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2017-01-24mm, memcg: do not retry precharge chargesDavid Rientjes1-2/+2
When memory.move_charge_at_immigrate is enabled and precharges are depleted during move, mem_cgroup_move_charge_pte_range() will attempt to increase the size of the precharge. Prevent precharges from ever looping by setting __GFP_NORETRY. This was probably the intention of the GFP_KERNEL & ~__GFP_NORETRY, which is pointless as written. Fixes: 0029e19ebf84 ("mm: memcontrol: remove explicit OOM parameter in charge path") Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1701130208510.69402@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-10mm, memcg: fix the active list aging for lowmem requests when memcg is enabledMichal Hocko1-10/+8
Nils Holland and Klaus Ethgen have reported unexpected OOM killer invocations with 32b kernel starting with 4.8 kernels kworker/u4:5 invoked oom-killer: gfp_mask=0x2400840(GFP_NOFS|__GFP_NOFAIL), nodemask=0, order=0, oom_score_adj=0 kworker/u4:5 cpuset=/ mems_allowed=0 CPU: 1 PID: 2603 Comm: kworker/u4:5 Not tainted 4.9.0-gentoo #2 [...] Mem-Info: active_anon:58685 inactive_anon:90 isolated_anon:0 active_file:274324 inactive_file:281962 isolated_file:0 unevictable:0 dirty:649 writeback:0 unstable:0 slab_reclaimable:40662 slab_unreclaimable:17754 mapped:7382 shmem:202 pagetables:351 bounce:0 free:206736 free_pcp:332 free_cma:0 Node 0 active_anon:234740kB inactive_anon:360kB active_file:1097296kB inactive_file:1127848kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:29528kB dirty:2596kB writeback:0kB shmem:0kB shmem_thp: 0kB shmem_pmdmapped: 184320kB anon_thp: 808kB writeback_tmp:0kB unstable:0kB pages_scanned:0 all_unreclaimable? no DMA free:3952kB min:788kB low:984kB high:1180kB active_anon:0kB inactive_anon:0kB active_file:7316kB inactive_file:0kB unevictable:0kB writepending:96kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:3200kB slab_unreclaimable:1408kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 813 3474 3474 Normal free:41332kB min:41368kB low:51708kB high:62048kB active_anon:0kB inactive_anon:0kB active_file:532748kB inactive_file:44kB unevictable:0kB writepending:24kB present:897016kB managed:836248kB mlocked:0kB slab_reclaimable:159448kB slab_unreclaimable:69608kB kernel_stack:1112kB pagetables:1404kB bounce:0kB free_pcp:528kB local_pcp:340kB free_cma:0kB lowmem_reserve[]: 0 0 21292 21292 HighMem free:781660kB min:512kB low:34356kB high:68200kB active_anon:234740kB inactive_anon:360kB active_file:557232kB inactive_file:1127804kB unevictable:0kB writepending:2592kB present:2725384kB managed:2725384kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:800kB local_pcp:608kB free_cma:0kB the oom killer is clearly pre-mature because there there is still a lot of page cache in the zone Normal which should satisfy this lowmem request. Further debugging has shown that the reclaim cannot make any forward progress because the page cache is hidden in the active list which doesn't get rotated because inactive_list_is_low is not memcg aware. The code simply subtracts per-zone highmem counters from the respective memcg's lru sizes which doesn't make any sense. We can simply end up always seeing the resulting active and inactive counts 0 and return false. This issue is not limited to 32b kernels but in practice the effect on systems without CONFIG_HIGHMEM would be much harder to notice because we do not invoke the OOM killer for allocations requests targeting < ZONE_NORMAL. Fix the issue by tracking per zone lru page counts in mem_cgroup_per_node and subtract per-memcg highmem counts when memcg is enabled. Introduce helper lruvec_zone_lru_size which redirects to either zone counters or mem_cgroup_get_zone_lru_size when appropriate. We are losing empty LRU but non-zero lru size detection introduced by ca707239e8a7 ("mm: update_lru_size warn and reset bad lru_size") because of the inherent zone vs. node discrepancy. Fixes: f8d1a31163fc ("mm: consider whether to decivate based on eligible zones inactive ratio") Link: http://lkml.kernel.org/r/20170104100825.3729-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Nils Holland <nholland@tisys.org> Tested-by: Nils Holland <nholland@tisys.org> Reported-by: Klaus Ethgen <Klaus@Ethgen.de> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-24Replace <asm/uaccess.h> with <linux/uaccess.h> globallyLinus Torvalds1-1/+1
This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-12Merge branch 'akpm' (patches from Andrew)Linus Torvalds1-1/+14
Merge updates from Andrew Morton: - various misc bits - most of MM (quite a lot of MM material is awaiting the merge of linux-next dependencies) - kasan - printk updates - procfs updates - MAINTAINERS - /lib updates - checkpatch updates * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (123 commits) init: reduce rootwait polling interval time to 5ms binfmt_elf: use vmalloc() for allocation of vma_filesz checkpatch: don't emit unified-diff error for rename-only patches checkpatch: don't check c99 types like uint8_t under tools checkpatch: avoid multiple line dereferences checkpatch: don't check .pl files, improve absolute path commit log test scripts/checkpatch.pl: fix spelling checkpatch: don't try to get maintained status when --no-tree is given lib/ida: document locking requirements a bit better lib/rbtree.c: fix typo in comment of ____rb_erase_color lib/Kconfig.debug: make CONFIG_STRICT_DEVMEM depend on CONFIG_DEVMEM MAINTAINERS: add drm and drm/i915 irc channels MAINTAINERS: add "C:" for URI for chat where developers hang out MAINTAINERS: add drm and drm/i915 bug filing info MAINTAINERS: add "B:" for URI where to file bugs get_maintainer: look for arbitrary letter prefixes in sections printk: add Kconfig option to set default console loglevel printk/sound: handle more message headers printk/btrfs: handle more message headers printk/kdb: handle more message headers ...
