This is a note to let you know that I've just added the patch titled

mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: mm-fix-check-for-reclaimable-pages-in-pf_memalloc-reclaim-throttling.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Thu Mar 22 14:40:24 CET 2018

From: Johannes Weiner hannes@cmpxchg.org Date: Wed, 3 May 2017 14:51:54 -0700 Subject: mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling

From: Johannes Weiner hannes@cmpxchg.org

[ Upstream commit d450abd81b081d45adb12f303a07dd44b15eb1bc ]

PF_MEMALLOC direct reclaimers get throttled on a node when the sum of all free pages in each zone fall below half the min watermark. During the summation, we want to exclude zones that don't have reclaimables. Checking the same pgdat over and over again doesn't make sense.

Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node") Link: http://lkml.kernel.org/r/20170228214007.5621-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner hannes@cmpxchg.org Acked-by: Hillf Danton hillf.zj@alibaba-inc.com Acked-by: Michal Hocko mhocko@suse.com Cc: Jia He hejianet@gmail.com Cc: Mel Gorman mgorman@suse.de Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/vmscan.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2841,8 +2841,10 @@ static bool allow_direct_reclaim(pg_data

for (i = 0; i <= ZONE_NORMAL; i++) { zone = &pgdat->node_zones[i]; - if (!managed_zone(zone) || - pgdat_reclaimable_pages(pgdat) == 0) + if (!managed_zone(zone)) + continue; + + if (!zone_reclaimable_pages(zone)) continue;

pfmemalloc_reserve += min_wmark_pages(zone);

Patches currently in stable-queue which might be from hannes@cmpxchg.org are

queue-4.9/mm-fix-check-for-reclaimable-pages-in-pf_memalloc-reclaim-throttling.patch queue-4.9/mm-vmstat-suppress-pcp-stats-for-unpopulated-zones-in-zoneinfo.patch