The patch titled
Subject: mm, oom: give __GFP_NOFAIL allocations access to memory reserves
has been added to the -mm tree. Its filename is
mm-oom-give-__gfp_nofail-allocations-access-to-memory-reserves.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-oom-give-__gfp_nofail-allocations-access-to-memory-reserves.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-oom-give-__gfp_nofail-allocations-access-to-memory-reserves.patch
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From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm, oom: give __GFP_NOFAIL allocations access to memory reserves
__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.
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Suggested-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-oom-give-__gfp_nofail-allocations-access-to-memory-reserves mm/page_alloc.c
--- a/mm/page_alloc.c~mm-oom-give-__gfp_nofail-allocations-access-to-memory-reserves
+++ a/mm/page_alloc.c
@@ -2732,8 +2732,21 @@ __alloc_pages_may_oom(gfp_t gfp_mask, un
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;
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-vmstat-allow-wq-concurrency-to-discover-memory-reclaim-doesnt-make-any-progress.patch
virtio-do-not-drop-__gfp_high-in-alloc_indirect.patch
mm-get-rid-of-__alloc_pages_high_priority.patch
mm-do-not-loop-over-alloc_no_watermarks-without-triggering-reclaim.patch
mm-vmscan-consider-isolated-pages-in-zone_reclaimable_pages.patch
mm-allow-gfp_iofs-for-page_cache_read-page-cache-allocation.patch
mm-oom-give-__gfp_nofail-allocations-access-to-memory-reserves.patch
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