2016-12-12mm: memcontrol: use special workqueue for creating per-memcg cachesVladimir Davydov1-1/+14
Creating a lot of cgroups at the same time might stall all worker threads with kmem cache creation works, because kmem cache creation is done with the slab_mutex held. The problem was amplified by commits 801faf0db894 ("mm/slab: lockless decision to grow cache") in case of SLAB and 81ae6d03952c ("mm/slub.c: replace kick_all_cpus_sync() with synchronize_sched() in kmem_cache_shrink()") in case of SLUB, which increased the maximal time the slab_mutex can be held. To prevent that from happening, let's use a special ordered single threaded workqueue for kmem cache creation. This shouldn't introduce any functional changes regarding how kmem caches are created, as the work function holds the global slab_mutex during its whole runtime anyway, making it impossible to run more than one work at a time. By using a single threaded workqueue, we just avoid creating a thread per each work. Ordering is required to avoid a situation when a cgroup's work is put off indefinitely because there are other cgroups to serve, in other words to guarantee fairness. Link: https://bugzilla.kernel.org/show_bug.cgi?id=172981 Link: http://lkml.kernel.org/r/20161004131417.GC1862@esperanza Signed-off-by: Vladimir Davydov <vdavydov.dev@gmail.com> Reported-by: Doug Smythies <dsmythies@telus.net> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.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>
2016-11-09mm/memcg: Convert to hotplug state machineSebastian Andrzej Siewior1-16/+8
Install the callbacks via the state machine. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: linux-mm@kvack.org Cc: rt@linutronix.de Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: cgroups@vger.kernel.org Link: http://lkml.kernel.org/r/20161103145021.28528-4-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-10-27mm: memcontrol: do not recurse in direct reclaimJohannes Weiner1-0/+9
On 4.0, we saw a stack corruption from a page fault entering direct memory cgroup reclaim, calling into btrfs_releasepage(), which then tried to allocate an extent and recursed back into a kmem charge ad nauseam: [...] btrfs_releasepage+0x2c/0x30 try_to_release_page+0x32/0x50 shrink_page_list+0x6da/0x7a0 shrink_inactive_list+0x1e5/0x510 shrink_lruvec+0x605/0x7f0 shrink_zone+0xee/0x320 do_try_to_free_pages+0x174/0x440 try_to_free_mem_cgroup_pages+0xa7/0x130 try_charge+0x17b/0x830 memcg_charge_kmem+0x40/0x80 new_slab+0x2d9/0x5a0 __slab_alloc+0x2fd/0x44f kmem_cache_alloc+0x193/0x1e0 alloc_extent_state+0x21/0xc0 __clear_extent_bit+0x2b5/0x400 try_release_extent_mapping+0x1a3/0x220 __btrfs_releasepage+0x31/0x70 btrfs_releasepage+0x2c/0x30 try_to_release_page+0x32/0x50 shrink_page_list+0x6da/0x7a0 shrink_inactive_list+0x1e5/0x510 shrink_lruvec+0x605/0x7f0 shrink_zone+0xee/0x320 do_try_to_free_pages+0x174/0x440 try_to_free_mem_cgroup_pages+0xa7/0x130 try_charge+0x17b/0x830 mem_cgroup_try_charge+0x65/0x1c0 handle_mm_fault+0x117f/0x1510 __do_page_fault+0x177/0x420 do_page_fault+0xc/0x10 page_fault+0x22/0x30 On later kernels, kmem charging is opt-in rather than opt-out, and that particular kmem allocation in btrfs_releasepage() is no longer being charged and won't recurse and overrun the stack anymore. But it's not impossible for an accounted allocation to happen from the memcg direct reclaim context, and we needed to reproduce this crash many times before we even got a useful stack trace out of it. Like other direct reclaimers, mark tasks in memcg reclaim PF_MEMALLOC to avoid recursing into any other form of direct reclaim. Then let recursive charges from PF_MEMALLOC contexts bypass the cgroup limit. Link: http://lkml.kernel.org/r/20161025141050.GA13019@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07mm: memcontrol: consolidate cgroup socket trackingJohannes Weiner1-10/+13
The cgroup core and the memory controller need to track socket ownership for different purposes, but the tracking sites being entirely different is kind of ugly. Be a better citizen and rename the memory controller callbacks to match the cgroup core callbacks, then move them to the same place. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20160914194846.11153-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07mm, swap: use offset of swap entry as key of swap cacheHuang Ying1-2/+3
This patch is to improve the performance of swap cache operations when the type of the swap device is not 0. Originally, the whole swap entry value is used as the key of the swap cache, even though there is one radix tree for each swap device. If the type of the swap device is not 0, the height of the radix tree of the swap cache will be increased unnecessary, especially on 64bit architecture. For example, for a 1GB swap device on the x86_64 architecture, the height of the radix tree of the swap cache is 11. But if the offset of the swap entry is used as the key of the swap cache, the height of the radix tree of the swap cache is 4. The increased height causes unnecessary radix tree descending and increased cache footprint. This patch reduces the height of the radix tree of the swap cache via using the offset of the swap entry instead of the whole swap entry value as the key of the swap cache. In 32 processes sequential swap out test case on a Xeon E5 v3 system with RAM disk as swap, the lock contention for the spinlock of the swap cache is reduced from 20.15% to 12.19%, when the type of the swap device is 1. Use the whole swap entry as key, perf-profile.calltrace.cycles-pp._raw_spin_lock_irq.__add_to_swap_cache.add_to_swap_cache.add_to_swap.shrink_page_list: 10.37, perf-profile.calltrace.cycles-pp._raw_spin_lock_irqsave.__remove_mapping.shrink_page_list.shrink_inactive_list.shrink_node_memcg: 9.78, Use the swap offset as key, perf-profile.calltrace.cycles-pp._raw_spin_lock_irq.__add_to_swap_cache.add_to_swap_cache.add_to_swap.shrink_page_list: 6.25, perf-profile.calltrace.cycles-pp._raw_spin_lock_irqsave.__remove_mapping.shrink_page_list.shrink_inactive_list.shrink_node_memcg: 5.94, Link: http://lkml.kernel.org/r/1473270649-27229-1-git-send-email-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Minchan Kim <minchan@kernel.org> Cc: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07mm/memcontrol.c: make the walk_page_range() limit obviousJames Morse1-2/+4
