mirror of https://gitee.com/openkylin/linux.git
669 Commits
Author | SHA1 | Message | Date |
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Jesper Dangaard Brouer | 865762a811 |
slab/slub: adjust kmem_cache_alloc_bulk API
Adjust kmem_cache_alloc_bulk API before we have any real users. Adjust API to return type 'int' instead of previously type 'bool'. This is done to allow future extension of the bulk alloc API. A future extension could be to allow SLUB to stop at a page boundary, when specified by a flag, and then return the number of objects. The advantage of this approach, would make it easier to make bulk alloc run without local IRQs disabled. With an approach of cmpxchg "stealing" the entire c->freelist or page->freelist. To avoid overshooting we would stop processing at a slab-page boundary. Else we always end up returning some objects at the cost of another cmpxchg. To keep compatible with future users of this API linking against an older kernel when using the new flag, we need to return the number of allocated objects with this API change. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | 033745189b |
slub: add missing kmem cgroup support to kmem_cache_free_bulk
Initial implementation missed support for kmem cgroup support in kmem_cache_free_bulk() call, add this. If CONFIG_MEMCG_KMEM is not enabled, the compiler should be smart enough to not add any asm code. Incoming bulk free objects can belong to different kmem cgroups, and object free call can happen at a later point outside memcg context. Thus, we need to keep the orig kmem_cache, to correctly verify if a memcg object match against its "root_cache" (s->memcg_params.root_cache). Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | 03ec0ed57f |
slub: fix kmem cgroup bug in kmem_cache_alloc_bulk
The call slab_pre_alloc_hook() interacts with kmemgc and is not allowed to be called several times inside the bulk alloc for loop, due to the call to memcg_kmem_get_cache(). This would result in hitting the VM_BUG_ON in __memcg_kmem_get_cache. As suggested by Vladimir Davydov, change slab_post_alloc_hook() to be able to handle an array of objects. A subtle detail is, loop iterator "i" in slab_post_alloc_hook() must have same type (size_t) as size argument. This helps the compiler to easier realize that it can remove the loop, when all debug statements inside loop evaluates to nothing. Note, this is only an issue because the kernel is compiled with GCC option: -fno-strict-overflow In slab_alloc_node() the compiler inlines and optimizes the invocation of slab_post_alloc_hook(s, flags, 1, &object) by removing the loop and access object directly. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Reported-by: Vladimir Davydov <vdavydov@virtuozzo.com> Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | d0ecd894e3 |
slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the "slowpath" of kmem_cache_free_bulk. The calls slab_free (fastpath) and __slab_free (slowpath) have been extended with support for bulk free, which amortize the overhead of the (locked) cmpxchg_double. To use the new bulking feature, we build what I call a detached freelist. The detached freelist takes advantage of three properties: 1) the free function call owns the object that is about to be freed, thus writing into this memory is synchronization-free. 2) many freelist's can co-exist side-by-side in the same slab-page each with a separate head pointer. 3) it is the visibility of the head pointer that needs synchronization. Given these properties, the brilliant part is that the detached freelist can be constructed without any need for synchronization. The freelist is constructed directly in the page objects, without any synchronization needed. The detached freelist is allocated on the stack of the function call kmem_cache_free_bulk. Thus, the freelist head pointer is not visible to other CPUs. All objects in a SLUB freelist must belong to the same slab-page. Thus, constructing the detached freelist is about matching objects that belong to the same slab-page. The bulk free array is scanned is a progressive manor with a limited look-ahead facility. Kmem debug support is handled in call of slab_free(). Notice kmem_cache_free_bulk no longer need to disable IRQs. This only slowed down single free bulk with approx 3 cycles. Performance data: Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns To get stable and comparable numbers, the kernel have been booted with "slab_merge" (this also improve performance for larger bulk sizes). Performance data, compared against fallback bulking: bulk - fallback bulk - improvement with this patch 1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0% 2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5% 3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6% 4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5% 8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0% 16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3% 30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3% 32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0% 34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0% 48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7% 64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0% 128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0% 158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7% 250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4% Performance data, compared current in-kernel bulking: bulk - curr in-kernel - improvement with this patch 1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5% 2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1% 3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5% 4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1% 8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9% 