lkml.org 
[lkml]   [2015]   [Dec]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v2] mm, oom: Give __GFP_NOFAIL allocations access to memory reserves
    Date
    From: Michal Hocko <mhocko@suse.com>

    __GFP_NOFAIL is a big hammer used to ensure that the allocation
    request can never fail. This is a strong requirement and as such
    it also deserves a special treatment when the system is OOM. The
    primary problem here is that the allocation request might have
    come with some locks held and the oom victim might be blocked
    on the same locks. This is basically an OOM deadlock situation.

    This patch tries to reduce the risk of such a deadlocks by giving
    __GFP_NOFAIL allocations a special treatment and let them dive into
    memory reserves after oom killer invocation. This should help them
    to make a progress and release resources they are holding. The OOM
    victim should compensate for the reserves consumption.

    Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
    Signed-off-by: Michal Hocko <mhocko@suse.com>
    ---
    mm/page_alloc.c | 15 ++++++++++++++-
    1 file changed, 14 insertions(+), 1 deletion(-)

    diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    index 8034909faad2..367523b2948b 100644
    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -2766,8 +2766,21 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
    goto out;
    }
    /* Exhausted what can be done so it's blamo time */
    - if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL))
    + if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) {
    *did_some_progress = 1;
    +
    + if (gfp_mask & __GFP_NOFAIL) {
    + page = get_page_from_freelist(gfp_mask, order,
    + ALLOC_NO_WATERMARKS|ALLOC_CPUSET, ac);
    + /*
    + * fallback to ignore cpuset restriction if our nodes
    + * are depleted
    + */
    + if (!page)
    + page = get_page_from_freelist(gfp_mask, order,
    + ALLOC_NO_WATERMARKS, ac);
    + }
    + }
    out:
    mutex_unlock(&oom_lock);
    return page;
    --
    2.6.2


    \
     
     \ /
      Last update: 2015-12-02 16:41    [W:2.572 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site