mem_cgroup_count_precharge() and mem_cgroup_move_charge() both call walk_page_range() on the range 0 to ~0UL, neither provide a pte_hole callback, which causes the current implementation to skip non-vma regions. This is all fine but follow up changes would like to make walk_page_range more generic so it is better to be explicit about which range to traverse so let's use highest_vm_end to explicitly traverse only user mmaped memory. [mhocko@kernel.org: rewrote changelog] Link: http://lkml.kernel.org/r/1472655897-22532-1-git-send-email-james.morse@arm.com Signed-off-by: James Morse <james.morse@arm.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07mm: memcontrol: add sanity checks for memcg->id.ref on get/putVladimir Davydov1-1/+5
Link: http://lkml.kernel.org/r/1c5ddb1c171dbdfc3262252769d6138a29b35b70.1470219853.git.vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07mm: oom: deduplicate victim selection code for memcg and global oomVladimir Davydov1-72/+42
When selecting an oom victim, we use the same heuristic for both memory cgroup and global oom. The only difference is the scope of tasks to select the victim from. So we could just export an iterator over all memcg tasks and keep all oom related logic in oom_kill.c, but instead we duplicate pieces of it in memcontrol.c reusing some initially private functions of oom_kill.c in order to not duplicate all of it. That looks ugly and error prone, because any modification of select_bad_process should also be propagated to mem_cgroup_out_of_memory. Let's rework this as follows: keep all oom heuristic related code private to oom_kill.c and make oom_kill.c use exported memcg functions when it's really necessary (like in case of iterating over memcg tasks). Link: http://lkml.kernel.org/r/1470056933-7505-1-git-send-email-vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-09-19mm: memcontrol: make per-cpu charge cache IRQ-safe for socket accountingJohannes Weiner1-9/+22
During cgroup2 rollout into production, we started encountering css refcount underflows and css access crashes in the memory controller. Splitting the heavily shared css reference counter into logical users narrowed the imbalance down to the cgroup2 socket memory accounting. The problem turns out to be the per-cpu charge cache. Cgroup1 had a separate socket counter, but the new cgroup2 socket accounting goes through the common charge path that uses a shared per-cpu cache for all memory that is being tracked. Those caches are safe against scheduling preemption, but not against interrupts - such as the newly added packet receive path. When cache draining is interrupted by network RX taking pages out of the cache, the resuming drain operation will put references of in-use pages, thus causing the imbalance. Disable IRQs during all per-cpu charge cache operations. Fixes: f7e1cb6ec51b ("mm: memcontrol: account socket memory in unified hierarchy memory controller") Link: http://lkml.kernel.org/r/20160914194846.11153-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: <stable@vger.kernel.org> [4.5+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-26mm: memcontrol: avoid unused function warningArnd Bergmann1-18/+18
A bugfix in v4.8-rc2 introduced a harmless warning when CONFIG_MEMCG_SWAP is disabled but CONFIG_MEMCG is enabled: mm/memcontrol.c:4085:27: error: 'mem_cgroup_id_get_online' defined but not used [-Werror=unused-function] static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) This moves the function inside of the #ifdef block that hides the calling function, to avoid the warning. Fixes: 1f47b61fb407 ("mm: memcontrol: fix swap counter leak on swapout from offline cgroup") Link: http://lkml.kernel.org/r/20160824113733.2776701-1-arnd@arndb.de Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-11mm: memcontrol: fix memcg id ref counter on swap charge moveVladimir Davydov1-6/+18
Since commit 73f576c04b94 ("mm: memcontrol: fix cgroup creation failure after many small jobs") swap entries do not pin memcg->css.refcnt directly. Instead, they pin memcg->id.ref. So we should adjust the reference counters accordingly when moving swap charges between cgroups. Fixes: 73f576c04b941 ("mm: memcontrol: fix cgroup creation failure after many small jobs") Link: http://lkml.kernel.org/r/9ce297c64954a42dc90b543bc76106c4a94f07e8.1470219853.git.vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> [3.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-11mm: memcontrol: fix swap counter leak on swapout from offline cgroupVladimir Davydov1-6/+38
An offline memory cgroup might have anonymous memory or shmem left charged to it and no swap. Since only swap entries pin the id of an offline cgroup, such a cgroup will have no id and so an attempt to swapout its anon/shmem will not store memory cgroup info in the swap cgroup map. As a result, memcg->swap or memcg->memsw will never get uncharged from it and any of its ascendants. Fix this by always charging swapout to the first ancestor cgroup that hasn't released its id yet. [hannes@cmpxchg.org: add comment to mem_cgroup_swapout] [vdavydov@virtuozzo.com: use WARN_ON_ONCE() in mem_cgroup_id_get_online()] Link: http://lkml.kernel.org/r/20160803123445.GJ13263@esperanza Fixes: 73f576c04b941 ("mm: memcontrol: fix cgroup creation failure after many small jobs") Link: http://lkml.kernel.org/r/5336daa5c9a32e776067773d9da655d2dc126491.1470219853.git.vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> [3.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-09mm: memcontrol: only mark charged pages with PageKmemcgVladimir Davydov1-2/+12
To distinguish non-slab pages charged to kmemcg we mark them PageKmemcg, which sets page->_mapcount to -512. Currently, we set/clear PageKmemcg in __alloc_pages_nodemask()/free_pages_prepare() for any page allocated with __GFP_ACCOUNT, including those that aren't actually charged to any cgroup, i.e. allocated from the root cgroup context. To avoid overhead in case cgroups are not used, we only do that if memcg_kmem_enabled() is true. The latter is set iff there are kmem-enabled memory cgroups (online or offline). The root cgroup is not considered kmem-enabled. As a result, if a page is allocated with __GFP_ACCOUNT for the root cgroup when there are kmem-enabled memory cgroups and is freed after all kmem-enabled memory cgroups were removed, e.g. # no memory cgroups has been created yet, create one mkdir /sys/fs/cgroup/memory/test # run something allocating pages with __GFP_ACCOUNT, e.g. # a program using pipe dmesg | tail # remove the memory cgroup rmdir /sys/fs/cgroup/memory/test we'll get bad page state bug complaining about page->_mapcount != -1: BUG: Bad page state in process swapper/0 pfn:1fd945c page:ffffea007f651700 count:0 mapcount:-511 mapping: (null) index:0x0 flags: 0x1000000000000000() To avoid that, let's mark with PageKmemcg only those pages that are actually charged to and hence pin a non-root memory cgroup. Fixes: 4949148ad433 ("mm: charge/uncharge kmemcg from generic page allocator paths") Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-02memcg: put soft limit reclaim out of way if the excess tree is emptyMichal Hocko1-0/+9
