The patch titled
memcg: fix direct softlimit reclaim to be called in limit path
has been removed from the -mm tree. Its filename was
memcg-fix-direct-softlimit-reclaim-to-be-called-in-limit-path.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: memcg: fix direct softlimit reclaim to be called in limit path
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
commit d149e3b ("memcg: add the soft_limit reclaim in global direct
reclaim") adds a softlimit hook to shrink_zones(). By this, soft limit is
called as
try_to_free_pages()
do_try_to_free_pages()
shrink_zones()
mem_cgroup_soft_limit_reclaim()
Then, direct reclaim is memcg softlimit hint aware, now.
But, the memory cgroup's "limit" path can call softlimit shrinker.
try_to_free_mem_cgroup_pages()
do_try_to_free_pages()
shrink_zones()
mem_cgroup_soft_limit_reclaim()
This will cause a global reclaim when a memcg hits limit.
This is bug. soft_limit_reclaim() should be called when
scanning_global_lru(sc) == true.
And the commit adds a variable "total_scanned" for counting softlimit
scanned pages....it's not "total". This patch removes the variable and
update sc->nr_scanned instead of it. This will affect shrink_slab()'s
scan condition but, global LRU is scanned by softlimit and I think this
change makes sense.
TODO: avoid too much scanning of a zone when softlimit did enough work.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Cc: Ying Han <yinghan@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)
diff -puN mm/vmscan.c~memcg-fix-direct-softlimit-reclaim-to-be-called-in-limit-path mm/vmscan.c
--- a/mm/vmscan.c~memcg-fix-direct-softlimit-reclaim-to-be-called-in-limit-path
+++ a/mm/vmscan.c
@@ -1995,14 +1995,13 @@ restart:
* If a zone is deemed to be full of pinned pages then just give it a light
* scan then give up on it.
*/
-static unsigned long shrink_zones(int priority, struct zonelist *zonelist,
+static void shrink_zones(int priority, struct zonelist *zonelist,
struct scan_control *sc)
{
struct zoneref *z;
struct zone *zone;
unsigned long nr_soft_reclaimed;
unsigned long nr_soft_scanned;
- unsigned long total_scanned = 0;
for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(sc->gfp_mask), sc->nodemask) {
@@ -2017,19 +2016,23 @@ static unsigned long shrink_zones(int pr
continue;
if (zone->all_unreclaimable && priority != DEF_PRIORITY)
continue; /* Let kswapd poll it */
+ /*
+ * This steals pages from memory cgroups over softlimit
+ * and returns the number of reclaimed pages and
+ * scanned pages. This works for global memory pressure
+ * and balancing, not for a memcg's limit.
+ */
+ nr_soft_scanned = 0;
+ nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
+ sc->order, sc->gfp_mask,
+ &nr_soft_scanned);
+ sc->nr_reclaimed += nr_soft_reclaimed;
+ sc->nr_scanned += nr_soft_scanned;
+ /* need some check for avoid more shrink_zone() */
}
- nr_soft_scanned = 0;
- nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
- sc->order, sc->gfp_mask,
- &nr_soft_scanned);
- sc->nr_reclaimed += nr_soft_reclaimed;
- total_scanned += nr_soft_scanned;
-
shrink_zone(priority, zone, sc);
}
-
- return total_scanned;
}
static bool zone_reclaimable(struct zone *zone)
@@ -2094,7 +2097,7 @@ static unsigned long do_try_to_free_page
sc->nr_scanned = 0;
if (!priority)
disable_swap_token(sc->mem_cgroup);
- total_scanned += shrink_zones(priority, zonelist, sc);
+ shrink_zones(priority, zonelist, sc);
/*
* Don't shrink slabs when reclaiming memory from
* over limit cgroups
_
Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are
mm-page_cgroupc-simplify-code-by-using-section_align_up-and-section_align_down-macros.patch
memcg-do-not-expose-uninitialized-mem_cgroup_per_node-to-world.patch
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