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commit cc9a6c8776615f9c194ccf0b63a0aa5628235545 upstream.
Stable note: Not tracked in Bugzilla. [get|put]_mems_allowed() is extremely
expensive and severely impacted page allocator performance. This
is part of a series of patches that reduce page allocator overhead.
Commit c0ff7453bb5c ("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>
Signed-off-by: Mel Gorman <mgorman@suse.de>
[bwh: Forward-ported from 3.0 to 3.2: apply the upstream changes
to get_any_partial()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 02d7633fa567be7bf55a993b79d2a31b95ce2227 upstream.
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.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 66c4c35c6bc5a1a452b024cf0364635b28fd94e4 upstream.
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.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 73736e0387ba0e6d2b703407b4d26168d31516a7 upstream.
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.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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When a slab is freed by __slab_free() and the slab can only contain a
single object ever then it was full (and therefore not on the partial
lists but on the full list in the debug case) before we reached
slab_empty.
This caused the following full list corruption when SLUB debugging was enabled:
[ 5913.233035] ------------[ cut here ]------------
[ 5913.233097] WARNING: at lib/list_debug.c:53 __list_del_entry+0x8d/0x98()
[ 5913.233101] Hardware name: Adamo 13
[ 5913.233105] list_del corruption. prev->next should be ffffea000434fd20, but was ffffea0004199520
[ 5913.233108] Modules linked in: nfs fscache fuse ebtable_nat ebtables ppdev parport_pc lp parport ipt_MASQUERADE iptable_nat nf_nat nfsd lockd nfs_acl auth_rpcgss xt_CHECKSUM sunrpc iptable_mangle bridge stp llc cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables rfcomm bnep arc4 iwlagn snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_intel btusb mac80211 snd_hda_codec bluetooth snd_hwdep snd_seq snd_seq_device snd_pcm usb_debug dell_wmi sparse_keymap cdc_ether usbnet cdc_acm uvcvideo cdc_wdm mii cfg80211 snd_timer dell_laptop videodev dcdbas snd microcode v4l2_compat_ioctl32 soundcore joydev tg3 pcspkr snd_page_alloc iTCO_wdt i2c_i801 rfkill iTCO_vendor_support wmi virtio_net kvm_intel kvm ipv6 xts gf128mul dm_crypt i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 5913.233213] Pid: 0, comm: swapper Not tainted 3.0.0+ #127
[ 5913.233213] Call Trace:
[ 5913.233213] <IRQ> [<ffffffff8105df18>] warn_slowpath_common+0x83/0x9b
[ 5913.233213] [<ffffffff8105dfd3>] warn_slowpath_fmt+0x46/0x48
[ 5913.233213] [<ffffffff8127e7c1>] __list_del_entry+0x8d/0x98
[ 5913.233213] [<ffffffff8127e7da>] list_del+0xe/0x2d
[ 5913.233213] [<ffffffff814e0430>] __slab_free+0x1db/0x235
[ 5913.233213] [<ffffffff811706ab>] ? bvec_free_bs+0x35/0x37
[ 5913.233213] [<ffffffff811706ab>] ? bvec_free_bs+0x35/0x37
[ 5913.233213] [<ffffffff811706ab>] ? bvec_free_bs+0x35/0x37
[ 5913.233213] [<ffffffff81133085>] kmem_cache_free+0x88/0x102
[ 5913.233213] [<ffffffff811706ab>] bvec_free_bs+0x35/0x37
[ 5913.233213] [<ffffffff811706e1>] bio_free+0x34/0x64
[ 5913.233213] [<ffffffff813dc390>] dm_bio_destructor+0x12/0x14
[ 5913.233213] [<ffffffff8116fef6>] bio_put+0x2b/0x2d
[ 5913.233213] [<ffffffff813dccab>] clone_endio+0x9e/0xb4
[ 5913.233213] [<ffffffff8116f7dd>] bio_endio+0x2d/0x2f
[ 5913.233213] [<ffffffffa00148da>] crypt_dec_pending+0x5c/0x8b [dm_crypt]
[ 5913.233213] [<ffffffffa00150a9>] crypt_endio+0x78/0x81 [dm_crypt]
[ Full discussion here: https://lkml.org/lkml/2011/8/4/375 ]
Make sure that we remove such a slab also from the full lists.
Reported-and-tested-by: Dave Jones <davej@redhat.com>
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>
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Less code and same functionality. The output would be:
| Object c7428000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
| Object c7428010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
| Object c7428020: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
| Object c7428030: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkk.
| Redzone c742803c: bb bb bb bb ....
| Padding c7428064: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ
| Padding c7428074: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZ
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6
* '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
...