We've had a report about soft lockups caused by lock bouncing in the soft reclaim path: BUG: soft lockup - CPU#0 stuck for 22s! [kav4proxy-kavic:3128] RIP: 0010:[<ffffffff81469798>] [<ffffffff81469798>] _raw_spin_lock+0x18/0x20 Call Trace: mem_cgroup_soft_limit_reclaim+0x25a/0x280 shrink_zones+0xed/0x200 do_try_to_free_pages+0x74/0x320 try_to_free_pages+0x112/0x180 __alloc_pages_slowpath+0x3ff/0x820 __alloc_pages_nodemask+0x1e9/0x200 alloc_pages_vma+0xe1/0x290 do_wp_page+0x19f/0x840 handle_pte_fault+0x1cd/0x230 do_page_fault+0x1fd/0x4c0 page_fault+0x25/0x30 There are no memcgs created so there cannot be any in the soft limit excess obviously: [...] memory 0 1 1 so all this just seems to be mem_cgroup_largest_soft_limit_node trying to get spin_lock_irq(&mctz->lock) just to find out that the soft limit excess tree is empty. This is just pointless wasting of cycles and cache line bouncing during heavy parallel reclaim on large machines. The particular machine wasn't very healthy and most probably suffering from a memory leak which just caused the memory reclaim to trash heavily. But bouncing on the lock certainly didn't help... Fix this by optimistic lockless check and bail out early if the tree is empty. This is theoretically racy but that shouldn't matter all that much. First of all soft limit is a best effort feature and it is slowly getting deprecated and its usage should be really scarce. Bouncing on a lock without a good reason is surely much bigger problem, especially on large CPU machines. Link: http://lkml.kernel.org/r/1470073277-1056-1-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-28mm: fix memcg stack accounting for sub-page stacksAndy Lutomirski1-1/+1
We should account for stacks regardless of stack size, and we need to account in sub-page units if THREAD_SIZE < PAGE_SIZE. Change the units to kilobytes and Move it into account_kernel_stack(). Fixes: 12580e4b54ba8 ("mm: memcontrol: report kernel stack usage in cgroup2 memory.stat") Link: http://lkml.kernel.org/r/9b5314e3ee5eda61b0317ec1563768602c1ef438.1468523549.git.luto@kernel.org Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-28mm, vmscan: Update all zone LRU sizes before updating memcgMel Gorman1-4/+1
Minchan Kim reported setting the following warning on a 32-bit system although it can affect 64-bit systems. WARNING: CPU: 4 PID: 1322 at mm/memcontrol.c:998 mem_cgroup_update_lru_size+0x103/0x110 mem_cgroup_update_lru_size(f44b4000, 1, -7): zid 1 lru_size 1 but empty Modules linked in: CPU: 4 PID: 1322 Comm: cp Not tainted 4.7.0-rc4-mm1+ #143 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: dump_stack+0x76/0xaf __warn+0xea/0x110 ? mem_cgroup_update_lru_size+0x103/0x110 warn_slowpath_fmt+0x3b/0x40 mem_cgroup_update_lru_size+0x103/0x110 isolate_lru_pages.isra.61+0x2e2/0x360 shrink_active_list+0xac/0x2a0 ? __delay+0xe/0x10 shrink_node_memcg+0x53c/0x7a0 shrink_node+0xab/0x2a0 do_try_to_free_pages+0xc6/0x390 try_to_free_pages+0x245/0x590 LRU list contents and counts are updated separately. Counts are updated before pages are added to the LRU and updated after pages are removed. The warning above is from a check in mem_cgroup_update_lru_size that ensures that list sizes of zero are empty. The problem is that node-lru needs to account for highmem pages if CONFIG_HIGHMEM is set. One impact of the implementation is that the sizes are updated in multiple passes when pages from multiple zones were isolated. This happens whether HIGHMEM is set or not. When multiple zones are isolated, it's possible for a debugging check in memcg to be tripped. This patch forces all the zone counts to be updated before the memcg function is called. Link: http://lkml.kernel.org/r/1468588165-12461-6-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Tested-by: Minchan Kim <minchan@kernel.org> Reported-by: Minchan Kim <minchan@kernel.org> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-28mm, memcg: move memcg limit enforcement from zones to nodesMel Gorman1-107/+83
Memcg needs adjustment after moving LRUs to the node. Limits are tracked per memcg but the soft-limit excess is tracked per zone. As global page reclaim is based on the node, it is easy to imagine a situation where a zone soft limit is exceeded even though the memcg limit is fine. This patch moves the soft limit tree the node. Technically, all the variable names should also change but people are already familiar by the meaning of "mz" even if "mn" would be a more appropriate name now. Link: http://lkml.kernel.org/r/1467970510-21195-15-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.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>
2016-07-28mm, vmscan: make shrink_node decisions more node-centricMel Gorman1-2/+2
Earlier patches focused on having direct reclaim and kswapd use data that is node-centric for reclaiming but shrink_node() itself still uses too much zone information. This patch removes unnecessary zone-based information with the most important decision being whether to continue reclaim or not. Some memcg APIs are adjusted as a result even though memcg itself still uses some zone information. [mgorman@techsingularity.net: optimization] Link: http://lkml.kernel.org/r/1468588165-12461-2-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-14-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-28mm, vmscan: move LRU lists to nodeMel Gorman1-8/+9
