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| author | Li Wang <li.wang@linux.dev> | 2026-05-01 10:20:58 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-05-28 21:05:07 -0700 |
| commit | 5de852b6e7cddc75d7182d5503e54d3ad50d109a (patch) | |
| tree | 83539524ed45abc8f5f4bad8d96be7392d0a81fa /tools | |
| parent | ca9caa098f70e25c0edd812a640c6367e711c886 (diff) | |
| download | linux-next-history-5de852b6e7cddc75d7182d5503e54d3ad50d109a.tar.gz | |
selftests/cgroup: include slab in test_percpu_basic memory check
test_percpu_basic() currently compares memory.current against only
memory.stat:percpu after creating 1000 child cgroups.
Observed failure:
#./test_kmem
ok 1 test_kmem_basic
ok 2 test_kmem_memcg_deletion
ok 3 test_kmem_proc_kpagecgroup
ok 4 test_kmem_kernel_stacks
ok 5 test_kmem_dead_cgroups
memory.current 11530240
percpu 8440000
not ok 6 test_percpu_basic
That assumption is too strict: child cgroup creation also allocates
slab-backed metadata, so memory.current is expected to be larger than
percpu alone. One visible path is:
cgroup_mkdir()
cgroup_create()
cgroup_addrm_file()
cgroup_add_file()
__kernfs_create_file()
__kernfs_new_node()
kmem_cache_zalloc()
These kernfs allocations are charged as slab and show up in
memory.stat:slab.
Update the check to compare memory.current against (percpu + slab)
within MAX_VMSTAT_ERROR, and print slab/delta in the failure message to
improve diagnostics.
Link: https://lore.kernel.org/20260501022058.18024-3-li.wang@linux.dev
Signed-off-by: Li Wang <li.wang@linux.dev>
Reviewed-by: Waiman Long <longman@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Sayali Patil <sayalip@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/cgroup/test_kmem.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c index 69cb1b50988c4..1db0ba1226b9b 100644 --- a/tools/testing/selftests/cgroup/test_kmem.c +++ b/tools/testing/selftests/cgroup/test_kmem.c @@ -353,7 +353,7 @@ static int test_percpu_basic(const char *root) { int ret = KSFT_FAIL; char *parent, *child; - long current, percpu; + long current, percpu, slab; int i; parent = cg_name(root, "percpu_basic_test"); @@ -383,13 +383,14 @@ static int test_percpu_basic(const char *root) current = cg_read_long(parent, "memory.current"); percpu = cg_read_key_long(parent, "memory.stat", "percpu "); + slab = cg_read_key_long(parent, "memory.stat", "slab "); - if (current > 0 && percpu > 0 && labs(current - percpu) < - MAX_VMSTAT_ERROR) + if (current > 0 && percpu > 0 && slab >= 0 && + labs(current - (percpu + slab)) < MAX_VMSTAT_ERROR) ret = KSFT_PASS; else - printf("memory.current %ld\npercpu %ld\n", - current, percpu); + printf("memory.current %ld\npercpu %ld\nslab %ld\ndelta %ld\n", + current, percpu, slab, current - (percpu + slab)); cleanup_children: for (i = 0; i < 1000; i++) { |