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git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
* '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)
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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>
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git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6
* 'slab-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6:
slab: fix DEBUG_SLAB warning
slab: shrink sizeof(struct kmem_cache)
slab: fix DEBUG_SLAB build
SLUB: Fix missing <linux/stacktrace.h> include
slub: reduce overhead of slub_debug
slub: Add method to verify memory is not freed
slub: Enable backtrace for create/delete points
slab allocators: Provide generic description of alignment defines
slab, slub, slob: Unify alignment definition
slob/lockdep: Fix gfp flags passed to lockdep
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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>
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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>
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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>
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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>
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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>
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This patch attempts to grab a backtrace for the creation
and deletion points of the slub object. When a fault is
detected, we can then get a better idea of where the item
was deleted.
Example output from debugging some funky nfs/rpc behaviour:
=============================================================================
BUG kmalloc-64: Object is on free-list
-----------------------------------------------------------------------------
INFO: Allocated in rpcb_getport_async+0x39c/0x5a5 [sunrpc] age=381 cpu=3 pid=3750
__slab_alloc+0x348/0x3ba
kmem_cache_alloc_trace+0x67/0xe7
rpcb_getport_async+0x39c/0x5a5 [sunrpc]
call_bind+0x70/0x75 [sunrpc]
__rpc_execute+0x78/0x24b [sunrpc]
rpc_execute+0x3d/0x42 [sunrpc]
rpc_run_task+0x79/0x81 [sunrpc]
rpc_call_sync+0x3f/0x60 [sunrpc]
rpc_ping+0x42/0x58 [sunrpc]
rpc_create+0x4aa/0x527 [sunrpc]
nfs_create_rpc_client+0xb1/0xf6 [nfs]
nfs_init_client+0x3b/0x7d [nfs]
nfs_get_client+0x453/0x5ab [nfs]
nfs_create_server+0x10b/0x437 [nfs]
nfs_fs_mount+0x4ca/0x708 [nfs]
mount_fs+0x6b/0x152
INFO: Freed in rpcb_map_release+0x3f/0x44 [sunrpc] age=30 cpu=2 pid=29049
__slab_free+0x57/0x150
kfree+0x107/0x13a
rpcb_map_release+0x3f/0x44 [sunrpc]
rpc_release_calldata+0x12/0x14 [sunrpc]
rpc_free_task+0x59/0x61 [sunrpc]
rpc_final_put_task+0x82/0x8a [sunrpc]
__rpc_execute+0x23c/0x24b [sunrpc]
rpc_async_schedule+0x10/0x12 [sunrpc]
process_one_work+0x230/0x41d
worker_thread+0x133/0x217
kthread+0x7d/0x85
kernel_thread_helper+0x4/0x10
INFO: Slab 0xffffea00029aa470 objects=20 used=9 fp=0xffff8800be7830d8 flags=0x20000000004081
INFO: Object 0xffff8800be7830d8 @offset=4312 fp=0xffff8800be7827a8
Bytes b4 0xffff8800be7830c8: 87 a8 96 00 01 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a .�......ZZZZZZZZ
Object 0xffff8800be7830d8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
Object 0xffff8800be7830e8: 6b 6b 6b 6b 01 08 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkk..kkkkkkkkkk
Object 0xffff8800be7830f8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
Object 0xffff8800be783108: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkkkkkk�
Redzone 0xffff8800be783118: bb bb bb bb bb bb bb bb �������������
Padding 0xffff8800be783258: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ
Pid: 29049, comm: kworker/2:2 Not tainted 3.0.0-rc4+ #8
Call Trace:
[<ffffffff811055c3>] print_trailer+0x131/0x13a
[<ffffffff81105601>] object_err+0x35/0x3e
[<ffffffff8110746f>] verify_mem_not_deleted+0x7a/0xb7
[<ffffffffa02851b5>] rpcb_getport_done+0x23/0x126 [sunrpc]
[<ffffffffa027d0ba>] rpc_exit_task+0x3f/0x6d [sunrpc]
[<ffffffffa027d4ab>] __rpc_execute+0x78/0x24b [sunrpc]
[<ffffffffa027d6c0>] ? rpc_execute+0x42/0x42 [sunrpc]
[<ffffffffa027d6d0>] rpc_async_schedule+0x10/0x12 [sunrpc]
[<ffffffff810611b7>] process_one_work+0x230/0x41d
[<ffffffff81061102>] ? process_one_work+0x17b/0x41d
[<ffffffff81063613>] worker_thread+0x133/0x217
[<ffffffff810634e0>] ? manage_workers+0x191/0x191
[<ffffffff81066e10>] kthread+0x7d/0x85
[<ffffffff81485924>] kernel_thread_helper+0x4/0x10
[<ffffffff8147eb18>] ? retint_restore_args+0x13/0x13
[<ffffffff81066d93>] ? __init_kthread_worker+0x56/0x56
[<ffffffff81485920>] ? gs_change+0x13/0x13
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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