• David Rientjes's avatar
    oom: serialize out of memory calls · ff0ceb9d
    David Rientjes authored
    A final allocation attempt with a very high watermark needs to be attempted
    before invoking out_of_memory().  OOM killer serialization needs to occur
    before this final attempt, otherwise tasks attempting to OOM-lock all zones in
    its zonelist may spin and acquire the lock unnecessarily after the OOM
    condition has already been alleviated.
    
    If the final allocation does succeed, the zonelist is simply OOM-unlocked and
    __alloc_pages() returns the page.  Otherwise, the OOM killer is invoked.
    
    If the task cannot acquire OOM-locks on all zones in its zonelist, it is put
    to sleep and the allocation is retried when it gets rescheduled.  One of its
    zones is already marked as being in the OOM killer so it'll hopefully be
    getting some free memory soon, at least enough to satisfy a high watermark
    allocation attempt.  This prevents needlessly killing a task when the OOM
    condition would have already been alleviated if it had simply been given
    enough time.
    
    Cc: Andrea Arcangeli <andrea@suse.de>
    Acked-by: default avatarChristoph Lameter <clameter@sgi.com>
    Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    ff0ceb9d
page_alloc.c 123 KB