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2016-09-15proc: revert /proc/<pid>/maps [stack:TID] annotationJohannes Weiner
[ Upstream commit 65376df582174ffcec9e6471bf5b0dd79ba05e4a ] Commit b76437579d13 ("procfs: mark thread stack correctly in proc/<pid>/maps") added [stack:TID] annotation to /proc/<pid>/maps. Finding the task of a stack VMA requires walking the entire thread list, turning this into quadratic behavior: a thousand threads means a thousand stacks, so the rendering of /proc/<pid>/maps needs to look at a million combinations. The cost is not in proportion to the usefulness as described in the patch. Drop the [stack:TID] annotation to make /proc/<pid>/maps (and /proc/<pid>/numa_maps) usable again for higher thread counts. The [stack] annotation inside /proc/<pid>/task/<tid>/maps is retained, as identifying the stack VMA there is an O(1) operation. Siddesh said: "The end users needed a way to identify thread stacks programmatically and there wasn't a way to do that. I'm afraid I no longer remember (or have access to the resources that would aid my memory since I changed employers) the details of their requirement. However, I did do this on my own time because I thought it was an interesting project for me and nobody really gave any feedback then as to its utility, so as far as I am concerned you could roll back the main thread maps information since the information is available in the thread-specific files" Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com> Cc: Shaohua Li <shli@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-09-07hugetlb: fix nr_pmds accounting with shared page tablesKirill A. Shutemov
commit c17b1f42594eb71b8d3eb5a6dfc907a7eb88a51d upstream. We account HugeTLB's shared page table to all processes who share it. The accounting happens during huge_pmd_share(). If somebody populates pud entry under us, we should decrease pagetable's refcount and decrease nr_pmds of the process. By mistake, I increase nr_pmds again in this case. :-/ It will lead to "BUG: non-zero nr_pmds on freeing mm: 2" on process' exit. Let's fix this by increasing nr_pmds only when we're sure that the page table will be used. Link: http://lkml.kernel.org/r/20160617122506.GC6534@node.shutemov.name Fixes: dc6c9a35b66b ("mm: account pmd page tables to the process") Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: zhongjiang <zhongjiang@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-20mm/hugetlb: avoid soft lockup in set_max_huge_pages()Jia He
commit 649920c6ab93429b94bc7c1aa7c0e8395351be32 upstream. In powerpc servers with large memory(32TB), we watched several soft lockups for hugepage under stress tests. The call traces are as follows: 1. get_page_from_freelist+0x2d8/0xd50 __alloc_pages_nodemask+0x180/0xc20 alloc_fresh_huge_page+0xb0/0x190 set_max_huge_pages+0x164/0x3b0 2. prep_new_huge_page+0x5c/0x100 alloc_fresh_huge_page+0xc8/0x190 set_max_huge_pages+0x164/0x3b0 This patch fixes such soft lockups. It is safe to call cond_resched() there because it is out of spin_lock/unlock section. Link: http://lkml.kernel.org/r/1469674442-14848-1-git-send-email-hejianet@gmail.com Signed-off-by: Jia He <hejianet@gmail.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-20block: fix bdi vs gendisk lifetime mismatchDan Williams
commit df08c32ce3be5be138c1dbfcba203314a3a7cd6f upstream. The name for a bdi of a gendisk is derived from the gendisk's devt. However, since the gendisk is destroyed before the bdi it leaves a window where a new gendisk could dynamically reuse the same devt while a bdi with the same name is still live. Arrange for the bdi to hold a reference against its "owner" disk device while it is registered. Otherwise we can hit sysfs duplicate name collisions like the following: WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80 sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1' Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015 0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351 0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8 Call Trace: [<ffffffff8134caec>] dump_stack+0x63/0x87 [<ffffffff8108c351>] __warn+0xd1/0xf0 [<ffffffff8108c3cf>] warn_slowpath_fmt+0x5f/0x80 [<ffffffff812a0d34>] sysfs_warn_dup+0x64/0x80 [<ffffffff812a0e1e>] sysfs_create_dir_ns+0x7e/0x90 [<ffffffff8134faaa>] kobject_add_internal+0xaa/0x320 [<ffffffff81358d4e>] ? vsnprintf+0x34e/0x4d0 [<ffffffff8134ff55>] kobject_add+0x75/0xd0 [<ffffffff816e66b2>] ? mutex_lock+0x12/0x2f [<ffffffff8148b0a5>] device_add+0x125/0x610 [<ffffffff8148b788>] device_create_groups_vargs+0xd8/0x100 [<ffffffff8148b7cc>] device_create_vargs+0x1c/0x20 [<ffffffff811b775c>] bdi_register+0x8c/0x180 [<ffffffff811b7877>] bdi_register_dev+0x27/0x30 [<ffffffff813317f5>] add_disk+0x175/0x4a0 Reported-by: Yi Zhang <yizhan@redhat.com> Tested-by: Yi Zhang <yizhan@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Fixed up missing 0 return in bdi_register_owner(). Signed-off-by: Jens Axboe <axboe@fb.com>
2016-08-16mm: memcontrol: fix memcg id ref counter on swap charge moveVladimir Davydov
commit 615d66c37c755c49ce022c9e5ac0875d27d2603d upstream. 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-16mm: memcontrol: fix swap counter leak on swapout from offline cgroupVladimir Davydov
commit 1f47b61fb4077936465dcde872a4e5cc4fe708da upstream. 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> Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-16mm: memcontrol: fix cgroup creation failure after many small jobsJohannes Weiner
commit 73f576c04b9410ed19660f74f97521bee6e1c546 upstream. 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-10mm, meminit: ensure node is online before checking whether pages are ↵Mel Gorman
uninitialised commit ef70b6f41cda6270165a6f27b2548ed31cfa3cb2 upstream. early_page_uninitialised looks up an arbitrary PFN. While a machine without node 0 will boot with "mm, page_alloc: Always return a valid node from early_pfn_to_nid", it works because it assumes that nodes are always in PFN order. This is not guaranteed so this patch adds robustness by always checking if the node being checked is online. Link: http://lkml.kernel.org/r/1468008031-3848-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-10mm, meminit: always return a valid node from early_pfn_to_nidMel Gorman
commit e4568d3803852d00effd41dcdd489e726b998879 upstream. early_pfn_to_nid can return node 0 if a PFN is invalid on machines that has no node 0. A machine with only node 1 was observed to crash with the following message: BUG: unable to handle kernel paging request at 000000000002a3c8 PGD 0 Modules linked in: Hardware name: Supermicro H8DSP-8/H8DSP-8, BIOS 080011 06/30/2006 task: ffffffff81c0d500 ti: ffffffff81c00000 task.ti: ffffffff81c00000 RIP: reserve_bootmem_region+0x6a/0xef CR2: 000000000002a3c8 CR3: 0000000001c06000 CR4: 00000000000006b0 Call Trace: free_all_bootmem+0x4b/0x12a mem_init+0x70/0xa3 start_kernel+0x25b/0x49b The problem is that early_page_uninitialised uses the early_pfn_to_nid helper which returns node 0 for invalid PFNs. No caller of early_pfn_to_nid cares except early_page_uninitialised. This patch has early_pfn_to_nid always return a valid node. Link: http://lkml.kernel.org/r/1468008031-3848-3-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-10mm, compaction: prevent VM_BUG_ON when terminating freeing scannerDavid Rientjes
