linux-kernel - [PATCH v3] selftests: cgroup: fix test_kmem

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Message-ID: <7d6gcuyzdjcice6qbphrmpmv5skr5jtglg375unnjxqhstvhxc@qkn6dw6bao6v>
Date:   Fri, 4 Aug 2023 15:35:29 -0400
From:   Lucas Karpinski <lkarpins@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <muchun.song@...ux.dev>, Tejun Heo <tj@...nel.org>,
        Zefan Li <lizefan.x@...edance.com>,
        Shuah Khan <shuah@...nel.org>
Cc:     Muchun Song <muchun.song@...ux.dev>, cgroups@...r.kernel.org,
        linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3] selftests: cgroup: fix test_kmem_basic less than error

test_kmem_basic creates 100,000 negative dentries, with each one mapping
to a slab object. After memory.high is set, these are reclaimed through
the shrink_slab function call which reclaims all 100,000 entries. The
test passes the majority of the time because when slab1 or current is
calculated, it is often above 0, however, 0 is also an acceptable value.

Signed-off-by: Lucas Karpinski <lkarpins@...hat.com>
---
In the previous patch, I missed a change to the variable 'current' even
after some testing as the issue was so sporadic. Current takes the slab
size into account and can also face the same issue where it fails since
the reported value is 0, which is an acceptable value.

Drop: b4abfc19 in mm-unstable
V2: https://lore.kernel.org/all/ix6vzgjqay2x7bskle7pypoint4nj66fwq7odvd5hektatvp2l@kukoifnfj3dr/

 tools/testing/selftests/cgroup/test_kmem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c
index 1b2cec9d18a4..ed2e50bb1e76 100644
--- a/tools/testing/selftests/cgroup/test_kmem.c
+++ b/tools/testing/selftests/cgroup/test_kmem.c
@@ -75,11 +75,11 @@ static int test_kmem_basic(const char *root)
 	sleep(1);
 
 	slab1 = cg_read_key_long(cg, "memory.stat", "slab ");
-	if (slab1 <= 0)
+	if (slab1 < 0)
 		goto cleanup;
 
 	current = cg_read_long(cg, "memory.current");
-	if (current <= 0)
+	if (current < 0)
 		goto cleanup;
 
 	if (slab1 < slab0 / 2 && current < slab0 / 2)
-- 
2.41.0