16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6% 30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0% 32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0% 34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5% 48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0% 64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2% 128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9% 158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0% 250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0% Performance with normal SLUB merging is significantly slower for larger bulking. This is believed to (primarily) be an effect of not having to share the per-CPU data-structures, as tuning per-CPU size can achieve similar performance. bulk - slab_nomerge - normal SLUB merge 1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0 2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0 3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0 4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0 8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0 16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0 30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5 32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4 34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1 48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1 64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28 128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30 158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29 250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19 Joint work with Alexander Duyck. [1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c [akpm@linux-foundation.org: BUG_ON -> WARN_ON;return] Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | 81084651d7 |
slub: support for bulk free with SLUB freelists
Make it possible to free a freelist with several objects by adjusting API of slab_free() and __slab_free() to have head, tail and an objects counter (cnt). Tail being NULL indicate single object free of head object. This allow compiler inline constant propagation in slab_free() and slab_free_freelist_hook() to avoid adding any overhead in case of single object free. This allows a freelist with several objects (all within the same slab-page) to be free'ed using a single locked cmpxchg_double in __slab_free() and with an unlocked cmpxchg_double in slab_free(). Object debugging on the free path is also extended to handle these freelists. When CONFIG_SLUB_DEBUG is enabled it will also detect if objects don't belong to the same slab-page. These changes are needed for the next patch to bulk free the detached freelists it introduces and constructs. Micro benchmarking showed no performance reduction due to this change, when debugging is turned off (compiled with CONFIG_SLUB_DEBUG). Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | b4a6471879 |
slub: mark the dangling ifdef #else of CONFIG_SLUB_DEBUG
The #ifdef of CONFIG_SLUB_DEBUG is located very far from the associated #else. For readability mark it with a comment. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Alexander Duyck <alexander.h.duyck@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Christoph Lameter | 87098373e2 |
slub: avoid irqoff/on in bulk allocation
Use the new function that can do allocation while interrupts are disabled. Avoids irq on/off sequences. Signed-off-by: Christoph Lameter <cl@linux.com> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Alexander Duyck <alexander.h.duyck@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Christoph Lameter | a380a3c755 |
slub: create new ___slab_alloc function that can be called with irqs disabled
Bulk alloc needs a function like that because it enables interrupts before calling __slab_alloc which promptly disables them again using the expensive local_irq_save(). Signed-off-by: Christoph Lameter <cl@linux.com> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Alexander Duyck <alexander.h.duyck@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Kirill A. Shutemov | bc4f610d5a |
slab, slub: use page->rcu_head instead of page->lru plus cast
We have properly typed page->rcu_head, no need to cast page->lru. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman | d0164adc89 |
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
__GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrey Ryabinin | 89d3c87e20 |
mm, slub, kasan: enable user tracking by default with KASAN=y
It's recommended to have slub's user tracking enabled with CONFIG_KASAN, because: a) User tracking disables slab merging which improves detecting out-of-bounds accesses. b) User tracking metadata acts as redzone which also improves detecting out-of-bounds accesses. c) User tracking provides additional information about object. This information helps to understand bugs. Currently it is not enabled by default. Besides recompiling the kernel with KASAN and reinstalling it, user also have to change the boot cmdline, which is not very handy. Enable slub user tracking by default with KASAN=y, since there is no good reason to not do this. [akpm@linux-foundation.org: little fixes, per David] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov | f3ccb2c422 |
memcg: unify slab and other kmem pages charging
