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 |
---|---|---|
Kconfig | -rw-r--r-- | 2.3 KB |
Makefile | -rw-r--r-- | 492 bytes |
actions.c | -rw-r--r-- | 36.8 KB |
conntrack.c | -rw-r--r-- | 43.7 KB |
conntrack.h | -rw-r--r-- | 3.0 KB |
datapath.c | -rw-r--r-- | 59.9 KB |
datapath.h | -rw-r--r-- | 7.3 KB |
dp_notify.c | -rw-r--r-- | 2.6 KB |
flow.c | -rw-r--r-- | 23.0 KB |
flow.h | -rw-r--r-- | 8.4 KB |
flow_netlink.c | -rw-r--r-- | 85.5 KB |
flow_netlink.h | -rw-r--r-- | 3.1 KB |
flow_table.c | -rw-r--r-- | 18.9 KB |
flow_table.h | -rw-r--r-- | 2.8 KB |
meter.c | -rw-r--r-- | 14.3 KB |
meter.h | -rw-r--r-- | 1.2 KB |
vport-geneve.c | -rw-r--r-- | 3.1 KB |
vport-gre.c | -rw-r--r-- | 2.7 KB |
vport-internal_dev.c | -rw-r--r-- | 7.7 KB |
vport-internal_dev.h | -rw-r--r-- | 1.0 KB |
vport-netdev.c | -rw-r--r-- | 5.4 KB |
vport-netdev.h | -rw-r--r-- | 1.1 KB |
vport-vxlan.c | -rw-r--r-- | 4.3 KB |
vport.c | -rw-r--r-- | 12.9 KB |
vport.h | -rw-r--r-- | 6.2 KB |
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...