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>
1 parent bdcf0a4
| File | Mode | Size |
|---|---|---|
| Makefile | -rw-r--r-- | 1.5 KB |
| amdtopology.c | -rw-r--r-- | 4.0 KB |
| debug_pagetables.c | -rw-r--r-- | 997 bytes |
| dump_pagetables.c | -rw-r--r-- | 13.7 KB |
| extable.c | -rw-r--r-- | 7.5 KB |
| fault.c | -rw-r--r-- | 37.9 KB |
| highmem_32.c | -rw-r--r-- | 3.2 KB |
| hugetlbpage.c | -rw-r--r-- | 5.2 KB |
| ident_map.c | -rw-r--r-- | 3.1 KB |
| init.c | -rw-r--r-- | 24.7 KB |
| init_32.c | -rw-r--r-- | 24.5 KB |
| init_64.c | -rw-r--r-- | 36.9 KB |
| iomap_32.c | -rw-r--r-- | 3.5 KB |
| ioremap.c | -rw-r--r-- | 21.8 KB |
| kasan_init_64.c | -rw-r--r-- | 8.8 KB |
| kaslr.c | -rw-r--r-- | 7.2 KB |
| kmmio.c | -rw-r--r-- | 16.1 KB |
| mem_encrypt.c | -rw-r--r-- | 23.8 KB |
| mem_encrypt_boot.S | -rw-r--r-- | 4.4 KB |
| mm_internal.h | -rw-r--r-- | 558 bytes |
| mmap.c | -rw-r--r-- | 6.9 KB |
| mmio-mod.c | -rw-r--r-- | 11.8 KB |
| mpx.c | -rw-r--r-- | 26.0 KB |
| numa.c | -rw-r--r-- | 22.7 KB |
| numa_32.c | -rw-r--r-- | 3.3 KB |
| numa_64.c | -rw-r--r-- | 251 bytes |
| numa_emulation.c | -rw-r--r-- | 13.1 KB |
| numa_internal.h | -rw-r--r-- | 765 bytes |
| pageattr-test.c | -rw-r--r-- | 5.3 KB |
| pageattr.c | -rw-r--r-- | 50.4 KB |
| pat.c | -rw-r--r-- | 28.2 KB |
| pat_internal.h | -rw-r--r-- | 1.5 KB |
| pat_rbtree.c | -rw-r--r-- | 6.8 KB |
| pf_in.c | -rw-r--r-- | 10.5 KB |
| pf_in.h | -rw-r--r-- | 1.4 KB |
| pgtable.c | -rw-r--r-- | 16.4 KB |
| pgtable_32.c | -rw-r--r-- | 2.2 KB |
| physaddr.c | -rw-r--r-- | 2.2 KB |
| physaddr.h | -rw-r--r-- | 231 bytes |
| pkeys.c | -rw-r--r-- | 6.4 KB |
| setup_nx.c | -rw-r--r-- | 1.4 KB |
| srat.c | -rw-r--r-- | 2.9 KB |
| testmmiotrace.c | -rw-r--r-- | 3.1 KB |
| tlb.c | -rw-r--r-- | 18.9 KB |
Computing file changes ...