This moves the LRU lists from the zone to the node and related data such as counters, tracing, congestion tracking and writeback tracking. Unfortunately, due to reclaim and compaction retry logic, it is necessary to account for the number of LRU pages on both zone and node logic. Most reclaim logic is based on the node counters but the retry logic uses the zone counters which do not distinguish inactive and active sizes. It would be possible to leave the LRU counters on a per-zone basis but it's a heavier calculation across multiple cache lines that is much more frequent than the retry checks. Other than the LRU counters, this is mostly a mechanical patch but note that it introduces a number of anomalies. For example, the scans are per-zone but using per-node counters. We also mark a node as congested when a zone is congested. This causes weird problems that are fixed later but is easier to review. In the event that there is excessive overhead on 32-bit systems due to the nodes being on LRU then there are two potential solutions 1. Long-term isolation of highmem pages when reclaim is lowmem When pages are skipped, they are immediately added back onto the LRU list. If lowmem reclaim persisted for long periods of time, the same highmem pages get continually scanned. The idea would be that lowmem keeps those pages on a separate list until a reclaim for highmem pages arrives that splices the highmem pages back onto the LRU. It potentially could be implemented similar to the UNEVICTABLE list. That would reduce the skip rate with the potential corner case is that highmem pages have to be scanned and reclaimed to free lowmem slab pages. 2. Linear scan lowmem pages if the initial LRU shrink fails This will break LRU ordering but may be preferable and faster during memory pressure than skipping LRU pages. Link: http://lkml.kernel.org/r/1467970510-21195-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-28mm, vmscan: move lru_lock to the nodeMel Gorman1-3/+3
Node-based reclaim requires node-based LRUs and locking. This is a preparation patch that just moves the lru_lock to the node so later patches are easier to review. It is a mechanical change but note this patch makes contention worse because the LRU lock is hotter and direct reclaim and kswapd can contend on the same lock even when reclaiming from different zones. Link: http://lkml.kernel.org/r/1467970510-21195-3-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-28mm: fix vm-scalability regression in cgroup-aware workingset codeJohannes Weiner1-42/+0
Commit 23047a96d7cf ("mm: workingset: per-cgroup cache thrash detection") added a page->mem_cgroup lookup to the cache eviction, refault, and activation paths, as well as locking to the activation path, and the vm-scalability tests showed a regression of -23%. While the test in question is an artificial worst-case scenario that doesn't occur in real workloads - reading two sparse files in parallel at full CPU speed just to hammer the LRU paths - there is still some optimizations that can be done in those paths. Inline the lookup functions to eliminate calls. Also, page->mem_cgroup doesn't need to be stabilized when counting an activation; we merely need to hold the RCU lock to prevent the memcg from being freed. This cuts down on overhead quite a bit: 23047a96d7cfcfca 063f6715e77a7be5770d6081fe ---------------- -------------------------- %stddev %change %stddev \ | \ 21621405 +- 0% +11.3% 24069657 +- 2% vm-scalability.throughput [linux@roeck-us.net: drop unnecessary include file] [hannes@cmpxchg.org: add WARN_ON_ONCE()s] Link: http://lkml.kernel.org/r/20160707194024.GA26580@cmpxchg.org Link: http://lkml.kernel.org/r/20160624175101.GA3024@cmpxchg.org Reported-by: Ye Xiaolong <xiaolong.ye@intel.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-28mm, oom: fortify task_will_free_mem()Michal Hocko1-2/+2
task_will_free_mem is rather weak. It doesn't really tell whether the task has chance to drop its mm. 98748bd72200 ("oom: consider multi-threaded tasks in task_will_free_mem") made a first step into making it more robust for multi-threaded applications so now we know that the whole process is going down and probably drop the mm. This patch builds on top for more complex scenarios where mm is shared between different processes - CLONE_VM without CLONE_SIGHAND, or in kernel use_mm(). Make sure that all processes sharing the mm are killed or exiting. This will allow us to replace try_oom_reaper by wake_oom_reaper because task_will_free_mem implies the task is reapable now. Therefore all paths which bypass the oom killer are now reapable and so they shouldn't lock up the oom killer. Link: http://lkml.kernel.org/r/1466426628-15074-8-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: David Rientjes <rientjes@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26mm: memcontrol: fix documentation for compound parameterLi RongQing1-1/+4
Commit f627c2f53786 ("memcg: adjust to support new THP refcounting") adds a compound parameter for several functions, and change one as compound for mem_cgroup_move_account but it does not change the comments. Link: http://lkml.kernel.org/r/1465368216-9393-1-git-send-email-roy.qing.li@gmail.com Signed-off-by: Li RongQing <roy.qing.li@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26mm: memcontrol: remove BUG_ON in uncharge_listLi RongQing1-1/+0
When calling uncharge_list, if a page is transparent huge we don't need to BUG_ON about non-transparent huge, since nobody should be able to see the page at this stage and this page cannot be raced against with a THP split. This check became unneeded after 0a31bc97c80c ("mm: memcontrol: rewrite uncharge API"). [mhocko@suse.com: changelog enhancements] Link: http://lkml.kernel.org/r/1465369248-13865-1-git-send-email-roy.qing.li@gmail.com Signed-off-by: Li RongQing <roy.qing.li@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26mm,oom: remove unused argument from oom_scan_process_thread().Tetsuo Handa1-1/+1
oom_scan_process_thread() does not use totalpages argument. oom_badness() uses it. Link: http://lkml.kernel.org/r/1463796041-7889-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26mm: memcontrol: teach uncharge_list to deal with kmem pagesVladimir Davydov1-18/+24
Page table pages are batched-freed in release_pages on most architectures. If we want to charge them to kmemcg (this is what is done later in this series), we need to teach mem_cgroup_uncharge_list to handle kmem pages. Link: http://lkml.kernel.org/r/18d5c09e97f80074ed25b97a7d0f32b95d875717.1464079538.git.vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26mm: memcontrol: cleanup kmem charge functionsVladimir Davydov1-20/+55
- Handle memcg_kmem_enabled check out to the caller. This reduces the number of function definitions making the code easier to follow. At the same time it doesn't result in code bloat, because all of these functions are used only in one or two places. - Move __GFP_ACCOUNT check to the caller as well so that one wouldn't have to dive deep into memcg implementation to see which allocations are charged and which are not. - Refresh comments. Link: http://lkml.kernel.org/r/52882a28b542c1979fd9a033b4dc8637fc347399.1464079537.git.vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26mm: oom: add memcg to oom_controlVladimir Davydov1-2/+3