We have memcg_kmem_charge and memcg_kmem_uncharge methods for charging and uncharging kmem pages to memcg, but currently they are not used for charging slab pages (i.e. they are only used for charging pages allocated with alloc_kmem_pages). The only reason why the slab subsystem uses special helpers, memcg_charge_slab and memcg_uncharge_slab, is that it needs to charge to the memcg of kmem cache while memcg_charge_kmem charges to the memcg that the current task belongs to. To remove this diversity, this patch adds an extra argument to __memcg_kmem_charge that can be a pointer to a memcg or NULL. If it is not NULL, the function tries to charge to the memcg it points to, otherwise it charge to the current context. Next, it makes the slab subsystem use this function to charge slab pages. Since memcg_charge_kmem and memcg_uncharge_kmem helpers are now used only in __memcg_kmem_charge and __memcg_kmem_uncharge, they are inlined. Since __memcg_kmem_charge stores a pointer to the memcg in the page struct, we don't need memcg_uncharge_slab anymore and can use free_kmem_pages. Besides, one can now detect which memcg a slab page belongs to by reading /proc/kpagecgroup. Note, this patch switches slab to charge-after-alloc design. Since this design is already used for all other memcg charges, it should not make any difference. [hannes@cmpxchg.org: better to have an outer function than a magic parameter for the memcg lookup] Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Wei Yang | 9f835703ea |
mm/slub: calculate start order with reserved in consideration
In slub_order(), the order starts from max(min_order, get_order(min_objects * size)). When (min_objects * size) has different order from (min_objects * size + reserved), it will skip this order via a check in the loop. This patch optimizes this a little by calculating the start order with `reserved' in consideration and removing the check in loop. Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Wei Yang | 033fd1bd3c |
mm/slub: use get_order() instead of fls()
get_order() is more easy to understand. This patch just replaces it. Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Wei Yang | 422ff4d70c |
mm/slub: correct the comment in calculate_order()
In calculate_order(), it tries to calculate the best order by adjusting the fraction and min_objects. On each iteration on min_objects, fraction iterates on 16, 8, 4. Which means the acceptable waste increases with 1/16, 1/8, 1/4. This patch corrects the comment according to the code. Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vlastimil Babka | 96db800f5d |
mm: rename alloc_pages_exact_node() to __alloc_pages_node()
alloc_pages_exact_node() was introduced in commit |
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Joonsoo Kim | 45eb00cd3a |
mm/slub: don't wait for high-order page allocation
Description is almost copied from commit
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Konstantin Khlebnikov | 80da026a8e |
mm/slub: fix slab double-free in case of duplicate sysfs filename
sysfs_slab_add() shouldn't call kobject_put at error path: this puts last reference of kmem-cache kobject and frees it. Kmem cache will be freed second time at error path in kmem_cache_create(). For example this happens when slub debug was enabled in runtime and somebody creates new kmem cache: # echo 1 | tee /sys/kernel/slab/*/sanity_checks # modprobe configfs "configfs_dir_cache" cannot be merged because existing slab have debug and cannot create new slab because unique name ":t-0000096" already taken. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Thomas Gleixner | 588f8ba913 |
mm/slub: move slab initialization into irq enabled region
Initializing a new slab can introduce rather large latencies because most of the initialization runs always with interrupts disabled. There is no point in doing so. The newly allocated slab is not visible yet, so there is no reason to protect it against concurrent alloc/free. Move the expensive parts of the initialization into allocate_slab(), so for all allocations with GFP_WAIT set, interrupts are enabled. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | 3eed034d04 |
slub: add support for kmem_cache_debug in bulk calls
Per request of Joonsoo Kim adding kmem debug support. I've tested that when debugging is disabled, then there is almost no performance impact as this code basically gets removed by the compiler. Need some guidance in enabling and testing this. bulk- PREVIOUS - THIS-PATCH 1 - 43 cycles(tsc) 10.811 ns - 44 cycles(tsc) 11.236 ns improved -2.3% 2 - 27 cycles(tsc) 6.867 ns - 28 cycles(tsc) 7.019 ns improved -3.7% 3 - 21 cycles(tsc) 5.496 ns - 22 cycles(tsc) 5.526 ns improved -4.8% 4 - 24 cycles(tsc) 6.038 ns - 19 cycles(tsc) 4.786 ns improved 20.8% 8 - 17 cycles(tsc) 4.280 ns - 18 cycles(tsc) 4.572 ns improved -5.9% 16 - 17 cycles(tsc) 4.483 ns - 18 cycles(tsc) 4.658 ns improved -5.9% 30 - 18 cycles(tsc) 4.531 ns - 18 cycles(tsc) 4.568 ns improved 0.0% 32 - 58 cycles(tsc) 14.586 ns - 65 cycles(tsc) 16.454 ns improved -12.1% 34 - 53 cycles(tsc) 13.391 ns - 63 cycles(tsc) 15.932 ns improved -18.9% 48 - 65 cycles(tsc) 16.268 ns - 50 cycles(tsc) 12.506 ns improved 23.1% 64 - 53 cycles(tsc) 13.440 ns - 63 cycles(tsc) 15.929 ns improved -18.9% 128 - 79 cycles(tsc) 19.899 ns - 86 cycles(tsc) 21.583 ns improved -8.9% 158 - 90 cycles(tsc) 22.732 ns - 90 cycles(tsc) 22.552 ns improved 0.0% 250 - 95 cycles(tsc) 23.916 ns - 98 cycles(tsc) 24.589 ns improved -3.2% Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | fbd02630c6 |
slub: initial bulk free implementation
