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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2018-04-05 16:23:35 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-05 21:36:25 -0700
commite830c63a621e20894a663351b968706bd0efbbd0 (patch)
treedb789c35c67d00d80d91698a11fb12ed64ab26dd
parent5c9bab592f53328b3e00d7293378b714abf47a2a (diff)
downloadlinux-e830c63a621e20894a663351b968706bd0efbbd0.tar.gz
mm,vmscan: don't pretend forward progress upon shrinker_rwsem contention
Since we no longer use return value of shrink_slab() for normal reclaim, the comment is no longer true. If some do_shrink_slab() call takes unexpectedly long (root cause of stall is currently unknown) when register_shrinker()/unregister_shrinker() is pending, trying to drop caches via /proc/sys/vm/drop_caches could become infinite cond_resched() loop if many mem_cgroup are defined. For safety, let's not pretend forward progress. Link: http://lkml.kernel.org/r/201802202229.GGF26507.LVFtMSOOHFJOQF@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: Glauber Costa <glommer@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>
-rw-r--r--mm/vmscan.c10
1 files changed, 1 insertions, 9 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ca566640c448..976be140a8ce 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -442,16 +442,8 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
if (memcg && (!memcg_kmem_enabled() || !mem_cgroup_online(memcg)))
return 0;
- if (!down_read_trylock(&shrinker_rwsem)) {
- /*
- * If we would return 0, our callers would understand that we
- * have nothing else to shrink and give up trying. By returning
- * 1 we keep it going and assume we'll be able to shrink next
- * time.
- */
- freed = 1;
+ if (!down_read_trylock(&shrinker_rwsem))
goto out;
- }
list_for_each_entry(shrinker, &shrinker_list, list) {
struct shrink_control sc = {