It's a part of oom context just like allocation order and nodemask, so let's move it to oom_control instead of passing it in the argument list. Link: http://lkml.kernel.org/r/40e03fd7aaf1f55c75d787128d6d17c5a71226c2.1464358556.git.vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26mm/memcontrol.c: remove the useless parameter for mc_handle_swap_pteLi RongQing1-3/+3
It seems like this parameter has never been used since being introduced by 90254a65833b ("memcg: clean up move charge"). Not a big deal because I assume the function would get inlined into the caller anyway but why not get rid of it. [mhocko@suse.com: wrote changelog] Link: http://lkml.kernel.org/r/20160525151831.GJ20132@dhcp22.suse.cz Link: http://lkml.kernel.org/r/1464145026-26693-1-git-send-email-roy.qing.li@gmail.com Signed-off-by: Li RongQing <roy.qing.li@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-23mm: memcontrol: fix cgroup creation failure after many small jobsJohannes Weiner1-7/+75
The memory controller has quite a bit of state that usually outlives the cgroup and pins its CSS until said state disappears. At the same time it imposes a 16-bit limit on the CSS ID space to economically store IDs in the wild. Consequently, when we use cgroups to contain frequent but small and short-lived jobs that leave behind some page cache, we quickly run into the 64k limitations of outstanding CSSs. Creating a new cgroup fails with -ENOSPC while there are only a few, or even no user-visible cgroups in existence. Although pinning CSSs past cgroup removal is common, there are only two instances that actually need an ID after a cgroup is deleted: cache shadow entries and swapout records. Cache shadow entries reference the ID weakly and can deal with the CSS having disappeared when it's looked up later. They pose no hurdle. Swap-out records do need to pin the css to hierarchically attribute swapins after the cgroup has been deleted; though the only pages that remain swapped out after offlining are tmpfs/shmem pages. And those references are under the user's control, so they are manageable. This patch introduces a private 16-bit memcg ID and switches swap and cache shadow entries over to using that. This ID can then be recycled after offlining when the CSS remains pinned only by objects that don't specifically need it. This script demonstrates the problem by faulting one cache page in a new cgroup and deleting it again: set -e mkdir -p pages for x in `seq 128000`; do [ $((x % 1000)) -eq 0 ] && echo $x mkdir /cgroup/foo echo $$ >/cgroup/foo/cgroup.procs echo trex >pages/$x echo $$ >/cgroup/cgroup.procs rmdir /cgroup/foo done When run on an unpatched kernel, we eventually run out of possible IDs even though there are no visible cgroups: [root@ham ~]# ./cssidstress.sh [...] 65000 mkdir: cannot create directory '/cgroup/foo': No space left on device After this patch, the IDs get released upon cgroup destruction and the cache and css objects get released once memory reclaim kicks in. [hannes@cmpxchg.org: init the IDR] Link: http://lkml.kernel.org/r/20160621154601.GA22431@cmpxchg.org Fixes: b2052564e66d ("mm: memcontrol: continue cache reclaim from offlined groups") Link: http://lkml.kernel.org/r/20160617162516.GD19084@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: John Garcia <john.garcia@mesosphere.io> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Nikolay Borisov <kernel@kyup.com> Cc: <stable@vger.kernel.org> [3.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-24memcg: css_alloc should return an ERR_PTR value on errorTejun Heo1-1/+1
mem_cgroup_css_alloc() was returning NULL on failure while cgroup core expected it to return an ERR_PTR value leading to the following NULL deref after a css allocation failure. Fix it by return ERR_PTR(-ENOMEM) instead. I'll also update cgroup core so that it can handle NULL returns. mkdir: page allocation failure: order:6, mode:0x240c0c0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO) CPU: 0 PID: 8738 Comm: mkdir Not tainted 4.7.0-rc3+ #123 ... Call Trace: dump_stack+0x68/0xa1 warn_alloc_failed+0xd6/0x130 __alloc_pages_nodemask+0x4c6/0xf20 alloc_pages_current+0x66/0xe0 alloc_kmem_pages+0x14/0x80 kmalloc_order_trace+0x2a/0x1a0 __kmalloc+0x291/0x310 memcg_update_all_caches+0x6c/0x130 mem_cgroup_css_alloc+0x590/0x610 cgroup_apply_control_enable+0x18b/0x370 cgroup_mkdir+0x1de/0x2e0 kernfs_iop_mkdir+0x55/0x80 vfs_mkdir+0xb9/0x150 SyS_mkdir+0x66/0xd0 do_syscall_64+0x53/0x120 entry_SYSCALL64_slow_path+0x25/0x25 ... BUG: unable to handle kernel NULL pointer dereference at 00000000000000d0 IP: init_and_link_css+0x37/0x220 PGD 34b1e067 PUD 3a109067 PMD 0 Oops: 0002 [#1] SMP Modules linked in: CPU: 0 PID: 8738 Comm: mkdir Not tainted 4.7.0-rc3+ #123 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.2-20160422_131301-anatol 04/01/2014 task: ffff88007cbc5200 ti: ffff8800666d4000 task.ti: ffff8800666d4000 RIP: 0010:[<ffffffff810f2ca7>] [<ffffffff810f2ca7>] init_and_link_css+0x37/0x220 RSP: 0018:ffff8800666d7d90 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffffffff810f2499 RSI: 0000000000000000 RDI: 0000000000000008 RBP: ffff8800666d7db8 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88005a5fb400 R13: ffffffff81f0f8a0 R14: ffff88005a5fb400 R15: 0000000000000010 FS: 00007fc944689700(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3aed0d2b80 CR3: 000000003a1e8000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: cgroup_apply_control_enable+0x1ac/0x370 cgroup_mkdir+0x1de/0x2e0 kernfs_iop_mkdir+0x55/0x80 vfs_mkdir+0xb9/0x150 SyS_mkdir+0x66/0xd0 do_syscall_64+0x53/0x120 entry_SYSCALL64_slow_path+0x25/0x25 Code: 89 f5 48 89 fb 49 89 d4 48 83 ec 08 8b 05 72 3b d8 00 85 c0 0f 85 60 01 00 00 4c 89 e7 e8 72 f7 ff ff 48 8d 7b 08 48 89 d9 31 c0 <48> c7 83 d0 00 00 00 00 00 00 00 48 83 e7 f8 48 29 f9 81 c1 d8 RIP init_and_link_css+0x37/0x220 RSP <ffff8800666d7d90> CR2: 00000000000000d0 ---[ end trace a2d8836ae1e852d1 ]--- Link: http://lkml.kernel.org/r/20160621165740.GJ3262@mtj.duckdns.org Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-24memcg: mem_cgroup_migrate() may be called with irq disabledTejun Heo1-2/+3
