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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Makefile | -rw-r--r-- | 563 bytes |
README | -rw-r--r-- | 1.4 KB |
bindec.S | -rw-r--r-- | 27.5 KB |
binstr.S | -rw-r--r-- | 4.2 KB |
bugfix.S | -rw-r--r-- | 13.7 KB |
decbin.S | -rw-r--r-- | 15.4 KB |
do_func.S | -rw-r--r-- | 13.5 KB |
fpsp.h | -rw-r--r-- | 11.2 KB |
gen_except.S | -rw-r--r-- | 12.9 KB |
get_op.S | -rw-r--r-- | 19.9 KB |
kernel_ex.S | -rw-r--r-- | 13.0 KB |
res_func.S | -rw-r--r-- | 51.9 KB |
round.S | -rw-r--r-- | 16.4 KB |
sacos.S | -rw-r--r-- | 2.8 KB |
sasin.S | -rw-r--r-- | 2.3 KB |
satan.S | -rw-r--r-- | 15.6 KB |
satanh.S | -rw-r--r-- | 2.2 KB |
scale.S | -rw-r--r-- | 8.7 KB |
scosh.S | -rw-r--r-- | 2.9 KB |
setox.S | -rw-r--r-- | 27.7 KB |
sgetem.S | -rw-r--r-- | 3.6 KB |
sint.S | -rw-r--r-- | 5.6 KB |
skeleton.S | -rw-r--r-- | 11.5 KB |
slog2.S | -rw-r--r-- | 5.1 KB |
slogn.S | -rw-r--r-- | 19.0 KB |
smovecr.S | -rw-r--r-- | 4.2 KB |
srem_mod.S | -rw-r--r-- | 12.0 KB |
ssin.S | -rw-r--r-- | 18.6 KB |
ssinh.S | -rw-r--r-- | 3.3 KB |
stan.S | -rw-r--r-- | 13.0 KB |
stanh.S | -rw-r--r-- | 4.0 KB |
sto_res.S | -rw-r--r-- | 1.9 KB |
stwotox.S | -rw-r--r-- | 12.0 KB |
tbldo.S | -rw-r--r-- | 18.8 KB |
util.S | -rw-r--r-- | 16.7 KB |
x_bsun.S | -rw-r--r-- | 990 bytes |
x_fline.S | -rw-r--r-- | 2.9 KB |
x_operr.S | -rw-r--r-- | 9.6 KB |
x_ovfl.S | -rw-r--r-- | 4.6 KB |
x_snan.S | -rw-r--r-- | 6.5 KB |
x_store.S | -rw-r--r-- | 6.8 KB |
x_unfl.S | -rw-r--r-- | 6.8 KB |
x_unimp.S | -rw-r--r-- | 2.0 KB |
x_unsupp.S | -rw-r--r-- | 2.2 KB |
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