinux (2.6.36) reports
text data bss dec hex filename
5410611 743172 828928 6982711 6a8c37 vmlinux
5373738 744244 828928 6946910 6a005e vmlinux + patch
The resulting kernel has had some testing & kmalloc trace still seems to
work.
This patch
- moves trace_kmalloc out of the inlined kmalloc() and pushes it down
into kmem_cache_alloc_trace() so this it only get instantiated once.
- rename kmem_cache_alloc_notrace() to kmem_cache_alloc_trace() to
indicate that now is does have tracing. (maybe this would better being
called something like kmalloc_kmem_cache ?)
- adds a new function kmalloc_order() to handle allocation and tracing
of large allocations of page order.
- removes tracing from the inlined kmalloc_large() replacing them with a
call to kmalloc_order();
- move tracing out of inlined kmalloc_node() and pushing it down into
kmem_cache_alloc_node_trace
- rename kmem_cache_alloc_node_notrace() to
kmem_cache_alloc_node_trace()
- removes the include of trace/events/kmem.h from slub_def.h.
v2
- keep kmalloc_order_trace inline when !CONFIG_TRACE
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This patch fixes the following build breakage when memory hotplug is enabled on
UMA configurations:
/home/test/linux-2.6/mm/slub.c: In function 'kmem_cache_init':
/home/test/linux-2.6/mm/slub.c:3031:2: error: 'slab_memory_callback'
undeclared (first use in this function)
/home/test/linux-2.6/mm/slub.c:3031:2: note: each undeclared
identifier is reported only once for each function it appears in
make[2]: *** [mm/slub.o] Error 1
make[1]: *** [mm] Error 2
make: *** [sub-make] Error 2
Reported-by: Zimny Lech <napohybelskurwysynom2010@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
There is a lot of #ifdef/#endifs that can be avoided if functions would be in different
places. Move them around and reduce #ifdef.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Currently disabling CONFIG_SLUB_DEBUG also disabled SYSFS support meaning
that the slabs cannot be tuned without DEBUG.
Make SYSFS support independent of CONFIG_SLUB_DEBUG
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This patch optimizes slab_free() debug check to use "c->node != NUMA_NO_NODE"
instead of "c->node >= 0" because the former generates smaller code on x86-64:
Before:
4736: 48 39 70 08 cmp %rsi,0x8(%rax)
473a: 75 26 jne 4762 <kfree+0xa2>
473c: 44 8b 48 10 mov 0x10(%rax),%r9d
4740: 45 85 c9 test %r9d,%r9d
4743: 78 1d js 4762 <kfree+0xa2>
After:
4736: 48 39 70 08 cmp %rsi,0x8(%rax)
473a: 75 23 jne 475f <kfree+0x9f>
473c: 83 78 10 ff cmpl $0xffffffffffffffff,0x10(%rax)
4740: 74 1d je 475f <kfree+0x9f>
This patch also cleans up __slab_alloc() to use NUMA_NO_NODE instead of "-1"
for enabling debugging for a per-CPU cache.
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Christoph Lameter