This implements SLUB specific kmem_cache_free_bulk(). SLUB allocator now both have bulk alloc and free implemented. Choose to reenable local IRQs while calling slowpath __slab_free(). In worst case, where all objects hit slowpath call, the performance should still be faster than fallback function __kmem_cache_free_bulk(), because local_irq_{disable+enable} is very fast (7-cycles), while the fallback invokes this_cpu_cmpxchg() which is slightly slower (9-cycles). Nitpicking, this should be faster for N>=4, due to the entry cost of local_irq_{disable+enable}. Do notice that the save+restore variant is very expensive, this is key to why this optimization works. CPU: i7-4790K CPU @ 4.00GHz * local_irq_{disable,enable}: 7 cycles(tsc) - 1.821 ns * local_irq_{save,restore} : 37 cycles(tsc) - 9.443 ns Measurements on CPU CPU i7-4790K @ 4.00GHz Baseline normal fastpath (alloc+free cost): 43 cycles(tsc) 10.834 ns Bulk- fallback - this-patch 1 - 58 cycles(tsc) 14.542 ns - 43 cycles(tsc) 10.811 ns improved 25.9% 2 - 50 cycles(tsc) 12.659 ns - 27 cycles(tsc) 6.867 ns improved 46.0% 3 - 48 cycles(tsc) 12.168 ns - 21 cycles(tsc) 5.496 ns improved 56.2% 4 - 47 cycles(tsc) 11.987 ns - 24 cycles(tsc) 6.038 ns improved 48.9% 8 - 46 cycles(tsc) 11.518 ns - 17 cycles(tsc) 4.280 ns improved 63.0% 16 - 45 cycles(tsc) 11.366 ns - 17 cycles(tsc) 4.483 ns improved 62.2% 30 - 45 cycles(tsc) 11.433 ns - 18 cycles(tsc) 4.531 ns improved 60.0% 32 - 75 cycles(tsc) 18.983 ns - 58 cycles(tsc) 14.586 ns improved 22.7% 34 - 71 cycles(tsc) 17.940 ns - 53 cycles(tsc) 13.391 ns improved 25.4% 48 - 80 cycles(tsc) 20.077 ns - 65 cycles(tsc) 16.268 ns improved 18.8% 64 - 71 cycles(tsc) 17.799 ns - 53 cycles(tsc) 13.440 ns improved 25.4% 128 - 91 cycles(tsc) 22.980 ns - 79 cycles(tsc) 19.899 ns improved 13.2% 158 - 100 cycles(tsc) 25.241 ns - 90 cycles(tsc) 22.732 ns improved 10.0% 250 - 102 cycles(tsc) 25.583 ns - 95 cycles(tsc) 23.916 ns improved 6.9% Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | ebe909e0fd |
slub: improve bulk alloc strategy
Call slowpath __slab_alloc() from within the bulk loop, as the side-effect of this call likely repopulates c->freelist. Choose to reenable local IRQs while calling slowpath. Saving some optimizations for later. E.g. it is possible to extract parts of __slab_alloc() and avoid the unnecessary and expensive (37 cycles) local_irq_{save,restore}. For now, be happy calling __slab_alloc() this lower icache impact of this func and I don't have to worry about correctness. Measurements on CPU CPU i7-4790K @ 4.00GHz Baseline normal fastpath (alloc+free cost): 42 cycles(tsc) 10.601 ns Bulk- fallback - this-patch 1 - 58 cycles(tsc) 14.516 ns - 49 cycles(tsc) 12.459 ns improved 15.5% 2 - 51 cycles(tsc) 12.930 ns - 38 cycles(tsc) 9.605 ns improved 25.5% 3 - 49 cycles(tsc) 12.274 ns - 34 cycles(tsc) 8.525 ns improved 30.6% 4 - 48 cycles(tsc) 12.058 ns - 32 cycles(tsc) 8.036 ns improved 33.3% 8 - 46 cycles(tsc) 11.609 ns - 31 cycles(tsc) 7.756 ns improved 32.6% 16 - 45 cycles(tsc) 11.451 ns - 32 cycles(tsc) 8.148 ns improved 28.9% 30 - 79 cycles(tsc) 19.865 ns - 68 cycles(tsc) 17.164 ns improved 13.9% 32 - 76 cycles(tsc) 19.212 ns - 66 cycles(tsc) 16.584 ns improved 13.2% 34 - 74 cycles(tsc) 18.600 ns - 63 cycles(tsc) 15.954 ns improved 14.9% 48 - 88 cycles(tsc) 22.092 ns - 77 cycles(tsc) 19.373 ns improved 12.5% 64 - 80 cycles(tsc) 20.043 ns - 68 cycles(tsc) 17.188 ns improved 15.0% 128 - 99 cycles(tsc) 24.818 ns - 89 cycles(tsc) 22.404 ns improved 10.1% 158 - 99 cycles(tsc) 24.977 ns - 92 cycles(tsc) 23.089 ns improved 7.1% 250 - 106 cycles(tsc) 26.552 ns - 99 cycles(tsc) 24.785 ns improved 6.6% Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | 994eb764ec |
slub bulk alloc: extract objects from the per cpu slab
First piece: acceleration of retrieval of per cpu objects If we are allocating lots of objects then it is advantageous to disable interrupts and avoid the this_cpu_cmpxchg() operation to get these objects faster. Note that we cannot do the fast operation if debugging is enabled, because we would have to add extra code to do all the debugging checks. And it would not be fast anyway. Note also that the requirement of having interrupts disabled avoids having to do processor flag operations. Allocate as many objects as possible in the fast way and then fall back to the generic implementation for the rest of the objects. Measurements on CPU CPU i7-4790K @ 4.00GHz Baseline normal fastpath (alloc+free cost): 42 cycles(tsc) 10.554 ns Bulk- fallback - this-patch 1 - 57 cycles(tsc) 14.432 ns - 48 cycles(tsc) 12.155 ns improved 15.8% 2 - 50 cycles(tsc) 12.746 ns - 37 cycles(tsc) 9.390 ns improved 26.0% 3 - 48 cycles(tsc) 12.180 ns - 33 cycles(tsc) 8.417 ns improved 31.2% 4 - 48 cycles(tsc) 12.015 ns - 32 cycles(tsc) 8.045 ns improved 33.3% 8 - 46 cycles(tsc) 11.526 ns - 30 cycles(tsc) 7.699 ns improved 34.8% 16 - 45 cycles(tsc) 11.418 ns - 32 cycles(tsc) 8.205 ns improved 28.9% 30 - 80 cycles(tsc) 20.246 ns - 73 cycles(tsc) 18.328 ns improved 8.8% 32 - 79 cycles(tsc) 19.946 ns - 72 cycles(tsc) 18.208 ns improved 8.9% 34 - 78 cycles(tsc) 19.659 ns - 71 cycles(tsc) 17.987 ns improved 9.0% 48 - 86 cycles(tsc) 21.516 ns - 82 cycles(tsc) 20.566 ns improved 4.7% 64 - 93 cycles(tsc) 23.423 ns - 89 cycles(tsc) 22.480 ns improved 4.3% 128 - 100 cycles(tsc) 25.170 ns - 99 cycles(tsc) 24.871 ns improved 1.0% 158 - 102 cycles(tsc) 25.549 ns - 101 cycles(tsc) 25.375 ns improved 1.0% 250 - 101 cycles(tsc) 25.344 ns - 100 cycles(tsc) 25.182 ns improved 1.0% Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Christoph Lameter | 484748f0b6 |
slab: infrastructure for bulk object allocation and freeing
Add the basic infrastructure for alloc/free operations on pointer arrays. It includes a generic function in the common slab code that is used in this infrastructure patch to create the unoptimized functionality for slab bulk operations. Allocators can then provide optimized allocation functions for situations in which large numbers of objects are needed. These optimization may avoid taking locks repeatedly and bypass metadata creation if all objects in slab pages can be used to provide the objects required. Allocators can extend the skeletons provided and add their own code to the bulk alloc and free functions. They can keep the generic allocation and freeing and just fall back to those if optimizations would not work (like for example when debugging is on). Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jesper Dangaard Brouer | 2ae44005b6 |
slub: fix spelling succedd to succeed