mem_cgroup_migrate() uses local_irq_disable/enable() but can be called with irq disabled from migrate_page_copy(). This ends up enabling irq while holding a irq context lock triggering the following lockdep warning. Fix it by using irq_save/restore instead. ================================= [ INFO: inconsistent lock state ] 4.7.0-rc1+ #52 Tainted: G W --------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. kcompactd0/151 [HC0[0]:SC0[0]:HE1:SE1] takes: (&(&ctx->completion_lock)->rlock){+.?.-.}, at: [<000000000038fd96>] aio_migratepage+0x156/0x1e8 {IN-SOFTIRQ-W} state was registered at: __lock_acquire+0x5b6/0x1930 lock_acquire+0xee/0x270 _raw_spin_lock_irqsave+0x66/0xb0 aio_complete+0x98/0x328 dio_complete+0xe4/0x1e0 blk_update_request+0xd4/0x450 scsi_end_request+0x48/0x1c8 scsi_io_completion+0x272/0x698 blk_done_softirq+0xca/0xe8 __do_softirq+0xc8/0x518 irq_exit+0xee/0x110 do_IRQ+0x6a/0x88 io_int_handler+0x11a/0x25c __mutex_unlock_slowpath+0x144/0x1d8 __mutex_unlock_slowpath+0x140/0x1d8 kernfs_iop_permission+0x64/0x80 __inode_permission+0x9e/0xf0 link_path_walk+0x6e/0x510 path_lookupat+0xc4/0x1a8 filename_lookup+0x9c/0x160 user_path_at_empty+0x5c/0x70 SyS_readlinkat+0x68/0x140 system_call+0xd6/0x270 irq event stamp: 971410 hardirqs last enabled at (971409): migrate_page_move_mapping+0x3ea/0x588 hardirqs last disabled at (971410): _raw_spin_lock_irqsave+0x3c/0xb0 softirqs last enabled at (970526): __do_softirq+0x460/0x518 softirqs last disabled at (970519): irq_exit+0xee/0x110 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&ctx->completion_lock)->rlock); <Interrupt> lock(&(&ctx->completion_lock)->rlock); *** DEADLOCK *** 3 locks held by kcompactd0/151: #0: (&(&mapping->private_lock)->rlock){+.+.-.}, at: aio_migratepage+0x42/0x1e8 #1: (&ctx->ring_lock){+.+.+.}, at: aio_migratepage+0x5a/0x1e8 #2: (&(&ctx->completion_lock)->rlock){+.?.-.}, at: aio_migratepage+0x156/0x1e8 stack backtrace: CPU: 20 PID: 151 Comm: kcompactd0 Tainted: G W 4.7.0-rc1+ #52 Call Trace: show_trace+0xea/0xf0 show_stack+0x72/0xf0 dump_stack+0x9a/0xd8 print_usage_bug.part.27+0x2d4/0x2e8 mark_lock+0x17e/0x758 mark_held_locks+0xa2/0xd0 trace_hardirqs_on_caller+0x140/0x1c0 mem_cgroup_migrate+0x266/0x370 aio_migratepage+0x16a/0x1e8 move_to_new_page+0xb0/0x260 migrate_pages+0x8f4/0x9f0 compact_zone+0x4dc/0xdc8 kcompactd_do_work+0x1aa/0x358 kcompactd+0xba/0x2c8 kthread+0x10a/0x110 kernel_thread_starter+0x6/0xc kernel_thread_starter+0x0/0xc INFO: lockdep is turned off. Link: http://lkml.kernel.org/r/20160620184158.GO3262@mtj.duckdns.org Link: http://lkml.kernel.org/g/5767CFE5.7080904@de.ibm.com Fixes: 74485cf2bc85 ("mm: migrate: consolidate mem_cgroup_migrate() calls") Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: <stable@vger.kernel.org> [4.5+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-09revert "mm: memcontrol: fix possible css ref leak on oom"Andrew Morton1-1/+1
Revert commit 1383399d7be0 ("mm: memcontrol: fix possible css ref leak on oom"). Johannes points out "There is a task_in_memcg_oom() check before calling mem_cgroup_oom()". Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-03memcg: add RCU locking around css_for_each_descendant_pre() in memcg_offline_kmem()Tejun Heo1-0/+3
memcg_offline_kmem() may be called from memcg_free_kmem() after a css init failure. memcg_free_kmem() is a ->css_free callback which is called without cgroup_mutex and memcg_offline_kmem() ends up using css_for_each_descendant_pre() without any locking. Fix it by adding rcu read locking around it. mkdir: cannot create directory `65530': No space left on device =============================== [ INFO: suspicious RCU usage. ] 4.6.0-work+ #321 Not tainted ------------------------------- kernel/cgroup.c:4008 cgroup_mutex or RCU read lock required! [ 527.243970] other info that might help us debug this: [ 527.244715] rcu_scheduler_active = 1, debug_locks = 0 2 locks held by kworker/0:5/1664: #0: ("cgroup_destroy"){.+.+..}, at: [<ffffffff81060ab5>] process_one_work+0x165/0x4a0 #1: ((&css->destroy_work)#3){+.+...}, at: [<ffffffff81060ab5>] process_one_work+0x165/0x4a0 [ 527.248098] stack backtrace: CPU: 0 PID: 1664 Comm: kworker/0:5 Not tainted 4.6.0-work+ #321 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.1-1.fc24 04/01/2014 Workqueue: cgroup_destroy css_free_work_fn Call Trace: dump_stack+0x68/0xa1 lockdep_rcu_suspicious+0xd7/0x110 css_next_descendant_pre+0x7d/0xb0 memcg_offline_kmem.part.44+0x4a/0xc0 mem_cgroup_css_free+0x1ec/0x200 css_free_work_fn+0x49/0x5e0 process_one_work+0x1c5/0x4a0 worker_thread+0x49/0x490 kthread+0xea/0x100 ret_from_fork+0x1f/0x40 Link: http://lkml.kernel.org/r/20160526203018.GG23194@mtj.duckdns.org Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: <stable@vger.kernel.org> [4.5+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-27mm/memcontrol.c: move comments for get_mctgt_type() to proper positionLi RongQing1-18/+19
Move the comments for get_mctgt_type() to be before get_mctgt_type() implementation. Link: http://lkml.kernel.org/r/1463644638-7446-1-git-send-email-roy.qing.li@gmail.com Signed-off-by: Li RongQing <roy.qing.li@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-27mm/memcontrol.c: fix the margin computation in mem_cgroup_margin()Li RongQing1-0/+2
mem_cgroup_margin() might return (memory.limit - memory_count) when the memsw.limit is in excess. This doesn't happen usually because we do not allow excess on hard limits and (memory.limit <= memsw.limit), but __GFP_NOFAIL charges can force the charge and cause the excess when no memory is really swappable (swap is full or no anonymous memory is left). [mhocko@suse.com: rewrote changelog] Link: http://lkml.kernel.org/r/20160525155122.GK20132@dhcp22.suse.cz Link: http://lkml.kernel.org/r/1464068266-27736-1-git-send-email-roy.qing.li@gmail.com Signed-off-by: Li RongQing <roy.qing.li@gmail.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-26memcg: fix mem_cgroup_out_of_memory() return value.Tetsuo Handa1-0/+2
mem_cgroup_out_of_memory() is returning "true" if it finds a TIF_MEMDIE task after an eligible task was found, "false" if it found a TIF_MEMDIE task before an eligible task is found. This difference confuses memory_max_write() which checks the return value of mem_cgroup_out_of_memory(). Since memory_max_write() wants to continue looping, mem_cgroup_out_of_memory() should return "true" in this case. This patch sets a dummy pointer in order to return "true". Link: http://lkml.kernel.org/r/1463753327-5170-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-23mm: memcontrol: fix possible css ref leak on oomVladimir Davydov1-1/+1
