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authorDave Chinner <dchinner@redhat.com>2019-02-12 15:35:55 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-02-20 10:29:12 +0100
commit3aea1d1b31f14f5c49e8e7df6cbfe4b0055e6bde (patch)
parent01b7eccaee41704ffe3cfbd441a1fed6367dc602 (diff)
Revert "mm: slowly shrink slabs with a relatively small number of objects"
commit a9a238e83fbb0df31c3b9b67003f8f9d1d1b6c96 upstream. This reverts commit 172b06c32b9497 ("mm: slowly shrink slabs with a relatively small number of objects"). This change changes the agressiveness of shrinker reclaim, causing small cache and low priority reclaim to greatly increase scanning pressure on small caches. As a result, light memory pressure has a disproportionate affect on small caches, and causes large caches to be reclaimed much faster than previously. As a result, it greatly perturbs the delicate balance of the VFS caches (dentry/inode vs file page cache) such that the inode/dentry caches are reclaimed much, much faster than the page cache and this drives us into several other caching imbalance related problems. As such, this is a bad change and needs to be reverted. [ Needs some massaging to retain the later seekless shrinker modifications.] Link: http://lkml.kernel.org/r/20190130041707.27750-3-david@fromorbit.com Fixes: 172b06c32b9497 ("mm: slowly shrink slabs with a relatively small number of objects") Signed-off-by: Dave Chinner <dchinner@redhat.com> Cc: Wolfgang Walter <linux@stwm.de> Cc: Roman Gushchin <guro@fb.com> Cc: Spock <dairinin@gmail.com> Cc: Rik van Riel <riel@surriel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 0 insertions, 10 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 62ac0c488624..8e377bbac3a6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -487,16 +487,6 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
delta = freeable / 2;
- /*
- * Make sure we apply some minimal pressure on default priority
- * even on small cgroups. Stale objects are not only consuming memory
- * by themselves, but can also hold a reference to a dying cgroup,
- * preventing it from being reclaimed. A dying cgroup with all
- * corresponding structures like per-cpu stats and kmem caches
- * can be really big, so it may lead to a significant waste of memory.
- */
- delta = max_t(unsigned long long, delta, min(freeable, batch_size));
total_scan += delta;
if (total_scan < 0) {
pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n",