With this patchset the SLUB allocator now has both bulk alloc and free implemented. This patchset mostly optimizes the "fastpath" where objects are available on the per CPU fastpath page. This mostly amortize the less-heavy none-locked cmpxchg_double used on fastpath. The "fallback" bulking (e.g __kmem_cache_free_bulk) provides a good basis for comparison. Measurements[1] of the fallback functions __kmem_cache_{free,alloc}_bulk have been copied from slab_common.c and forced "noinline" to force a function call like slab_common.c. Measurements on CPU CPU i7-4790K @ 4.00GHz Baseline normal fastpath (alloc+free cost): 42 cycles(tsc) 10.601 ns Measurements last-patch with disabled debugging: Bulk- fallback - this-patch 1 - 57 cycles(tsc) 14.448 ns - 44 cycles(tsc) 11.236 ns improved 22.8% 2 - 51 cycles(tsc) 12.768 ns - 28 cycles(tsc) 7.019 ns improved 45.1% 3 - 48 cycles(tsc) 12.232 ns - 22 cycles(tsc) 5.526 ns improved 54.2% 4 - 48 cycles(tsc) 12.025 ns - 19 cycles(tsc) 4.786 ns improved 60.4% 8 - 46 cycles(tsc) 11.558 ns - 18 cycles(tsc) 4.572 ns improved 60.9% 16 - 45 cycles(tsc) 11.458 ns - 18 cycles(tsc) 4.658 ns improved 60.0% 30 - 45 cycles(tsc) 11.499 ns - 18 cycles(tsc) 4.568 ns improved 60.0% 32 - 79 cycles(tsc) 19.917 ns - 65 cycles(tsc) 16.454 ns improved 17.7% 34 - 78 cycles(tsc) 19.655 ns - 63 cycles(tsc) 15.932 ns improved 19.2% 48 - 68 cycles(tsc) 17.049 ns - 50 cycles(tsc) 12.506 ns improved 26.5% 64 - 80 cycles(tsc) 20.009 ns - 63 cycles(tsc) 15.929 ns improved 21.3% 128 - 94 cycles(tsc) 23.749 ns - 86 cycles(tsc) 21.583 ns improved 8.5% 158 - 97 cycles(tsc) 24.299 ns - 90 cycles(tsc) 22.552 ns improved 7.2% 250 - 102 cycles(tsc) 25.681 ns - 98 cycles(tsc) 24.589 ns improved 3.9% Benchmarking shows impressive improvements in the "fastpath" with a small number of objects in the working set. Once the working set increases, resulting in activating the "slowpath" (that contains the heavier locked cmpxchg_double) the improvement decreases. I'm currently working on also optimizing the "slowpath" (as network stack use-case hits this), but this patchset should provide a good foundation for further improvements. Rest of my patch queue in this area needs some more work, but preliminary results are good. I'm attending Netfilter Workshop[2] next week, and I'll hopefully return working on further improvements in this area. This patch (of 6): s/succedd/succeed/ Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko | 2f064f3485 |
mm: make page pfmemalloc check more robust
Commit |
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Daniel Sanders | 34cc6990d4 |
slab: correct size_index table before replacing the bootstrap kmem_cache_node
This patch moves the initialization of the size_index table slightly earlier so that the first few kmem_cache_node's can be safely allocated when KMALLOC_MIN_SIZE is large. There are currently two ways to generate indices into kmalloc_caches (via kmalloc_index() and via the size_index table in slab_common.c) and on some arches (possibly only MIPS) they potentially disagree with each other until create_kmalloc_caches() has been called. It seems that the intention is that the size_index table is a fast equivalent to kmalloc_index() and that create_kmalloc_caches() patches the table to return the correct value for the cases where kmalloc_index()'s if-statements apply. The failing sequence was: * kmalloc_caches contains NULL elements * kmem_cache_init initialises the element that 'struct kmem_cache_node' will be allocated to. For 32-bit Mips, this is a 56-byte struct and kmalloc_index returns KMALLOC_SHIFT_LOW (7). * init_list is called which calls kmalloc_node to allocate a 'struct kmem_cache_node'. * kmalloc_slab selects the kmem_caches element using size_index[size_index_elem(size)]. For MIPS, size is 56, and the expression returns 6. * This element of kmalloc_caches is NULL and allocation fails. * If it had not already failed, it would have called create_kmalloc_caches() at this point which would have changed size_index[size_index_elem(size)] to 7. I don't believe the bug to be LLVM specific but GCC doesn't normally encounter the problem. I haven't been able to identify exactly what GCC is doing better (probably inlining) but it seems that GCC is managing to optimize to the point that it eliminates the problematic allocations. This theory is supported by the fact that GCC can be made to fail in the same way by changing inline, __inline, __inline__, and __always_inline in include/linux/compiler-gcc.h such that they don't actually inline things. Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com> Acked-by: Pekka Enberg <penberg@kernel.org> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jason Low | 4db0c3c298 |
mm: remove rest of ACCESS_ONCE() usages
We converted some of the usages of ACCESS_ONCE to READ_ONCE in the mm/ tree since it doesn't work reliably on non-scalar types. This patch removes the rest of the usages of ACCESS_ONCE, and use the new READ_ONCE API for the read accesses. This makes things cleaner, instead of using separate/multiple sets of APIs. Signed-off-by: Jason Low <jason.low2@hp.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Joe Perches | 6f6528a163 |
slub: use bool function return values of true/false not 1/0
Use the normal return values for bool functions Signed-off-by: Joe Perches <joe@perches.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Chris J Arges | 08303a73c6 |
mm/slub.c: parse slub_debug O option in switch statement
By moving the O option detection into the switch statement, we allow this parameter to be combined with other options correctly. Previously options like slub_debug=OFZ would only detect the 'o' and use DEBUG_DEFAULT_FLAGS to fill in the rest of the flags. Signed-off-by: Chris J Arges <chris.j.arges@canonical.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mark Rutland | 859b7a0e89 |
mm/slub: fix lockups on PREEMPT && !SMP kernels
Commit
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Andrey Ryabinin | 0316bec22e |