commit a46cbf3bc53b6a93fb84a5ffb288c354fa807954 upstream. It's possible to isolate some freepages in a pageblock and then fail split_free_page() due to the low watermark check. In this case, we hit VM_BUG_ON() because the freeing scanner terminated early without a contended lock or enough freepages. This should never have been a VM_BUG_ON() since it's not a fatal condition. It should have been a VM_WARN_ON() at best, or even handled gracefully. Regardless, we need to terminate anytime the full pageblock scan was not done. The logic belongs in isolate_freepages_block(), so handle its state gracefully by terminating the pageblock loop and making a note to restart at the same pageblock next time since it was not possible to complete the scan this time. [rientjes@google.com: don't rescan pages in a pageblock] Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1607111244150.83138@chino.kir.corp.google.com Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1606291436300.145590@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Reported-by: Minchan Kim <minchan@kernel.org> Tested-by: Minchan Kim <minchan@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-10mm, compaction: abort free scanner if split failsDavid Rientjes
commit a4f04f2c6955aff5e2c08dcb40aca247ff4d7370 upstream. If the memory compaction free scanner cannot successfully split a free page (only possible due to per-zone low watermark), terminate the free scanner rather than continuing to scan memory needlessly. If the watermark is insufficient for a free page of order <= cc->order, then terminate the scanner since all future splits will also likely fail. This prevents the compaction freeing scanner from scanning all memory on very large zones (very noticeable for zones > 128GB, for instance) when all splits will likely fail while holding zone->lock. compaction_alloc() iterating a 128GB zone has been benchmarked to take over 400ms on some systems whereas any free page isolated and ready to be split ends up failing in split_free_page() because of the low watermark check and thus the iteration continues. The next time compaction occurs, the freeing scanner will likely start at the end of the zone again since no success was made previously and we get the same lengthy iteration until the zone is brought above the low watermark. All thp page faults can take >400ms in such a state without this fix. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1606211820350.97086@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-10mm, sl[au]b: add __GFP_ATOMIC to the GFP reclaim maskMel Gorman
commit e838a45f9392a5bd2be1cd3ab0b16ae85857461c upstream. Commit d0164adc89f6 ("mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd") modified __GFP_WAIT to explicitly identify the difference between atomic callers and those that were unwilling to sleep. Later the definition was removed entirely. The GFP_RECLAIM_MASK is the set of flags that affect watermark checking and reclaim behaviour but __GFP_ATOMIC was never added. Without it, atomic users of the slab allocator strip the __GFP_ATOMIC flag and cannot access the page allocator atomic reserves. This patch addresses the problem. The user-visible impact depends on the workload but potentially atomic allocations unnecessarily fail without this path. Link: http://lkml.kernel.org/r/20160610093832.GK2527@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reported-by: Marcin Wojtas <mw@semihalf.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-27tmpfs: fix regression hang in fallocate undoHugh Dickins
commit 7f556567036cb7f89aabe2f0954b08566b4efb53 upstream. The well-spotted fallocate undo fix is good in most cases, but not when fallocate failed on the very first page. index 0 then passes lend -1 to shmem_undo_range(), and that has two bad effects: (a) that it will undo every fallocation throughout the file, unrestricted by the current range; but more importantly (b) it can cause the undo to hang, because lend -1 is treated as truncation, which makes it keep on retrying until every page has gone, but those already fully instantiated will never go away. Big thank you to xfstests generic/269 which demonstrates this. Fixes: b9b4bb26af01 ("tmpfs: don't undo fallocate past its last page") Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-27tmpfs: don't undo fallocate past its last pageAnthony Romano
commit b9b4bb26af017dbe930cd4df7f9b2fc3a0497bfe upstream. When fallocate is interrupted it will undo a range that extends one byte past its range of allocated pages. This can corrupt an in-use page by zeroing out its first byte. Instead, undo using the inclusive byte range. Fixes: 1635f6a74152f1d ("tmpfs: undo fallocation on failure") Link: http://lkml.kernel.org/r/1462713387-16724-1-git-send-email-anthony.romano@coreos.com Signed-off-by: Anthony Romano <anthony.romano@coreos.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Brandon Philips <brandon@ifup.co> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-27percpu: fix synchronization between synchronous map extension and chunk ↵Tejun Heo
destruction commit 6710e594f71ccaad8101bc64321152af7cd9ea28 upstream. For non-atomic allocations, pcpu_alloc() can try to extend the area map synchronously after dropping pcpu_lock; however, the extension wasn't synchronized against chunk destruction and the chunk might get freed while extension is in progress. This patch fixes the bug by putting most of non-atomic allocations under pcpu_alloc_mutex to synchronize against pcpu_balance_work which is responsible for async chunk management including destruction. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Reported-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Sasha Levin <sasha.levin@oracle.com> Fixes: 1a4d76076cda ("percpu: implement asynchronous chunk population") Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-27percpu: fix synchronization between chunk->map_extend_work and chunk destructionTejun Heo
commit 4f996e234dad488e5d9ba0858bc1bae12eff82c3 upstream. Atomic allocations can trigger async map extensions which is serviced by chunk->map_extend_work. pcpu_balance_work which is responsible for destroying idle chunks wasn't synchronizing properly against chunk->map_extend_work and may end up freeing the chunk while the work item is still in flight. This patch fixes the bug by rolling async map extension operations into pcpu_balance_work. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Reported-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Sasha Levin <sasha.levin@oracle.com> Fixes: 9c824b6a172c ("percpu: make sure chunk->map array has available space") Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-27mm: Export migrate_page_move_mapping and migrate_page_copyRichard Weinberger
commit 1118dce773d84f39ebd51a9fe7261f9169cb056e upstream. Export these symbols such that UBIFS can implement ->migratepage. Signed-off-by: Richard Weinberger <richard@nod.at> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-27writeback: use higher precision calculation in domain_dirty_limits()Tejun Heo
