The reads of slab->slabs are racy because it may be changed by
put_cpu_partial concurrently. And in slabs_cpu_partial_show ->slabs is
only used for output. Data-racy reads from shared variables that are used
only for diagnostic purposes should typically use data_race(), since it
is normally not a problem if the values are off by a little.
This patch is aimed at reducing the number of benign races reported by
KCSAN in order to focus future debugging effort on harmful races.
Signed-off-by: linke li <lilinke99@xxxxxx>
---
mm/slub.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 2ef88bbf56a3..7b20591e7f8a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -6257,7 +6257,7 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
if (slab)
- slabs += slab->slabs;
+ slabs += data_race(slab->slabs);
}
#endif
@@ -6271,7 +6271,7 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
if (slab) {
- slabs = READ_ONCE(slab->slabs);
+ slabs = data_race(slab->slabs);
objects = (slabs * oo_objects(s->oo)) / 2;
len += sysfs_emit_at(buf, len, " C%d=%d(%d)",
cpu, objects, slabs);
--
2.39.3 (Apple Git-146)