mem_cgroup_oom may be invoked multiple times while a process is handling a page fault, in which case current->memcg_in_oom will be overwritten leaking the previously taken css reference. Link: http://lkml.kernel.org/r/1464019330-7579-1-git-send-email-vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20memcg: fix stale mem_cgroup_force_empty() commentGreg Thelen1-2/+1
Commit f61c42a7d911 ("memcg: remove tasks/children test from mem_cgroup_force_empty()") removed memory reparenting from the function. Fix the function's comment. Link: http://lkml.kernel.org/r/1462569810-54496-1-git-send-email-gthelen@google.com Signed-off-by: Greg Thelen <gthelen@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-19oom, oom_reaper: try to reap tasks which skip regular OOM killer pathMichal Hocko1-0/+1
If either the current task is already killed or PF_EXITING or a selected task is PF_EXITING then the oom killer is suppressed and so is the oom reaper. This patch adds try_oom_reaper which checks the given task and queues it for the oom reaper if that is safe to be done meaning that the task doesn't share the mm with an alive process. This might help to release the memory pressure while the task tries to exit. [akpm@linux-foundation.org: fix nommu build] Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Raushaniya Maksudova <rmaksudova@parallels.com> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-19mm: update_lru_size do the __mod_zone_page_stateHugh Dickins1-0/+2
Konstantin Khlebnikov pointed out (nearly four years ago, when lumpy reclaim was removed) that lru_size can be updated by -nr_taken once per call to isolate_lru_pages(), instead of page by page. Update it inside isolate_lru_pages(), or at its two callsites? I chose to update it at the callsites, rearranging and grouping the updates by nr_taken and nr_scanned together in both. With one exception, mem_cgroup_update_lru_size(,lru,) is then used where __mod_zone_page_state(,NR_LRU_BASE+lru,) is used; and we shall be adding some more calls in a future commit. Make the code a little smaller and simpler by incorporating stat update in lru_size update. The exception was move_active_pages_to_lru(), which aggregated the pgmoved stat update separately from the individual lru_size updates; but I still think this a simplification worth making. However, the __mod_zone_page_state is not peculiar to mem_cgroups: so better use the name update_lru_size, calls mem_cgroup_update_lru_size when CONFIG_MEMCG. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Yang Shi <yang.shi@linaro.org> Cc: Ning Qu <quning@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-19mm: update_lru_size warn and reset bad lru_sizeHugh Dickins1-4/+20
Though debug kernels have a VM_BUG_ON to help protect from misaccounting lru_size, non-debug kernels are liable to wrap it around: and then the vast unsigned long size draws page reclaim into a loop of repeatedly doing nothing on an empty list, without even a cond_resched(). That soft lockup looks confusingly like an over-busy reclaim scenario, with lots of contention on the lru_lock in shrink_inactive_list(): yet has a totally different origin. Help differentiate with a custom warning in mem_cgroup_update_lru_size(), even in non-debug kernels; and reset the size to avoid the lockup. But the particular bug which suggested this change was mine alone, and since fixed. Make it a WARN_ONCE: the first occurrence is the most informative, a flurry may follow, yet even when rate-limited little more is learnt. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Yang Shi <yang.shi@linaro.org> Cc: Ning Qu <quning@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-19mm/memcontrol.c:mem_cgroup_select_victim_node(): clarify commentMichal Hocko1-4/+3
> The comment seems to have not much to do with the code? I guess the comment tries to say that the code path is triggered when we charge the page which happens _before_ it is added to the LRU list and so last_scanned_node might contain the stale data. Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-19include/linux/nodemask.h: create next_node_in() helperAndrew Morton1-3/+1
Lots of code does node = next_node(node, XXX); if (node == MAX_NUMNODES) node = first_node(XXX); so create next_node_in() to do this and use it in various places. [mhocko@suse.com: use next_node_in() helper] Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@kernel.org> Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: David Rientjes <rientjes@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Laura Abbott <lauraa@codeaurora.org> Cc: Hui Zhu <zhuhui@xiaomi.com> Cc: Wang Xiaoqiang <wangxq10@lzu.edu.cn> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-25memcg: relocate charge moving from ->attach to ->post_attachTejun Heo1-18/+19
Hello, So, this ended up a lot simpler than I originally expected. I tested it lightly and it seems to work fine. Petr, can you please test these two patches w/o the lru drain drop patch and see whether the problem is gone? Thanks. ------ 8< ------ If charge moving is used, memcg performs relabeling of the affected pages from its ->attach callback which is called under both cgroup_threadgroup_rwsem and thus can't create new kthreads. This is fragile as various operations may depend on workqueues making forward progress which relies on the ability to create new kthreads. There's no reason to perform charge moving from ->attach which is deep in the task migration path. Move it to ->post_attach which is called after the actual migration is finished and cgroup_threadgroup_rwsem is dropped. * move_charge_struct->mm is added and ->can_attach is now responsible for pinning and recording the target mm. mem_cgroup_clear_mc() is updated accordingly. This also simplifies mem_cgroup_move_task(). * mem_cgroup_move_task() is now called from ->post_attach instead of ->attach. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@kernel.org> Debugged-and-tested-by: Petr Mladek <pmladek@suse.com> Reported-by: Cyril Hrubis <chrubis@suse.cz> Reported-by: Johannes Weiner <hannes@cmpxchg.org> Fixes: 1ed1328792ff ("sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem") Cc: <stable@vger.kernel.org> # 4.4+
2016-03-17mm: memcontrol: zap oom_info_lockVladimir Davydov1-4/+0
mem_cgroup_print_oom_info is always called under oom_lock, so oom_info_lock is redundant. Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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