mm: slub: add kernel address sanitizer support for slub allocator
With this patch kasan will be able to catch bugs in memory allocated by slub. Initially all objects in newly allocated slab page, marked as redzone. Later, when allocation of slub object happens, requested by caller number of bytes marked as accessible, and the rest of the object (including slub's metadata) marked as redzone (inaccessible). We also mark object as accessible if ksize was called for this object. There is some places in kernel where ksize function is called to inquire size of really allocated area. Such callers could validly access whole allocated memory, so it should be marked as accessible. Code in slub.c and slab_common.c files could validly access to object's metadata, so instrumentation for this files are disabled. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Signed-off-by: Dmitry Chernenkov <dmitryc@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrey Ryabinin | a79316c617 |
mm: slub: introduce metadata_access_enable()/metadata_access_disable()
It's ok for slub to access memory that marked by kasan as inaccessible (object's metadata). Kasan shouldn't print report in that case because these accesses are valid. Disabling instrumentation of slub.c code is not enough to achieve this because slub passes pointer to object's metadata into external functions like memchr_inv(). We don't want to disable instrumentation for memchr_inv() because this is quite generic function, and we don't want to miss bugs. metadata_access_enable/metadata_access_disable used to tell KASan where accesses to metadata starts/end, so we could temporarily disable KASan reports. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrey Ryabinin | 75c66def8d |
mm: slub: share object_err function
Remove static and add function declarations to linux/slub_def.h so it could be used by kernel address sanitizer. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Tejun Heo | 5024c1d71b |
slub: use %*pb[l] to print bitmaps including cpumasks and nodemasks
printk and friends can now format bitmaps using '%*pb[l]'. cpumask and nodemask also provide cpumask_pr_args() and nodemask_pr_args() respectively which can be used to generate the two printf arguments necessary to format the specified cpu/nodemask. * This is an equivalent conversion but the whole function should be converted to use scnprinf famiily of functions rather than performing custom output length predictions in multiple places. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov | d6e0b7fa11 |
slub: make dead caches discard free slabs immediately
To speed up further allocations SLUB may store empty slabs in per cpu/node partial lists instead of freeing them immediately. This prevents per memcg caches destruction, because kmem caches created for a memory cgroup are only destroyed after the last page charged to the cgroup is freed. To fix this issue, this patch resurrects approach first proposed in [1]. It forbids SLUB to cache empty slabs after the memory cgroup that the cache belongs to was destroyed. It is achieved by setting kmem_cache's cpu_partial and min_partial constants to 0 and tuning put_cpu_partial() so that it would drop frozen empty slabs immediately if cpu_partial = 0. The runtime overhead is minimal. From all the hot functions, we only touch relatively cold put_cpu_partial(): we make it call unfreeze_partials() after freezing a slab that belongs to an offline memory cgroup. Since slab freezing exists to avoid moving slabs from/to a partial list on free/alloc, and there can't be allocations from dead caches, it shouldn't cause any overhead. We do have to disable preemption for put_cpu_partial() to achieve that though. The original patch was accepted well and even merged to the mm tree. However, I decided to withdraw it due to changes happening to the memcg core at that time. I had an idea of introducing per-memcg shrinkers for kmem caches, but now, as memcg has finally settled down, I do not see it as an option, because SLUB shrinker would be too costly to call since SLUB does not keep free slabs on a separate list. Besides, we currently do not even call per-memcg shrinkers for offline memcgs. Overall, it would introduce much more complexity to both SLUB and memcg than this small patch. Regarding to SLAB, there's no problem with it, because it shrinks per-cpu/node caches periodically. Thanks to list_lru reparenting, we no longer keep entries for offline cgroups in per-memcg arrays (such as memcg_cache_params->memcg_caches), so we do not have to bother if a per-memcg cache will be shrunk a bit later than it could be. [1] http://thread.gmane.org/gmane.linux.kernel.mm/118649/focus=118650 Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov | ce3712d74d |
slub: fix kmem_cache_shrink return value
It is supposed to return 0 if the cache has no remaining objects and 1 otherwise, while currently it always returns 0. Fix it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov | 832f37f5d5 |
slub: never fail to shrink cache
SLUB's version of __kmem_cache_shrink() not only removes empty slabs, but also tries to rearrange the partial lists to place slabs filled up most to the head to cope with fragmentation. To achieve that, it allocates a temporary array of lists used to sort slabs by the number of objects in use. If the allocation fails, the whole procedure is aborted. This is unacceptable for the kernel memory accounting extension of the memory cgroup, where we want to make sure that kmem_cache_shrink() successfully discarded empty slabs. Although the allocation failure is utterly unlikely with the current page allocator implementation, which retries GFP_KERNEL allocations of order <= 2 infinitely, it is better not to rely on that. This patch therefore makes __kmem_cache_shrink() allocate the array on stack instead of calling kmalloc, which may fail. The array size is chosen to be equal to 32, because most SLUB caches store not more than 32 objects per slab page. Slab pages with <= 32 free objects are sorted using the array by the number of objects in use and promoted to the head of the partial list, while slab pages with > 32 free objects are left in the end of the list without any ordering imposed on them. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Huang Ying <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov | 426589f571 |
