Revision 4837fe37adff1d159904f0c013471b1ecbcb455e authored by Michal Hocko on 14 December 2017, 23:33:15 UTC, committed by Linus Torvalds on 15 December 2017, 00:00:49 UTC
David Rientjes has reported the following memory corruption while the oom reaper tries to unmap the victims address space BUG: Bad page map in process oom_reaper pte:6353826300000000 pmd:00000000 addr:00007f50cab1d000 vm_flags:08100073 anon_vma:ffff9eea335603f0 mapping: (null) index:7f50cab1d file: (null) fault: (null) mmap: (null) readpage: (null) CPU: 2 PID: 1001 Comm: oom_reaper Call Trace: unmap_page_range+0x1068/0x1130 __oom_reap_task_mm+0xd5/0x16b oom_reaper+0xff/0x14c kthread+0xc1/0xe0 Tetsuo Handa has noticed that the synchronization inside exit_mmap is insufficient. We only synchronize with the oom reaper if tsk_is_oom_victim which is not true if the final __mmput is called from a different context than the oom victim exit path. This can trivially happen from context of any task which has grabbed mm reference (e.g. to read /proc/<pid>/ file which requires mm etc.). The race would look like this oom_reaper oom_victim task mmget_not_zero do_exit mmput __oom_reap_task_mm mmput __mmput exit_mmap remove_vma unmap_page_range Fix this issue by providing a new mm_is_oom_victim() helper which operates on the mm struct rather than a task. Any context which operates on a remote mm struct should use this helper in place of tsk_is_oom_victim. The flag is set in mark_oom_victim and never cleared so it is stable in the exit_mmap path. Debugged by Tetsuo Handa. Link: http://lkml.kernel.org/r/20171210095130.17110-1-mhocko@kernel.org Fixes: 212925802454 ("mm: oom: let oom_reap_task and exit_mmap run concurrently") Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: David Rientjes <rientjes@google.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Andrea Argangeli <andrea@kernel.org> Cc: <stable@vger.kernel.org> [4.14] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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File | Mode | Size |
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Kconfig | -rw-r--r-- | 3.2 KB |
Makefile | -rw-r--r-- | 729 bytes |
associola.c | -rw-r--r-- | 48.7 KB |
auth.c | -rw-r--r-- | 23.9 KB |
bind_addr.c | -rw-r--r-- | 13.9 KB |
chunk.c | -rw-r--r-- | 9.8 KB |
debug.c | -rw-r--r-- | 4.3 KB |
endpointola.c | -rw-r--r-- | 12.3 KB |
input.c | -rw-r--r-- | 34.3 KB |
inqueue.c | -rw-r--r-- | 7.0 KB |
ipv6.c | -rw-r--r-- | 29.4 KB |
objcnt.c | -rw-r--r-- | 3.9 KB |
offload.c | -rw-r--r-- | 2.9 KB |
output.c | -rw-r--r-- | 23.0 KB |
outqueue.c | -rw-r--r-- | 55.5 KB |
primitive.c | -rw-r--r-- | 7.4 KB |
probe.c | -rw-r--r-- | 5.9 KB |
proc.c | -rw-r--r-- | 13.9 KB |
protocol.c | -rw-r--r-- | 42.9 KB |
sctp_diag.c | -rw-r--r-- | 13.5 KB |
sm_make_chunk.c | -rw-r--r-- | 114.4 KB |
sm_sideeffect.c | -rw-r--r-- | 51.3 KB |
sm_statefuns.c | -rw-r--r-- | 202.3 KB |
sm_statetable.c | -rw-r--r-- | 33.7 KB |
socket.c | -rw-r--r-- | 232.0 KB |
stream.c | -rw-r--r-- | 27.1 KB |
stream_sched.c | -rw-r--r-- | 6.6 KB |
stream_sched_prio.c | -rw-r--r-- | 9.0 KB |
stream_sched_rr.c | -rw-r--r-- | 5.2 KB |
sysctl.c | -rw-r--r-- | 12.5 KB |
transport.c | -rw-r--r-- | 20.9 KB |
tsnmap.c | -rw-r--r-- | 9.5 KB |
ulpevent.c | -rw-r--r-- | 31.6 KB |
ulpqueue.c | -rw-r--r-- | 29.3 KB |
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