• Michal Hocko's avatar
    mm, oom_reaper: do not attempt to reap a task more than twice · 11a410d5
    Michal Hocko authored
    oom_reaper relies on the mmap_sem for read to do its job.  Many places
    which might block readers have been converted to use down_write_killable
    and that has reduced chances of the contention a lot.  Some paths where
    the mmap_sem is held for write can take other locks and they might
    either be not prepared to fail due to fatal signal pending or too
    impractical to be changed.
    
    This patch introduces MMF_OOM_NOT_REAPABLE flag which gets set after the
    first attempt to reap a task's mm fails.  If the flag is present after
    the failure then we set MMF_OOM_REAPED to hide this mm from the oom
    killer completely so it can go and chose another victim.
    
    As a result a risk of OOM deadlock when the oom victim would be blocked
    indefinetly and so the oom killer cannot make any progress should be
    mitigated considerably while we still try really hard to perform all
    reclaim attempts and stay predictable in the behavior.
    
    Link: http://lkml.kernel.org/r/1466426628-15074-10-git-send-email-mhocko@kernel.orgSigned-off-by: default avatarMichal Hocko <mhocko@suse.com>
    Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
    Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    11a410d5
oom_kill.c 28.7 KB