slab: link memcg caches of the same kind into a list
Sometimes, we need to iterate over all memcg copies of a particular root kmem cache. Currently, we use memcg_cache_params->memcg_caches array for that, because it contains all existing memcg caches. However, it's a bad practice to keep all caches, including those that belong to offline cgroups, in this array, because it will be growing beyond any bounds then. I'm going to wipe away dead caches from it to save space. To still be able to perform iterations over all memcg caches of the same kind, let us link them into a list. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov | f7ce3190c4 |
slab: embed memcg_cache_params to kmem_cache
Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Kim Phillips | 94e4d712eb |
mm/slub.c: fix typo in comment
Signed-off-by: Kim Phillips <kim.phillips@freescale.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Joonsoo Kim | 9aabf810a6 |
mm/slub: optimize alloc/free fastpath by removing preemption on/off
We had to insert a preempt enable/disable in the fastpath a while ago in order to guarantee that tid and kmem_cache_cpu are retrieved on the same cpu. It is the problem only for CONFIG_PREEMPT in which scheduler can move the process to other cpu during retrieving data. Now, I reach the solution to remove preempt enable/disable in the fastpath. If tid is matched with kmem_cache_cpu's tid after tid and kmem_cache_cpu are retrieved by separate this_cpu operation, it means that they are retrieved on the same cpu. If not matched, we just have to retry it. With this guarantee, preemption enable/disable isn't need at all even if CONFIG_PREEMPT, so this patch removes it. I saw roughly 5% win in a fast-path loop over kmem_cache_alloc/free in CONFIG_PREEMPT. (14.821 ns -> 14.049 ns) Below is the result of Christoph's slab_test reported by Jesper Dangaard Brouer. * Before Single thread testing ===================== 1. Kmalloc: Repeatedly allocate then free test 10000 times kmalloc(8) -> 49 cycles kfree -> 62 cycles 10000 times kmalloc(16) -> 48 cycles kfree -> 64 cycles 10000 times kmalloc(32) -> 53 cycles kfree -> 70 cycles 10000 times kmalloc(64) -> 64 cycles kfree -> 77 cycles 10000 times kmalloc(128) -> 74 cycles kfree -> 84 cycles 10000 times kmalloc(256) -> 84 cycles kfree -> 114 cycles 10000 times kmalloc(512) -> 83 cycles kfree -> 116 cycles 10000 times kmalloc(1024) -> 81 cycles kfree -> 120 cycles 10000 times kmalloc(2048) -> 104 cycles kfree -> 136 cycles 10000 times kmalloc(4096) -> 142 cycles kfree -> 165 cycles 10000 times kmalloc(8192) -> 238 cycles kfree -> 226 cycles 10000 times kmalloc(16384) -> 403 cycles kfree -> 264 cycles 2. Kmalloc: alloc/free test 10000 times kmalloc(8)/kfree -> 68 cycles 10000 times kmalloc(16)/kfree -> 68 cycles 10000 times kmalloc(32)/kfree -> 69 cycles 10000 times kmalloc(64)/kfree -> 68 cycles 10000 times kmalloc(128)/kfree -> 68 cycles 10000 times kmalloc(256)/kfree -> 68 cycles 10000 times kmalloc(512)/kfree -> 74 cycles 10000 times kmalloc(1024)/kfree -> 75 cycles 10000 times kmalloc(2048)/kfree -> 74 cycles 10000 times kmalloc(4096)/kfree -> 74 cycles 10000 times kmalloc(8192)/kfree -> 75 cycles 10000 times kmalloc(16384)/kfree -> 510 cycles * After Single thread testing ===================== 1. Kmalloc: Repeatedly allocate then free test 10000 times kmalloc(8) -> 46 cycles kfree -> 61 cycles 10000 times kmalloc(16) -> 46 cycles kfree -> 63 cycles 10000 times kmalloc(32) -> 49 cycles kfree -> 69 cycles 10000 times kmalloc(64) -> 57 cycles kfree -> 76 cycles 10000 times kmalloc(128) -> 66 cycles kfree -> 83 cycles 10000 times kmalloc(256) -> 84 cycles kfree -> 110 cycles 10000 times kmalloc(512) -> 77 cycles kfree -> 114 cycles 10000 times kmalloc(1024) -> 80 cycles kfree -> 116 cycles 10000 times kmalloc(2048) -> 102 cycles kfree -> 131 cycles 10000 times kmalloc(4096) -> 135 cycles kfree -> 163 cycles 10000 times kmalloc(8192) -> 238 cycles kfree -> 218 cycles 10000 times kmalloc(16384) -> 399 cycles kfree -> 262 cycles 2. Kmalloc: alloc/free test 10000 times kmalloc(8)/kfree -> 65 cycles 10000 times kmalloc(16)/kfree -> 66 cycles 10000 times kmalloc(32)/kfree -> 65 cycles 10000 times kmalloc(64)/kfree -> 66 cycles 10000 times kmalloc(128)/kfree -> 66 cycles 10000 times kmalloc(256)/kfree -> 71 cycles 10000 times kmalloc(512)/kfree -> 72 cycles 10000 times kmalloc(1024)/kfree -> 71 cycles 10000 times kmalloc(2048)/kfree -> 71 cycles 10000 times kmalloc(4096)/kfree -> 71 cycles 10000 times kmalloc(8192)/kfree -> 65 cycles 10000 times kmalloc(16384)/kfree -> 511 cycles Most of the results are better than before. Note that this change slightly worses performance in !CONFIG_PREEMPT, roughly 0.3%. Implementing each case separately would help performance, but, since it's so marginal, I didn't do that. This would help maintanance since we have same code for all cases. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Christoph Lameter <cl@linux.com> Tested-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov | dee2f8aaab |
slub: fix cpuset check in get_any_partial
