The attribute reflects the SLAB_RECLAIM_ACCOUNT cache flag. It's not clear why
this attribute was writable in the first place, as it's tied to how the cache
is used by its creator, it's not a user tunable. Furthermore:
- it affects slab merging, but that's not being checked while toggled
- if affects whether __GFP_RECLAIMABLE flag is used to allocate page, but
the runtime toggle doesn't update allocflags
- it affects cache_vmstat_idx() so runtime toggling might lead to incosistency
of NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE
Thus make it read-only.
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Roman Gushchin <guro@xxxxxx>
---
mm/slub.c | 11 +----------
1 file changed, 1 insertion(+), 10 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 0108829838e7..8dd2925448ae 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5223,16 +5223,7 @@ static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
}
-
-static ssize_t reclaim_account_store(struct kmem_cache *s,
- const char *buf, size_t length)
-{
- s->flags &= ~SLAB_RECLAIM_ACCOUNT;
- if (buf[0] == '1')
- s->flags |= SLAB_RECLAIM_ACCOUNT;
- return length;
-}
-SLAB_ATTR(reclaim_account);
+SLAB_ATTR_RO(reclaim_account);
static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf)
{
--
2.26.2
