The patch titled
Subject: selftests: cgroup: fix test_kmem_basic false positives
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
selftests-cgroup-fix-test_kmem_basic-false-positives.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-cgroup-fix-test_kmem_basic-false-positives.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: selftests: cgroup: fix test_kmem_basic false positives
Date: Tue, 1 Aug 2023 09:56:32 -0400
This test fails routinely in our prod testing environment, and I can
reproduce it locally as well.
The test allocates dcache inside a cgroup, then drops the memory limit
and checks that usage drops correspondingly. The reason it fails is
because dentries are freed with an RCU delay - a debugging sleep shows
that usage drops as expected shortly after.
Insert a 1s sleep after dropping the limit. This should be good
enough, assuming that machines running those tests are otherwise not
very busy.
Link: https://lkml.kernel.org/r/20230801135632.1768830-1-hannes@xxxxxxxxxxx
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/cgroup/test_kmem.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/tools/testing/selftests/cgroup/test_kmem.c~selftests-cgroup-fix-test_kmem_basic-false-positives
+++ a/tools/testing/selftests/cgroup/test_kmem.c
@@ -70,6 +70,10 @@ static int test_kmem_basic(const char *r
goto cleanup;
cg_write(cg, "memory.high", "1M");
+
+ /* wait for RCU freeing */
+ sleep(1);
+
slab1 = cg_read_key_long(cg, "memory.stat", "slab ");
if (slab1 <= 0)
goto cleanup;
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
mm-compaction-fix-endless-looping-over-same-migrate-block.patch
selftests-cgroup-fix-test_kmem_basic-false-positives.patch
mm-kill-frontswap.patch
mm-kill-frontswap-fix.patch
mm-zswap-use-zswap_invalidate_entry-for-duplicates.patch
mm-zswap-tighten-up-entry-invalidation.patch
mm-zswap-kill-zswap_get_swap_cache_page.patch