commit 62a584fe05eef1f80ed49a286a29328f1a224fb9 upstream. As vm.dirty_[background_]bytes can't be applied verbatim to multiple cgroup writeback domains, they get converted to percentages in domain_dirty_limits() and applied the same way as vm.dirty_[background]ratio. However, if the specified bytes is lower than 1% of available memory, the calculated ratios become zero and the writeback domain gets throttled constantly. Fix it by using per-PAGE_SIZE instead of percentage for ratio calculations. Also, the updated DIV_ROUND_UP() usages now should yield 1/4096 (0.0244%) as the minimum ratio as long as the specified bytes are above zero. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Miao Xie <miaoxie@huawei.com> Link: http://lkml.kernel.org/g/57333E75.3080309@huawei.com Fixes: 9fc3a43e1757 ("writeback: separate out domain_dirty_limits()") Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Adjusted comment based on Jan's suggestion. Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-24memcg: add RCU locking around css_for_each_descendant_pre() in ↵Tejun Heo
memcg_offline_kmem() commit 3a06bb78ceeceacc86a1e31133a7944013f9775b upstream. 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-06-07mm: use phys_addr_t for reserve_bootmem_region() argumentsStefan Bader
commit 4b50bcc7eda4d3cc9e3f2a0aa60e590fedf728c5 upstream. Since commit 92923ca3aace ("mm: meminit: only set page reserved in the memblock region") the reserved bit is set on reserved memblock regions. However start and end address are passed as unsigned long. This is only 32bit on i386, so it can end up marking the wrong pages reserved for ranges at 4GB and above. This was observed on a 32bit Xen dom0 which was booted with initial memory set to a value below 4G but allowing to balloon in memory (dom0_mem=1024M for example). This would define a reserved bootmem region for the additional memory (for example on a 8GB system there was a reverved region covering the 4GB-8GB range). But since the addresses were passed on as unsigned long, this was actually marking all pages from 0 to 4GB as reserved. Fixes: 92923ca3aacef63 ("mm: meminit: only set page reserved in the memblock region") Link: http://lkml.kernel.org/r/1463491221-10573-1-git-send-email-stefan.bader@canonical.com Signed-off-by: Stefan Bader <stefan.bader@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-18zsmalloc: fix zs_can_compact() integer overflowSergey Senozhatsky
commit 44f43e99fe70833058482d183e99fdfd11220996 upstream. zs_can_compact() has two race conditions in its core calculation: unsigned long obj_wasted = zs_stat_get(class, OBJ_ALLOCATED) - zs_stat_get(class, OBJ_USED); 1) classes are not locked, so the numbers of allocated and used objects can change by the concurrent ops happening on other CPUs 2) shrinker invokes it from preemptible context Depending on the circumstances, thus, OBJ_ALLOCATED can become less than OBJ_USED, which can result in either very high or negative `total_scan' value calculated later in do_shrink_slab(). do_shrink_slab() has some logic to prevent those cases: vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-64 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62 However, due to the way `total_scan' is calculated, not every shrinker->count_objects() overflow can be spotted and handled. To demonstrate the latter, I added some debugging code to do_shrink_slab() (x86_64) and the results were: vmscan: OVERFLOW: shrinker->count_objects() == -1 [18446744073709551615] vmscan: but total_scan > 0: 92679974445502 vmscan: resulting total_scan: 92679974445502 [..] vmscan: OVERFLOW: shrinker->count_objects() == -1 [18446744073709551615] vmscan: but total_scan > 0: 22634041808232578 vmscan: resulting total_scan: 22634041808232578 Even though shrinker->count_objects() has returned an overflowed value, the resulting `total_scan' is positive, and, what is more worrisome, it is insanely huge. This value is getting used later on in shrinker->scan_objects() loop: while (total_scan >= batch_size || total_scan >= freeable) { unsigned long ret; unsigned long nr_to_scan = min(batch_size, total_scan); shrinkctl->nr_to_scan = nr_to_scan; ret = shrinker->scan_objects(shrinker, shrinkctl); if (ret == SHRINK_STOP) break; freed += ret; count_vm_events(SLABS_SCANNED, nr_to_scan); total_scan -= nr_to_scan; cond_resched(); } `total_scan >= batch_size' is true for a very-very long time and 'total_scan >= freeable' is also true for quite some time, because `freeable < 0' and `total_scan' is large enough, for example, 22634041808232578. The only break condition, in the given scheme of things, is shrinker->scan_objects() == SHRINK_STOP test, which is a bit too weak to rely on, especially in heavy zsmalloc-usage scenarios. To fix the issue, take a pool stat snapshot and use it instead of racy zs_stat_get() calls. Link: http://lkml.kernel.org/r/20160509140052.3389-1-sergey.senozhatsky@gmail.com Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-11writeback: Fix performance regression in wb_over_bg_thresh()Howard Cochran
commit 74d369443325063a5f0260e63971decb950fd8fa upstream. Commit 947e9762a8dd ("writeback: update wb_over_bg_thresh() to use wb_domain aware operations") unintentionally changed this function's meaning from "are there more dirty pages than the background writeback threshold" to "are there more dirty pages than the writeback threshold". The background writeback threshold is typically half of the writeback threshold, so this had the effect of raising the number of dirty pages required to cause a writeback worker to perform background writeout. This can cause a very severe performance regression when a BDI uses BDI_CAP_STRICTLIMIT because balance_dirty_pages() and the writeback worker can now disagree on whether writeback should be initiated. For example, in a system having 1GB of RAM, a single spinning disk, and a "pass-through" FUSE filesystem mounted over the disk, application code mmapped a 128MB file on the disk and was randomly dirtying pages in that mapping. Because FUSE uses strictlimit and has a default max_ratio of only 1%, in balance_dirty_pages, thresh is ~200, bg_thresh is ~100, and the dirty_freerun_ceiling is the average of those, ~150. So, it pauses the dirtying processes when we have 151 dirty pages and wakes up a background writeback worker. But the worker tests the wrong threshold (200 instead of 100), so it does not initiate writeback and just returns. Thus, balance_dirty_pages keeps looping, sleeping and then waking up the worker who will do nothing. It remains stuck in this state until the few dirty pages that we have finally expire and we write them back for that reason. Then the whole process repeats, resulting in near-zero throughput through the FUSE BDI. The fix is to call the parameterized variant of wb_calc_thresh, so that the worker will do writeback if the bg_thresh is exceeded which was the behavior before the referenced commit. Fixes: 947e9762a8dd ("writeback: update wb_over_bg_thresh() to use wb_domain aware operations") Signed-off-by: Howard Cochran <hcochran@kernelspring.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Tested-by Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-11mm: update min_free_kbytes from khugepaged after core initializationJason Baron
commit bc22af74f271ef76b2e6f72f3941f91f0da3f5f8 upstream. Khugepaged attempts to raise min_free_kbytes if its set too low. However, on boot khugepaged sets min_free_kbytes first from subsys_initcall(), and then the mm 'core' over-rides min_free_kbytes after from init_per_zone_wmark_min(), via a module_init() call. Khugepaged used to use a late_initcall() to set min_free_kbytes (such that it occurred after the core initialization), however this was removed when the initialization of min_free_kbytes was integrated into the starting of the khugepaged thread. The fix here is simply to invoke the core initialization using a core_initcall() instead of module_init(), such that the previous initialization ordering is restored. I didn't restore the late_initcall() since start_stop_khugepaged() already sets min_free_kbytes via set_recommended_min_free_kbytes(). This was noticed when we had a number of page allocation failures when moving a workload to a kernel with this new initialization ordering. On an 8GB system this restores min_free_kbytes back to 67584 from 11365 when CONFIG_TRANSPARENT_HUGEPAGE=y is set and either CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y or CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y. Fixes: 79553da293d3 ("thp: cleanup khugepaged startup") Signed-off-by: Jason Baron <jbaron@akamai.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-11mm/zswap: provide unique zpool nameDan Streetman
commit 32a4e169039927bfb6ee9f0ccbbe3a8aaf13a4bc upstream. Instead of using "zswap" as the name for all zpools created, add an atomic counter and use "zswap%x" with the counter number for each zpool created, to provide a unique name for each new zpool. As zsmalloc, one of the zpool implementations, requires/expects a unique name for each pool created, zswap should provide a unique name. The zsmalloc pool creation does not fail if a new pool with a conflicting name is created, unless CONFIG_ZSMALLOC_STAT is enabled; in that case, zsmalloc pool creation fails with -ENOMEM. Then zswap will be unable to change its compressor parameter if its zpool is zsmalloc; it also will be unable to change its zpool parameter back to zsmalloc, if it has any existing old zpool using zsmalloc with page(s) in it. Attempts to change the parameters will result in failure to create the zpool. This changes zswap to provide a unique name for each zpool creation. Fixes: f1c54846ee45 ("zswap: dynamic pool creation") Signed-off-by: Dan Streetman <ddstreet@ieee.org> Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Dan Streetman <dan.streetman@canonical.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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-11mm, cma: prevent nr_isolated_* counters from going negativeHugh Dickins
commit 14af4a5e9b26ad251f81c174e8a43f3e179434a5 upstream. /proc/sys/vm/stat_refresh warns nr_isolated_anon and nr_isolated_file go increasingly negative under compaction: which would add delay when should be none, or no delay when should delay. The bug in compaction was due to a recent mmotm patch, but much older instance of the bug was also noticed in isolate_migratepages_range() which is used for CMA and gigantic hugepage allocations. The bug is caused by putback_movable_pages() in an error path decrementing the isolated counters without them being previously incremented by acct_isolated(). Fix isolate_migratepages_range() by removing the error-path putback, thus reaching acct_isolated() with migratepages still isolated, and leaving putback to caller like most other places do. Fixes: edc2ca612496 ("mm, compaction: move pageblock checks up from isolate_migratepages_range()") [vbabka@suse.cz: expanded the changelog] Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-04mm/hwpoison: fix wrong num_poisoned_pages accountingMinchan Kim
commit d7e69488bd04de165667f6bc741c1c0ec6042ab9 upstream. Currently, migration code increses num_poisoned_pages on *failed* migration page as well as successfully migrated one at the trial of memory-failure. It will make the stat wrong. As well, it marks the page as PG_HWPoison even if the migration trial failed. It would mean we cannot recover the corrupted page using memory-failure facility. This patches fixes it. Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-04mm: vmscan: reclaim highmem zone if buffer_heads is over limitMinchan Kim
commit 7bf52fb891b64b8d61caf0b82060adb9db761aec upstream. We have been reclaimed highmem zone if buffer_heads is over limit but commit 6b4f7799c6a5 ("mm: vmscan: invoke slab shrinkers from shrink_zone()") changed the behavior so it doesn't reclaim highmem zone although buffer_heads is over the limit. This patch restores the logic. Fixes: 6b4f7799c6a5 ("mm: vmscan: invoke slab shrinkers from shrink_zone()") Signed-off-by: Minchan Kim <minchan@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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-04numa: fix /proc/<pid>/numa_maps for THPGerald Schaefer
commit 28093f9f34cedeaea0f481c58446d9dac6dd620f upstream. In gather_pte_stats() a THP pmd is cast into a pte, which is wrong because the layouts may differ depending on the architecture. On s390 this will lead to inaccurate numa_maps accounting in /proc because of misguided pte_present() and pte_dirty() checks on the fake pte. On other architectures pte_present() and pte_dirty() may work by chance, but there may be an issue with direct-access (dax) mappings w/o underlying struct pages when HAVE_PTE_SPECIAL is set and THP is available. In vm_normal_page() the fake pte will be checked with pte_special() and because there is no "special" bit in a pmd, this will always return false and the VM_PFNMAP | VM_MIXEDMAP checking will be skipped. On dax mappings w/o struct pages, an invalid struct page pointer would then be returned that can crash the kernel. This patch fixes the numa_maps THP handling by introducing new "_pmd" variants of the can_gather_numa_stats() and vm_normal_page() functions. Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-04mm/huge_memory: replace VM_NO_THP VM_BUG_ON with actual VMA checkKonstantin Khlebnikov
commit 3486b85a29c1741db99d0c522211c82d2b7a56d0 upstream. Khugepaged detects own VMAs by checking vm_file and vm_ops but this way it cannot distinguish private /dev/zero mappings from other special mappings like /dev/hpet which has no vm_ops and popultes PTEs in mmap. This fixes false-positive VM_BUG_ON and prevents installing THP where they are not expected. Link: http://lkml.kernel.org/r/CACT4Y+ZmuZMV5CjSFOeXviwQdABAgT7T+StKfTqan9YDtgEi5g@mail.gmail.com Fixes: 78f11a255749 ("mm: thp: fix /dev/zero MAP_PRIVATE and vm_flags cleanups") Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-04memcg: relocate charge moving from ->attach to ->post_attachTejun Heo
commit 264a0ae164bc0e9144bebcd25ff030d067b1a878 upstream. 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") Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-04slub: clean up code for kmem cgroup support to kmem_cache_free_bulkJesper Dangaard Brouer
commit 376bf125ac781d32e202760ed7deb1ae4ed35d31 upstream. This change is primarily an attempt to make it easier to realize the optimizations the compiler performs in-case CONFIG_MEMCG_KMEM is not enabled. Performance wise, even when CONFIG_MEMCG_KMEM is compiled in, the overhead is zero. This is because, as long as no process have enabled kmem cgroups accounting, the assignment is replaced by asm-NOP operations. This is possible because memcg_kmem_enabled() uses a static_key_false() construct. It also helps readability as it avoid accessing the p[] array like: p[size - 1] which "expose" that the array is processed backwards inside helper function build_detached_freelist(). Lastly this also makes the code more robust, in error case like passing NULL pointers in the array. Which were previously handled before commit 033745189b1b ("slub: add missing kmem cgroup support to kmem_cache_free_bulk"). Fixes: 033745189b1b ("slub: add missing kmem cgroup support to kmem_cache_free_bulk") 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> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-20mm: fix invalid node in alloc_migrate_target()Xishi Qiu
commit 6f25a14a7053b69917e2ebea0d31dd444cd31fd5 upstream. It is incorrect to use next_node to find a target node, it will return MAX_NUMNODES or invalid node. This will lead to crash in buddy system allocation. Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage") Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: David Rientjes <rientjes@google.com> Cc: "Laura Abbott" <lauraa@codeaurora.org> Cc: Hui Zhu <zhuhui@xiaomi.com> Cc: Wang Xiaoqiang <wangxq10@lzu.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-12mm/page_alloc: prevent merging between isolated and other pageblocksVlastimil Babka
commit d9dddbf556674bf125ecd925b24e43a5cf2a568a upstream. Hanjun Guo has reported that a CMA stress test causes broken accounting of CMA and free pages: > Before the test, I got: > -bash-4.3# cat /proc/meminfo | grep Cma > CmaTotal: 204800 kB > CmaFree: 195044 kB > > > After running the test: > -bash-4.3# cat /proc/meminfo | grep Cma > CmaTotal: 204800 kB > CmaFree: 6602584 kB > > So the freed CMA memory is more than total.. > > Also the the MemFree is more than mem total: > > -bash-4.3# cat /proc/meminfo > MemTotal: 16342016 kB > MemFree: 22367268 kB > MemAvailable: 22370528 kB Laura Abbott has confirmed the issue and suspected the freepage accounting rewrite around 3.18/4.0 by Joonsoo Kim. Joonsoo had a theory that this is caused by unexpected merging between MIGRATE_ISOLATE and MIGRATE_CMA pageblocks: > CMA isolates MAX_ORDER aligned blocks, but, during the process, > partialy isolated block exists. If MAX_ORDER is 11 and > pageblock_order is 9, two pageblocks make up MAX_ORDER > aligned block and I can think following scenario because pageblock > (un)isolation would be done one by one. > > (each character means one pageblock. 'C', 'I' means MIGRATE_CMA, > MIGRATE_ISOLATE, respectively. > > CC -> IC -> II (Isolation) > II -> CI -> CC (Un-isolation) > > If some pages are freed at this intermediate state such as IC or CI, > that page could be merged to the other page that is resident on > different type of pageblock and it will cause wrong freepage count. This was supposed to be prevented by CMA operating on MAX_ORDER blocks, but since it doesn't hold the zone->lock between pageblocks, a race window does exist. It's also likely that unexpected merging can occur between MIGRATE_ISOLATE and non-CMA pageblocks. This should be prevented in __free_one_page() since commit 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock"). However, we only check the migratetype of the pageblock where buddy merging has been initiated, not the migratetype of the buddy pageblock (or group of pageblocks) which can be MIGRATE_ISOLATE. Joonsoo has suggested checking for buddy migratetype as part of page_is_buddy(), but that would add extra checks in allocator hotpath and bloat-o-meter has shown significant code bloat (the function is inline). This patch reduces the bloat at some expense of more complicated code. The buddy-merging while-loop in __free_one_page() is initially bounded to pageblock_border and without any migratetype checks. The checks are placed outside, bumping the max_order if merging is allowed, and returning to the while-loop with a statement which can't be possibly considered harmful. This fixes the accounting bug and also removes the arguably weird state in the original commit 3c605096d315 where buddies could be left unmerged. Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock") Link: https://lkml.org/lkml/2016/3/2/280 Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Hanjun Guo <guohanjun@huawei.com> Tested-by: Hanjun Guo <guohanjun@huawei.com> Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Debugged-by: Laura Abbott <labbott@redhat.com> Debugged-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-12mm: memcontrol: reclaim and OOM kill when shrinking memory.max below usageJohannes Weiner
commit b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f upstream. Setting the original memory.limit_in_bytes hardlimit is subject to a race condition when the desired value is below the current usage. The code tries a few times to first reclaim and then see if the usage has dropped to where we would like it to be, but there is no locking, and the workload is free to continue making new charges up to the old limit. Thus, attempting to shrink a workload relies on pure luck and hope that the workload happens to cooperate. To fix this in the cgroup2 memory.max knob, do it the other way round: set the limit first, then try enforcement. And if reclaim is not able to succeed, trigger OOM kills in the group. Keep going until the new limit is met, we run out of OOM victims and there's only unreclaimable memory left, or the task writing to memory.max is killed. This allows users to shrink groups reliably, and the behavior is consistent with what happens when new charges are attempted in excess of memory.max. Signed-off-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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-12mm: memcontrol: reclaim when shrinking memory.high below usageJohannes Weiner
commit 588083bb37a3cea8533c392370a554417c8f29cb upstream. When setting memory.high below usage, nothing happens until the next charge comes along, and then it will only reclaim its own charge and not the now potentially huge excess of the new memory.high. This can cause groups to stay in excess of their memory.high indefinitely. To fix that, when shrinking memory.high, kick off a reclaim cycle that goes after the delta. Signed-off-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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-03-03make sure that freeing shmem fast symlinks is RCU-delayedAl Viro
commit 3ed47db34f480df7caf44436e3e63e555351ae9a upstream. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-03-03virtio_balloon: fix race between migration and ballooningMinchan Kim
commit 21ea9fb69e7c4b1b1559c3e410943d3ff248ffcb upstream. In balloon_page_dequeue, pages_lock should cover the loop (ie, list_for_each_entry_safe). Otherwise, the cursor page could be isolated by compaction and then list_del by isolation could poison the page->lru.{prev,next} so the loop finally could access wrong address like this. This patch fixes the bug. general protection fault: 0000 [#1] SMP Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 2 PID: 82 Comm: vballoon Not tainted 4.4.0-rc5-mm1-access_bit+ #1906 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff8800a7ff0000 ti: ffff8800a7fec000 task.ti: ffff8800a7fec000 RIP: 0010:[<ffffffff8115e754>] [<ffffffff8115e754>] balloon_page_dequeue+0x54/0x130 RSP: 0018:ffff8800a7fefdc0 EFLAGS: 00010246 RAX: ffff88013fff9a70 RBX: ffffea000056fe00 RCX: 0000000000002b7d RDX: ffff88013fff9a70 RSI: ffffea000056fe00 RDI: ffff88013fff9a68 RBP: ffff8800a7fefde8 R08: ffffea000056fda0 R09: 0000000000000000 R10: ffff8800a7fefd90 R11: 0000000000000001 R12: dead0000000000e0 R13: ffffea000056fe20 R14: ffff880138809070 R15: ffff880138809060 FS: 0000000000000000(0000) GS:ffff88013fc40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007f229c10e000 CR3: 00000000b8b53000 CR4: 00000000000006a0 Stack: 0000000000000100 ffff880138809088 ffff880138809000 ffff880138809060 0000000000000046 ffff8800a7fefe28 ffffffff812c86d3 ffff880138809020 ffff880138809000 fffffffffff91900 0000000000000100 ffff880138809060 Call Trace: [<ffffffff812c86d3>] leak_balloon+0x93/0x1a0 [<ffffffff812c8bc7>] balloon+0x217/0x2a0 [<ffffffff8143739e>] ? __schedule+0x31e/0x8b0 [<ffffffff81078160>] ? abort_exclusive_wait+0xb0/0xb0 [<ffffffff812c89b0>] ? update_balloon_stats+0xf0/0xf0 [<ffffffff8105b6e9>] kthread+0xc9/0xe0 [<ffffffff8105b620>] ? kthread_park+0x60/0x60 [<ffffffff8143b4af>] ret_from_fork+0x3f/0x70 [<ffffffff8105b620>] ? kthread_park+0x60/0x60 Code: 8d 60 e0 0f 84 af 00 00 00 48 8b 43 20 a8 01 75 3b 48 89 d8 f0 0f ba 28 00 72 10 48 8b 03 f6 c4 08 75 2f 48 89 df e8 8c 83 f9 ff <49> 8b 44 24 20 4d 8d 6c 24 20 48 83 e8 20 4d 39 f5 74 7a 4c 89 RIP [<ffffffff8115e754>] balloon_page_dequeue+0x54/0x130 RSP <ffff8800a7fefdc0> ---[ end trace 43cf28060d708d5f ]--- Kernel panic - not syncing: Fatal exception Dumping ftrace buffer: (ftrace buffer empty) Kernel Offset: disabled Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-03-03mm: numa: quickly fail allocations for NUMA balancing on full nodesMel Gorman
commit 8479eba7781fa9ffb28268840de6facfc12c35a7 upstream. Commit 4167e9b2cf10 ("mm: remove GFP_THISNODE") removed the GFP_THISNODE flag combination due to confusing semantics. It noted that alloc_misplaced_dst_page() was one such user after changes made by commit e97ca8e5b864 ("mm: fix GFP_THISNODE callers and clarify"). Unfortunately when GFP_THISNODE was removed, users of alloc_misplaced_dst_page() started waking kswapd and entering direct reclaim because the wrong GFP flags are cleared. The consequence is that workloads that used to fit into memory now get reclaimed which is addressed by this patch. The problem can be demonstrated with "mutilate" that exercises memcached which is software dedicated to memory object caching. The configuration uses 80% of memory and is run 3 times for varying numbers of clients. The results on a 4-socket NUMA box are mutilate 4.4.0 4.4.0 vanilla numaswap-v1 Hmean 1 8394.71 ( 0.00%) 8395.32 ( 0.01%) Hmean 4 30024.62 ( 0.00%) 34513.54 ( 14.95%) Hmean 7 32821.08 ( 0.00%) 70542.96 (114.93%) Hmean 12 55229.67 ( 0.00%) 93866.34 ( 69.96%) Hmean 21 39438.96 ( 0.00%) 85749.21 (117.42%) Hmean 30 37796.10 ( 0.00%) 50231.49 ( 32.90%) Hmean 47 18070.91 ( 0.00%) 38530.13 (113.22%) The metric is queries/second with the more the better. The results are way outside of the noise and the reason for the improvement is obvious from some of the vmstats 4.4.0 4.4.0 vanillanumaswap-v1r1 Minor Faults 1929399272 2146148218 Major Faults 19746529 3567 Swap Ins 57307366 9913 Swap Outs 50623229 17094 Allocation stalls 35909 443 DMA allocs 0 0 DMA32 allocs 72976349 170567396 Normal allocs 5306640898 5310651252 Movable allocs 0 0 Direct pages scanned 404130893 799577 Kswapd pages scanned 160230174 0 Kswapd pages reclaimed 55928786 0 Direct pages reclaimed 1843936 41921 Page writes file 2391 0 Page writes anon 50623229 17094 The vanilla kernel is swapping like crazy with large amounts of direct reclaim and kswapd activity. The figures are aggregate but it's known that the bad activity is throughout the entire test. Note that simple streaming anon/file memory consumers also see this problem but it's not as obvious. In those cases, kswapd is awake when it should not be. As there are at least two reclaim-related bugs out there, it's worth spelling out the user-visible impact. This patch only addresses bugs related to excessive reclaim on NUMA hardware when the working set is larger than a NUMA node. There is a bug related to high kswapd CPU usage but the reports are against laptops and other UMA hardware and is not addressed by this patch. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-03-03mm: thp: fix SMP race condition between THP page fault and MADV_DONTNEEDAndrea Arcangeli
commit ad33bb04b2a6cee6c1f99fabb15cddbf93ff0433 upstream. pmd_trans_unstable()/pmd_none_or_trans_huge_or_clear_bad() were introduced to locklessy (but atomically) detect when a pmd is a regular (stable) pmd or when the pmd is unstable and can infinitely transition from pmd_none() and pmd_trans_huge() from under us, while only holding the mmap_sem for reading (for writing not). While holding the mmap_sem only for reading, MADV_DONTNEED can run from under us and so before we can assume the pmd to be a regular stable pmd we need to compare it against pmd_none() and pmd_trans_huge() in an atomic way, with pmd_trans_unstable(). The old pmd_trans_huge() left a tiny window for a race. Useful applications are unlikely to notice the difference as doing MADV_DONTNEED concurrently with a page fault would lead to undefined behavior. [akpm@linux-foundation.org: tidy up comment grammar/layout] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-25mm,thp: khugepaged: call pte flush at the time of collapseVineet Gupta
commit 6a6ac72fd6ea32594b316513e1826c3f6db4cc93 upstream. This showed up on ARC when running LMBench bw_mem tests as Overlapping TLB Machine Check Exception triggered due to STLB entry (2M pages) overlapping some NTLB entry (regular 8K page). bw_mem 2m touches a large chunk of vaddr creating NTLB entries. In the interim khugepaged kicks in, collapsing the contiguous ptes into a single pmd. pmdp_collapse_flush()->flush_pmd_tlb_range() is called to flush out NTLB entries for the ptes. This for ARC (by design) can only shootdown STLB entries (for pmd). The stray NTLB entries cause the overlap with the subsequent STLB entry for collapsed page. So make pmdp_collapse_flush() call pte flush interface not pmd flush. Note that originally all thp flush call sites in generic code called flush_tlb_range() leaving it to architecture to implement the flush for pte and/or pmd. Commit 12ebc1581ad11454 changed this by calling a new opt-in API flush_pmd_tlb_range() which made the semantics more explicit but failed to distinguish the pte vs pmd flush in generic code, which is what this patch fixes. Note that ARC can fixed w/o touching the generic pmdp_collapse_flush() by defining a ARC version, but that defeats the purpose of generic version, plus sementically this is the right thing to do. Fixes STAR 9000961194: LMBench on AXS103 triggering duplicate TLB exceptions with super pages Fixes: 12ebc1581ad11454 ("mm,thp: introduce flush_pmd_tlb_range") Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-25memcg: only free spare array when readers are doneMartijn Coenen
commit 6611d8d76132f86faa501de9451a89bf23fb2371 upstream. A spare array holding mem cgroup threshold events is kept around to make sure we can always safely deregister an event and have an array to store the new set of events in. In the scenario where we're going from 1 to 0 registered events, the pointer to the primary array containing 1 event is copied to the spare slot, and then the spare slot is freed because no events are left. However, it is freed before calling synchronize_rcu(), which means readers may still be accessing threshold->primary after it is freed. Fixed by only freeing after synchronize_rcu(). Signed-off-by: Martijn Coenen <maco@google.com> Cc: 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-25mm: fix regression in remap_file_pages() emulationKirill A. Shutemov
commit 48f7df329474b49d83d0dffec1b6186647f11976 upstream. Grazvydas Ignotas has reported a regression in remap_file_pages() emulation. Testcase: #define _GNU_SOURCE #include <assert.h> #include <stdlib.h> #include <stdio.h> #include <sys/mman.h> #define SIZE (4096 * 3) int main(int argc, char **argv) { unsigned long *p; long i; p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); if (p == MAP_FAILED) { perror("mmap"); return -1; } for (i = 0; i < SIZE / 4096; i++) p[i * 4096 / sizeof(*p)] = i; if (remap_file_pages(p, 4096, 0, 1, 0)) { perror("remap_file_pages"); return -1; } if (remap_file_pages(p, 4096 * 2, 0, 1, 0)) { perror("remap_file_pages"); return -1; } assert(p[0] == 1); munmap(p, SIZE); return 0; } The second remap_file_pages() fails with -EINVAL. The reason is that remap_file_pages() emulation assumes that the target vma covers whole area we want to over map. That assumption is broken by first remap_file_pages() call: it split the area into two vma. The solution is to check next adjacent vmas, if they map the same file with the same flags. Fixes: c8d78c1823f4 ("mm: replace remap_file_pages() syscall with emulation") Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Grazvydas Ignotas <notasas@gmail.com> Tested-by: Grazvydas Ignotas <notasas@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-25mm: replace vma_lock_anon_vma with anon_vma_lock_read/writeKonstantin Khlebnikov
commit 12352d3cae2cebe18805a91fab34b534d7444231 upstream. Sequence vma_lock_anon_vma() - vma_unlock_anon_vma() isn't safe if anon_vma appeared between lock and unlock. We have to check anon_vma first or call anon_vma_prepare() to be sure that it's here. There are only few users of these legacy helpers. Let's get rid of them. This patch fixes anon_vma lock imbalance in validate_mm(). Write lock isn't required here, read lock is enough. And reorders expand_downwards/expand_upwards: security_mmap_addr() and wrapping-around check don't have to be under anon vma lock. Link: https://lkml.kernel.org/r/CACT4Y+Y908EjM2z=706dv4rV6dWtxTLK9nFg9_7DhRMLppBo2g@mail.gmail.com Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-25mm: fix mlock accoutingKirill A. Shutemov
commit 7162a1e87b3e380133dadc7909081bb70d0a7041 upstream. Tetsuo Handa reported underflow of NR_MLOCK on munlock. Testcase: #include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #define BASE ((void *)0x400000000000) #define SIZE (1UL << 21) int main(int argc, char *argv[]) { void *addr; system("grep Mlocked /proc/meminfo"); addr = mmap(BASE, SIZE, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED | MAP_FIXED, -1, 0); if (addr == MAP_FAILED) printf("mmap() failed\n"), exit(1); munmap(addr, SIZE); system("grep Mlocked /proc/meminfo"); return 0; } It happens on munlock_vma_page() due to unfortunate choice of nr_pages data type: __mod_zone_page_state(zone, NR_MLOCK, -nr_pages); For unsigned int nr_pages, implicitly casted to long in __mod_zone_page_state(), it becomes something around UINT_MAX. munlock_vma_page() usually called for THP as small pages go though pagevec. Let's make nr_pages signed int. Similar fixes in 6cdb18ad98a4 ("mm/vmstat: fix overflow in mod_zone_page_state()") used `long' type, but `int' here is OK for a count of the number of sub-pages in a huge page. Fixes: ff6a6da60b89 ("mm: accelerate munlock() treatment of THP pages") Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Michel Lespinasse <walken@google.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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-25mm: soft-offline: check return value in second __get_any_page() callNaoya Horiguchi
commit d96b339f453997f2f08c52da3f41423be48c978f upstream. I saw the following BUG_ON triggered in a testcase where a process calls madvise(MADV_SOFT_OFFLINE) on thps, along with a background process that calls migratepages command repeatedly (doing ping-pong among different NUMA nodes) for the first process: Soft offlining page 0x60000 at 0x700000600000 __get_any_page: 0x60000 free buddy page page:ffffea0001800000 count:0 mapcount:-127 mapping: (null) index:0x1 flags: 0x1fffc0000000000() page dumped because: VM_BUG_ON_PAGE(atomic_read(&page->_count) == 0) ------------[ cut here ]------------ kernel BUG at /src/linux-dev/include/linux/mm.h:342! invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC Modules linked in: cfg80211 rfkill crc32c_intel serio_raw virtio_balloon i2c_piix4 virtio_blk virtio_net ata_generic pata_acpi CPU: 3 PID: 3035 Comm: test_alloc_gene Tainted: G O 4.4.0-rc8-v4.4-rc8-160107-1501-00000-rc8+ #74 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 task: ffff88007c63d5c0 ti: ffff88007c210000 task.ti: ffff88007c210000 RIP: 0010:[<ffffffff8118998c>] [<ffffffff8118998c>] put_page+0x5c/0x60 RSP: 0018:ffff88007c213e00 EFLAGS: 00010246 Call Trace: put_hwpoison_page+0x4e/0x80 soft_offline_page+0x501/0x520 SyS_madvise+0x6bc/0x6f0 entry_SYSCALL_64_fastpath+0x12/0x6a Code: 8b fc ff ff 5b 5d c3 48 89 df e8 b0 fa ff ff 48 89 df 31 f6 e8 c6 7d ff ff 5b 5d c3 48 c7 c6 08 54 a2 81 48 89 df e8 a4 c5 01 00 <0f> 0b 66 90 66 66 66 66 90 55 48 89 e5 41 55 41 54 53 48 8b 47 RIP [<ffffffff8118998c>] put_page+0x5c/0x60 RSP <ffff88007c213e00> The root cause resides in get_any_page() which retries to get a refcount of the page to be soft-offlined. This function calls put_hwpoison_page(), expecting that the target page is putback to LRU list. But it can be also freed to buddy. So the second check need to care about such case. Fixes: af8fae7c0886 ("mm/memory-failure.c: clean up soft_offline_page()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-25ptrace: use fsuid, fsgid, effective creds for fs access checksJann Horn
commit caaee6234d05a58c5b4d05e7bf766131b810a657 upstream. By checking the effective credentials instead of the real UID / permitted capabilities, ensure that the calling process actually intended to use its credentials. To ensure that all ptrace checks use the correct caller credentials (e.g. in case out-of-tree code or newly added code omits the PTRACE_MODE_*CREDS flag), use two new flags and require one of them to be set. The problem was that when a privileged task had temporarily dropped its privileges, e.g. by calling setreuid(0, user_uid), with the intent to perform following syscalls with the credentials of a user, it still passed ptrace access checks that the user would not be able to pass. While an attacker should not be able to convince the privileged task to perform a ptrace() syscall, this is a problem because the ptrace access check is reused for things in procfs. In particular, the following somewhat interesting procfs entries only rely on ptrace access checks: /proc/$pid/stat - uses the check for determining whether pointers should be visible, useful for bypassing ASLR /proc/$pid/maps - also useful for bypassing ASLR /proc/$pid/cwd - useful for gaining access to restricted directories that contain files with lax permissions, e.g. in this scenario: lrwxrwxrwx root root /proc/13020/cwd -> /root/foobar drwx------ root root /root drwxr-xr-x root root /root/foobar -rw-r--r-- root root /root/foobar/secret Therefore, on a system where a root-owned mode 6755 binary changes its effective credentials as described and then dumps a user-specified file, this could be used by an attacker to reveal the memory layout of root's processes or reveal the contents of files he is not allowed to access (through /proc/$pid/cwd). [akpm@linux-foundation.org: fix warning] Signed-off-by: Jann Horn <jann@thejh.net> Acked-by: Kees Cook <keescook@chromium.org> Cc: Casey Schaufler <casey@schaufler-ca.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Willy Tarreau <w@1wt.eu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-17mm, vmstat: fix wrong WQ sleep when memory reclaim doesn't make any progressTetsuo Handa
commit 564e81a57f9788b1475127012e0fd44e9049e342 upstream. Jan Stancek has reported that system occasionally hanging after "oom01" testcase from LTP triggers OOM. Guessing from a result that there is a kworker thread doing memory allocation and the values between "Node 0 Normal free:" and "Node 0 Normal:" differs when hanging, vmstat is not up-to-date for some reason. According to commit 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress"), it meant to force the kworker thread to take a short sleep, but it by error used schedule_timeout(1). We missed that schedule_timeout() in state TASK_RUNNING doesn't do anything. Fix it by using schedule_timeout_uninterruptible(1) which forces the kworker thread to take a short sleep in order to make sure that vmstat is up-to-date. Fixes: 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: Jan Stancek <jstancek@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tejun Heo <tj@kernel.org> Cc: Cristopher Lameter <clameter@sgi.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Arkadiusz Miskiewicz <arekm@maven.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-17zsmalloc: fix migrate_zspage-zs_free race conditionJunil Lee
commit c102f07ca0b04f2cb49cfc161c83f6239d17f491 upstream. record_obj() in migrate_zspage() does not preserve handle's HANDLE_PIN_BIT, set by find_aloced_obj()->trypin_tag(), and implicitly (accidentally) un-pins the handle, while migrate_zspage() still performs an explicit unpin_tag() on the that handle. This additional explicit unpin_tag() introduces a race condition with zs_free(), which can pin that handle by this time, so the handle becomes un-pinned. Schematically, it goes like this: CPU0 CPU1 migrate_zspage find_alloced_obj trypin_tag set HANDLE_PIN_BIT zs_free() pin_tag() obj_malloc() -- new object, no tag record_obj() -- remove HANDLE_PIN_BIT set HANDLE_PIN_BIT unpin_tag() -- remove zs_free's HANDLE_PIN_BIT The race condition may result in a NULL pointer dereference: Unable to handle kernel NULL pointer dereference at virtual address 00000000 CPU: 0 PID: 19001 Comm: CookieMonsterCl Tainted: PC is at get_zspage_mapping+0x0/0x24 LR is at obj_free.isra.22+0x64/0x128 Call trace: get_zspage_mapping+0x0/0x24 zs_free+0x88/0x114 zram_free_page+0x64/0xcc zram_slot_free_notify+0x90/0x108 swap_entry_free+0x278/0x294 free_swap_and_cache+0x38/0x11c unmap_single_vma+0x480/0x5c8 unmap_vmas+0x44/0x60 exit_mmap+0x50/0x110 mmput+0x58/0xe0 do_exit+0x320/0x8dc do_group_exit+0x44/0xa8 get_signal+0x538/0x580 do_signal+0x98/0x4b8 do_notify_resume+0x14/0x5c This patch keeps the lock bit in migration path and update value atomically. Signed-off-by: Junil Lee <junil0814.lee@lge.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-01-08vmstat: allocate vmstat_wq before it is usedMichal Hocko
kernel test robot has reported the following crash: BUG: unable to handle kernel NULL pointer dereference at 00000100 IP: [<c1074df6>] __queue_work+0x26/0x390 *pdpt = 0000000000000000 *pde = f000ff53f000ff53 *pde = f000ff53f000ff53 Oops: 0000 [#1] PREEMPT PREEMPT SMP SMP CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted 4.4.0-rc4-00139-g373ccbe #1 Workqueue: events vmstat_shepherd task: cb684600 ti: cb7ba000 task.ti: cb7ba000 EIP: 0060:[<c1074df6>] EFLAGS: 00010046 CPU: 0 EIP is at __queue_work+0x26/0x390 EAX: 00000046 EBX: cbb37800 ECX: cbb37800 EDX: 00000000 ESI: 00000000 EDI: 00000000 EBP: cb7bbe68 ESP: cb7bbe38 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 CR0: 8005003b CR2: 00000100 CR3: 01fd5000 CR4: 000006b0 Stack: Call Trace: __queue_delayed_work+0xa1/0x160 queue_delayed_work_on+0x36/0x60 vmstat_shepherd+0xad/0xf0 process_one_work+0x1aa/0x4c0 worker_thread+0x41/0x440 kthread+0xb0/0xd0 ret_from_kernel_thread+0x21/0x40 The reason is that start_shepherd_timer schedules the shepherd work item which uses vmstat_wq (vmstat_shepherd) before setup_vmstat allocates that workqueue so if the further initialization takes more than HZ we might end up scheduling on a NULL vmstat_wq. This is really unlikely but not impossible. Fixes: 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress") Reported-by: kernel test robot <ying.huang@linux.intel.com> Signed-off-by: Michal Hocko <mhocko@suse.com> Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: stable@vger.kernel.org Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-29mm/vmstat: fix overflow in mod_zone_page_state()Heiko Carstens
mod_zone_page_state() takes a "delta" integer argument. delta contains the number of pages that should be added or subtracted from a struct zone's vm_stat field. If a zone is larger than 8TB this will cause overflows. E.g. for a zone with a size slightly larger than 8TB the line mod_zone_page_state(zone, NR_ALLOC_BATCH, zone->managed_pages); in mm/page_alloc.c:free_area_init_core() will result in a negative result for the NR_ALLOC_BATCH entry within the zone's vm_stat, since 8TB contain 0x8xxxxxxx pages which will be sign extended to a negative value. Fix this by changing the delta argument to long type. This could fix an early boot problem seen on s390, where we have a 9TB system with only one node. ZONE_DMA contains 2GB and ZONE_NORMAL the rest. The system is trying to allocate a GFP_DMA page but ZONE_DMA is completely empty, so it tries to reclaim pages in an endless loop. This was seen on a heavily patched 3.10 kernel. One possible explaination seem to be the overflows caused by mod_zone_page_state(). Unfortunately I did not have the chance to verify that this patch actually fixes the problem, since I don't have access to the system right now. However the overflow problem does exist anyway. Given the description that a system with slightly less than 8TB does work, this seems to be a candidate for the observed problem. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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