summaryrefslogtreecommitdiffstats
path: root/mm/slub.c
Commit message (Collapse)AuthorAgeFilesLines
* cpuset: mm: reduce large amounts of memory barrier related damage v3Mel Gorman2012-03-211-15/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* mm,x86,um: move CMPXCHG_DOUBLE config optionHeiko Carstens2012-01-121-3/+6
| | | | | | | | | | | | | | 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>
* mm,slub,x86: decouple size of struct page from CONFIG_CMPXCHG_LOCALHeiko Carstens2012-01-121-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Merge branch 'slab/for-linus' of ↵Linus Torvalds2012-01-111-29/+48
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux * '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
| * Merge branch 'slab/urgent' into slab/for-linusPekka Enberg2012-01-111-1/+3
| |\
| | * slub: add missed accountingShaohua Li2011-12-131-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * slub: Switch per cpu partial page support off for debuggingChristoph Lameter2011-12-131-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | slub: disallow changing cpu_partial from userspace for debug cachesDavid Rientjes2012-01-101-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | slub: Extract get_freelist from __slab_allocChristoph Lameter2011-12-131-25/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | slub: fix a possible memleak in __slab_alloc()Eric Dumazet2011-12-131-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | slub: add missed accountingShaohua Li2011-11-271-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | Merge branch 'slab/urgent' into slab/nextPekka Enberg2011-11-271-16/+26
| |\|
| * | slub: add taint flag outputting to debug pathsDave Jones2011-11-161-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | slub: min order when debug_guardpage_minorder > 0Stanislaw Gruszka2012-01-101-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | Merge branch 'for-3.3' of ↵Linus Torvalds2012-01-091-3/+3
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu * '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 cebef5beed3d ("x86: Fix and improve percpu_cmpxchg{8,16}b_double()") which edited the (now removed) irqsafe_cpu_cmpxchg*_double code.
| * | | percpu: Remove irqsafe_cpu_xxx variantsChristoph Lameter2011-12-221-3/+3
| | |/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* / | x86: Fix and improve cmpxchg_double{,_local}()Jan Beulich2012-01-041-2/+2
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | slub: avoid potential NULL dereference or corruptionEric Dumazet2011-11-241-10/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | slub: use irqsafe_cpu_cmpxchg for put_cpu_partialChristoph Lameter2011-11-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | slub: move discard_slab out of node lockShaohua Li2011-11-151-4/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | slub: use correct parameter to add a page to partial list tailShaohua Li2011-11-151-1/+2
|/ | | | | | | | | | | | 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>
* lib/string.c: introduce memchr_inv()Akinobu Mita2011-10-311-45/+2
| | | | | | | | | | | | | | | | | | 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>
*-. Merge branches 'slab/next' and 'slub/partial' into slab/for-linusPekka Enberg2011-10-261-166/+392
|\ \
| | * slub: Discard slab page when node partial > minimum partial numberAlex Shi2011-09-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * slub: correct comments error for per cpu partialAlex Shi2011-09-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * slub: Code optimization in get_partial_node()Alex,Shi2011-09-131-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * slub: per cpu cache for partial pagesChristoph Lameter2011-08-191-47/+292
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * slub: return object pointer from get_partial() / new_slab().Christoph Lameter2011-08-191-60/+73
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * slub: pass kmem_cache_cpu pointer to get_partial()Christoph Lameter2011-08-191-15/+15
| | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * slub: Prepare inuse field in new_slab()Christoph Lameter2011-08-191-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * slub: Remove useless statements in __slab_allocChristoph Lameter2011-08-191-4/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * slub: free slabs without holding locksChristoph Lameter2011-08-191-13/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | mm: restrict access to slab files under procfs and sysfsVasiliy Kulikov2011-09-271-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | Merge branch 'slab/urgent' into slab/nextPekka Enberg2011-09-191-10/+12
| |\ \
| | * | slub: explicitly document position of inserting slab to partial listShaohua Li2011-08-271-6/+6
| |/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | slub: use print_hex_dumpSebastian Andrzej Siewior2011-07-311-35/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | slub: add slab with one free object to partial list tailShaohua Li2011-08-271-1/+1
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | slub: Fix partial count comparison confusionChristoph Lameter2011-08-091-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | slub: fix check_bytes() for slub debuggingAkinobu Mita2011-08-091-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: Fix full list corruption if debugging is onChristoph Lameter2011-08-091-2/+4
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Merge branch 'slub/lockless' of ↵Linus Torvalds2011-07-301-252/+512
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 ...
| * slub: When allocating a new slab also prep the first objectChristoph Lameter2011-07-251-0/+3
| | | | | | | | | | | | | | | | | | 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>
| * slub: disable interrupts in cmpxchg_double_slab when falling back to pagelockChristoph Lameter2011-07-181-4/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * slub: Not necessary to check for empty slab on load_freelistChristoph Lameter2011-07-021-3/+2
| | | | | | | | | | | | | | 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>
| * slub: fast release on full slabChristoph Lameter2011-07-021-2/+19
| | | | | | | | | | | | | | | | | | 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: Add statistics for the case that the current slab does not match the nodeChristoph Lameter2011-07-021-0/+3
| | | | | | | | | | | | | | | | 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>
| * slub: Get rid of the another_slab labelChristoph Lameter2011-07-021-6/+5
| | | | | | | | | | | | | | | | 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>
| * slub: Avoid disabling interrupts in free slowpathChristoph Lameter2011-07-021-11/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * slub: Disable interrupts in free_debug processingChristoph Lameter2011-07-021-4/+10
| | | | | | | | | | | | | | | | | | | | 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>
| * slub: Invert locking and avoid slab lockChristoph Lameter2011-07-021-77/+52
| | | | | | | | | | | | | | | | | | | | | | | | 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>
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-16 14:41:04 +0000