If we fail to allocate from the current node's stock, we look for free objects on other nodes before calling the page allocator (see get_any_partial). While checking other nodes we respect cpuset constraints by calling cpuset_zone_allowed. We enforce hardwall check. As a result, we will fallback to the page allocator even if there are some pages cached on other nodes, but the current cpuset doesn't have them set. However, the page allocator uses softwall check for kernel allocations, so it may allocate from one of the other nodes in this case. Therefore we should use softwall cpuset check in get_any_partial to conform with the cpuset check in the page allocator. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Zefan Li <lizefan@huawei.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov | 8135be5a80 |
memcg: fix possible use-after-free in memcg_kmem_get_cache()
Suppose task @t that belongs to a memory cgroup @memcg is going to allocate an object from a kmem cache @c. The copy of @c corresponding to @memcg, @mc, is empty. Then if kmem_cache_alloc races with the memory cgroup destruction we can access the memory cgroup's copy of the cache after it was destroyed: CPU0 CPU1 ---- ---- [ current=@t @mc->memcg_params->nr_pages=0 ] kmem_cache_alloc(@c): call memcg_kmem_get_cache(@c); proceed to allocation from @mc: alloc a page for @mc: ... move @t from @memcg destroy @memcg: mem_cgroup_css_offline(@memcg): memcg_unregister_all_caches(@memcg): kmem_cache_destroy(@mc) add page to @mc We could fix this issue by taking a reference to a per-memcg cache, but that would require adding a per-cpu reference counter to per-memcg caches, which would look cumbersome. Instead, let's take a reference to a memory cgroup, which already has a per-cpu reference counter, in the beginning of kmem_cache_alloc to be dropped in the end, and move per memcg caches destruction from css offline to css free. As a side effect, per-memcg caches will be destroyed not one by one, but all at once when the last page accounted to the memory cgroup is freed. This doesn't sound as a high price for code readability though. Note, this patch does add some overhead to the kmem_cache_alloc hot path, but it is pretty negligible - it's just a function call plus a per cpu counter decrement, which is comparable to what we already have in memcg_kmem_get_cache. Besides, it's only relevant if there are memory cgroups with kmem accounting enabled. I don't think we can find a way to handle this race w/o it, because alloc_page called from kmem_cache_alloc may sleep so we can't flush all pending kmallocs w/o reference counting. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds | 2756d373a3 |
Merge branch 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup update from Tejun Heo: "cpuset got simplified a bit. cgroup core got a fix on unified hierarchy and grew some effective css related interfaces which will be used for blkio support for writeback IO traffic which is currently being worked on" * 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: implement cgroup_get_e_css() cgroup: add cgroup_subsys->css_e_css_changed() cgroup: add cgroup_subsys->css_released() cgroup: fix the async css offline wait logic in cgroup_subtree_control_write() cgroup: restructure child_subsys_mask handling in cgroup_subtree_control_write() cgroup: separate out cgroup_calc_child_subsys_mask() from cgroup_refresh_child_subsys_mask() cpuset: lock vs unlock typo cpuset: simplify cpuset_node_allowed API cpuset: convert callback_mutex to a spinlock |
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Andrew Morton | c871ac4e96 |
slab: improve checking for invalid gfp_flags
The code goes BUG, but doesn't tell us which bits were unexpectedly set. Print that out. Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrey Ryabinin | f6edde9cbe |
mm: slub: fix format mismatches in slab_err() callers
Adding __printf(3, 4) to slab_err exposed following: mm/slub.c: In function `check_slab': mm/slub.c:852:4: warning: format `%u' expects argument of type `unsigned int', but argument 4 has type `const char *' [-Wformat=] s->name, page->objects, maxobj); ^ mm/slub.c:852:4: warning: too many arguments for format [-Wformat-extra-args] mm/slub.c:857:4: warning: format `%u' expects argument of type `unsigned int', but argument 4 has type `const char *' [-Wformat=] s->name, page->inuse, page->objects); ^ mm/slub.c:857:4: warning: too many arguments for format [-Wformat-extra-args] mm/slub.c: In function `on_freelist': mm/slub.c:905:4: warning: format `%d' expects argument of type `int', but argument 5 has type `long unsigned int' [-Wformat=] "should be %d", page->objects, max_objects); Fix first two warnings by removing redundant s->name. Fix the last by changing type of max_object from unsigned long to int. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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LQYMGT | b455def28d |
mm: slab/slub: coding style: whitespaces and tabs mixture
Some code in mm/slab.c and mm/slub.c use whitespaces in indent. Clean them up. Signed-off-by: LQYMGT <lqymgt@gmail.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov | 344736f29b |
cpuset: simplify cpuset_node_allowed API
Current cpuset API for checking if a zone/node is allowed to allocate
from looks rather awkward. We have hardwall and softwall versions of
cpuset_node_allowed with the softwall version doing literally the same
as the hardwall version if __GFP_HARDWALL is passed to it in gfp flags.
If it isn't, the softwall version may check the given node against the
enclosing hardwall cpuset, which it needs to take the callback lock to
do.
Such a distinction was introduced by commit
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Joonsoo Kim | 423c929cbb |
mm/slab_common: commonize slab merge logic
Slab merge is good feature to reduce fragmentation. Now, it is only applied to SLUB, but, it would be good to apply it to SLAB. This patch is preparation step to apply slab merge to SLAB by commonizing slab merge logic. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |