linux/mm
Johannes Weiner cd324edce5 mm: memcontrol: handle div0 crash race condition in memory.low
Tejun reports seeing rare div0 crashes in memory.low stress testing:

  RIP: 0010:mem_cgroup_calculate_protection+0xed/0x150
  Code: 0f 46 d1 4c 39 d8 72 57 f6 05 16 d6 42 01 40 74 1f 4c 39 d8 76 1a 4c 39 d1 76 15 4c 29 d1 4c 29 d8 4d 29 d9 31 d2 48 0f af c1 <49> f7 f1 49 01 c2 4c 89 96 38 01 00 00 5d c3 48 0f af c7 31 d2 49
  RSP: 0018:ffffa14e01d6fcd0 EFLAGS: 00010246
  RAX: 000000000243e384 RBX: 0000000000000000 RCX: 0000000000008f4b
  RDX: 0000000000000000 RSI: ffff8b89bee84000 RDI: 0000000000000000
  RBP: ffffa14e01d6fcd0 R08: ffff8b89ca7d40f8 R09: 0000000000000000
  R10: 0000000000000000 R11: 00000000006422f7 R12: 0000000000000000
  R13: ffff8b89d9617000 R14: ffff8b89bee84000 R15: ffffa14e01d6fdb8
  FS:  0000000000000000(0000) GS:ffff8b8a1f1c0000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f93b1fc175b CR3: 000000016100a000 CR4: 0000000000340ea0
  Call Trace:
    shrink_node+0x1e5/0x6c0
    balance_pgdat+0x32d/0x5f0
    kswapd+0x1d7/0x3d0
    kthread+0x11c/0x160
    ret_from_fork+0x1f/0x30

This happens when parent_usage == siblings_protected.

We check that usage is bigger than protected, which should imply
parent_usage being bigger than siblings_protected.  However, we don't
read (or even update) these values atomically, and they can be out of
sync as the memory state changes under us.  A bit of fluctuation around
the target protection isn't a big deal, but we need to handle the div0
case.

Check the parent state explicitly to make sure we have a reasonable
positive value for the divisor.

Link: http://lkml.kernel.org/r/20200615140658.601684-1-hannes@cmpxchg.org
Fixes: 8a931f8013 ("mm: memcontrol: recursive memory.low protection")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Chris Down <chris@chrisdown.name>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-26 00:27:37 -07:00
..
kasan mm: remove __ARCH_HAS_5LEVEL_HACK and include/asm-generic/5level-fixup.h 2020-06-04 19:06:21 -07:00
backing-dev.c bdi: remove the name field in struct backing_dev_info 2020-05-09 16:15:13 -06:00
balloon_compaction.c
cleancache.c
cma_debug.c mm/cma_debug.c: use DEFINE_DEBUGFS_ATTRIBUTE to define debugfs fops 2019-12-01 12:59:09 -08:00
cma.c mm: cma: NUMA node interface 2020-04-10 15:36:21 -07:00
cma.h
compaction.c mm, compaction: make capture control handling safe wrt interrupts 2020-06-26 00:27:36 -07:00
debug_page_ref.c
debug_vm_pgtable.c mm/debug_vm_pgtable: fix build failure with powerpc 8xx 2020-06-26 00:27:37 -07:00
debug.c maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault 2020-06-17 10:57:41 -07:00
dmapool.c mm/dmapool.c: micro-optimisation remove unnecessary branch 2020-04-07 10:43:42 -07:00
early_ioremap.c mm/early_ioremap.c: use %pa to print resource_size_t variables 2020-01-31 10:30:38 -08:00
fadvise.c mm: return void from various readahead functions 2020-06-02 10:59:06 -07:00
failslab.c
filemap.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
frame_vector.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
frontswap.c mm/frontswap: fix some typos in frontswap.c 2020-06-04 19:06:24 -07:00
gup_benchmark.c mm/gup_benchmark: support pin_user_pages() and related calls 2020-04-02 09:35:27 -07:00
gup.c mm: Allow arches to provide ptep_get() 2020-06-20 22:14:53 +10:00
highmem.c mm, x86/mm: Untangle address space layout definitions from basic pgtable type definitions 2019-12-10 10:12:55 +01:00
hmm.c mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked() 2020-06-09 09:39:14 -07:00
huge_memory.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
hugetlb_cgroup.c mm: use fallthrough; 2020-04-07 10:43:41 -07:00
hugetlb.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
hwpoison-inject.c mm/hwpoison-inject: use DEFINE_DEBUGFS_ATTRIBUTE to define debugfs fops 2019-12-01 12:59:09 -08:00
init-mm.c mmap locking API: add MMAP_LOCK_INITIALIZER 2020-06-09 09:39:14 -07:00
internal.h mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
interval_tree.c
Kconfig Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next 2020-06-07 17:25:29 -07:00
Kconfig.debug treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
khugepaged.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
kmemleak-test.c
kmemleak.c mm/kmemleak.c: use address-of operator on section symbols 2020-04-02 09:35:26 -07:00
ksm.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
list_lru.c mm/list_lru: fix a typo in comment "numbesr"->"numbers" 2020-06-04 19:06:24 -07:00
maccess.c maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault 2020-06-17 10:57:41 -07:00
madvise.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
Makefile The Kernel Concurrency Sanitizer (KCSAN) 2020-06-11 18:55:43 -07:00
mapping_dirty_helpers.c mm/mapping_dirty_helpers: update huge page-table entry callbacks 2020-04-02 09:35:29 -07:00
memblock.c mm/memblock: fix a typo in comment "implict"->"implicit" 2020-06-04 19:06:23 -07:00
memcontrol.c mm: memcontrol: handle div0 crash race condition in memory.low 2020-06-26 00:27:37 -07:00
memfd.c mm: page cache: store only head pages in i_pages 2019-09-24 15:54:08 -07:00
memory_hotplug.c virtio: features, fixes 2020-06-10 13:42:09 -07:00
memory-failure.c mm/memory-failure: send SIGBUS(BUS_MCEERR_AR) only to current thread 2020-06-11 18:17:47 -07:00
memory.c mm/memory.c: properly pte_offset_map_lock/unlock in vm_insert_pages() 2020-06-26 00:27:37 -07:00
mempolicy.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mempool.c
memremap.c mm/memremap: set caching mode for PCI P2PDMA memory to WC 2020-04-10 15:36:21 -07:00
memtest.c
migrate.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mincore.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
mlock.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mm_init.c mm/mm_init.c: report kasan-tag information stored in page->flags 2020-06-02 10:59:12 -07:00
mmap.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mmu_gather.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mmu_notifier.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mmzone.c
mprotect.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
mremap.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
msync.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
nommu.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
oom_kill.c kernel: better document the use_mm/unuse_mm API contract 2020-06-10 19:14:18 -07:00
page_alloc.c virtio: features, fixes 2020-06-10 13:42:09 -07:00
page_counter.c mm, memcg: prevent memory.min load/store tearing 2020-04-02 09:35:29 -07:00
page_ext.c mm/page_ext.c: drop pfn_present() check when onlining 2020-04-07 10:43:40 -07:00
page_idle.c mm/page_idle.c: skip offline pages 2020-06-08 11:05:55 -07:00
page_io.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
page_isolation.c mm: Allow to offline unmovable PageOffline() pages via MEM_GOING_OFFLINE 2020-06-04 15:36:52 -04:00
page_owner.c mm: rename gfpflags_to_migratetype to gfp_migratetype for same convention 2020-06-03 20:09:45 -07:00
page_poison.c
page_reporting.c mm/page_reporting: add budget limit on how many pages can be reported per pass 2020-04-07 10:43:39 -07:00
page_reporting.h mm: introduce include/linux/pgtable.h 2020-06-09 09:39:13 -07:00
page_vma_mapped.c mm/page_vma_mapped.c: explicitly compare pfn for normal, hugetlbfs and THP page 2020-01-31 10:30:38 -08:00
page-writeback.c mm/page-writeback: fix a typo in comment "effictive"->"effective" 2020-06-04 19:06:24 -07:00
pagewalk.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
percpu-internal.h
percpu-km.c
percpu-stats.c percpu: update copyright emails to dennis@kernel.org 2020-04-01 10:09:12 -07:00
percpu-vm.c
percpu.c mm: remove the pgprot argument to __vmalloc 2020-06-02 10:59:11 -07:00
pgtable-generic.c mm: introduce include/linux/pgtable.h 2020-06-09 09:39:13 -07:00
process_vm_access.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
ptdump.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
readahead.c mm: use memalloc_nofs_save in readahead path 2020-06-02 10:59:07 -07:00
rmap.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
rodata_test.c maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault 2020-06-17 10:57:41 -07:00
shmem.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
shuffle.c mm: adjust shuffle code to allow for future coalescing 2020-04-07 10:43:38 -07:00
shuffle.h mm: adjust shuffle code to allow for future coalescing 2020-04-07 10:43:38 -07:00
slab_common.c mm/slab: use memzero_explicit() in kzfree() 2020-06-26 00:27:37 -07:00
slab.c mm/page_alloc: integrate classzone_idx and high_zoneidx 2020-06-03 20:09:44 -07:00
slab.h mm, slab: fix sign conversion problem in memcg_uncharge_slab() 2020-06-26 00:27:37 -07:00
slob.c mm/sl[uo]b: export __kmalloc_track(_node)_caller 2020-03-26 14:45:51 +01:00
slub.c slub: cure list_slab_objects() from double fix 2020-06-26 00:27:37 -07:00
sparse-vmemmap.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
sparse.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
swap_cgroup.c mm: memcontrol: make swap tracking an integral part of memory control 2020-06-03 20:09:48 -07:00
swap_slots.c mm/swap_slots.c: assign|reset cache slot by value directly 2020-04-02 09:35:27 -07:00
swap_state.c mm: fix swap cache node allocation mask 2020-06-26 00:27:37 -07:00
swap.c mm: swap: memcg: fix memcg stats for huge pages 2020-06-03 20:09:49 -07:00
swapfile.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
truncate.c mm/thp: allow dropping THP from page cache 2019-10-19 06:32:33 -04:00
usercopy.c
userfaultfd.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
util.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
vmacache.c kernel: better document the use_mm/unuse_mm API contract 2020-06-10 19:14:18 -07:00
vmalloc.c mm/vmalloc.c: fix a warning while make xmldocs 2020-06-26 00:27:37 -07:00
vmpressure.c mm: vmpressure: use mem_cgroup_is_root API 2020-04-02 09:35:31 -07:00
vmscan.c mm/vmsan: fix some typos in comment 2020-06-04 19:06:23 -07:00
vmstat.c mm/vmstat.c: convert to use DEFINE_SEQ_ATTRIBUTE macro 2020-06-04 19:06:26 -07:00
workingset.c mm: vmscan: reclaim writepage is IO cost 2020-06-03 20:09:49 -07:00
z3fold.c mm/z3fold: silence kmemleak false positives of slots 2020-05-28 11:35:40 -07:00
zbud.c mm: use false for bool variable 2020-06-04 19:06:24 -07:00
zpool.c zpool: add malloc_support_movable to zpool_driver 2019-09-24 15:54:12 -07:00
zsmalloc.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
zswap.c mm/zswap: allow setting default status, compressor and allocator in Kconfig 2020-04-07 10:43:41 -07:00