On 10/12/2016 07:33 AM, Minchan Kim wrote:
It's weird to show that zone has enough free memory above min
watermark but OOMed with 4K GFP_KERNEL allocation due to
reserved highatomic pages. As last resort, try to unreserve
highatomic pages again and if it has moved pages to
non-highatmoc free list, retry reclaim once more.
I would move the details (OOM report etc) from the cover letter here, otherwise
they end up in Patch 1's changelog, which is less helpful.
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/page_alloc.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 18808f392718..a7472426663f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2080,7 +2080,7 @@ static void reserve_highatomic_pageblock(struct page *page, struct zone *zone,
* intense memory pressure but failed atomic allocations should be easier
* to recover from than an OOM.
*/
-static void unreserve_highatomic_pageblock(const struct alloc_context *ac)
+static bool unreserve_highatomic_pageblock(const struct alloc_context *ac)
{
struct zonelist *zonelist = ac->zonelist;
unsigned long flags;
@@ -2088,6 +2088,7 @@ static void unreserve_highatomic_pageblock(const struct alloc_context *ac)
struct zone *zone;
struct page *page;
int order;
+ bool ret = false;
for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->high_zoneidx,
ac->nodemask) {
@@ -2136,12 +2137,14 @@ static void unreserve_highatomic_pageblock(const struct alloc_context *ac)
* may increase.
*/
set_pageblock_migratetype(page, ac->migratetype);
- move_freepages_block(zone, page, ac->migratetype);
+ ret = move_freepages_block(zone, page, ac->migratetype);
spin_unlock_irqrestore(&zone->lock, flags);
- return;
+ return ret;
}
spin_unlock_irqrestore(&zone->lock, flags);
}
+
+ return ret;
}
/* Remove an element from the buddy allocator from the fallback list */
@@ -3457,8 +3460,12 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order,
* Make sure we converge to OOM if we cannot make any progress
* several times in the row.
*/
- if (*no_progress_loops > MAX_RECLAIM_RETRIES)
+ if (*no_progress_loops > MAX_RECLAIM_RETRIES) {
+ /* Before OOM, exhaust highatomic_reserve */
+ if (unreserve_highatomic_pageblock(ac))
+ return true;
return false;
+ }
/*
* Keep reclaiming pages while there is a chance this will lead
--
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