On Mon, 10 Aug 2020, wuyun.wu@xxxxxxxxxx wrote:
> From: Abel Wu <wuyun.wu@xxxxxxxxxx>
>
> The commit below is incomplete, as it didn't handle the add_full() part.
> commit a4d3f8916c65 ("slub: remove useless kmem_cache_debug() before remove_full()")
>
> Signed-off-by: Abel Wu <wuyun.wu@xxxxxxxxxx>
> ---
> mm/slub.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index fe81773..0b021b7 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2182,7 +2182,8 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page,
> }
> } else {
> m = M_FULL;
> - if (kmem_cache_debug(s) && !lock) {
> +#ifdef CONFIG_SLUB_DEBUG
> + if (!lock) {
> lock = 1;
> /*
> * This also ensures that the scanning of full
> @@ -2191,6 +2192,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page,
> */
> spin_lock(&n->list_lock);
> }
> +#endif
> }
>
> if (l != m) {
This should be functionally safe, I'm wonder if it would make sense to
only check for SLAB_STORE_USER here instead of kmem_cache_debug(),
however, since that should be the only context in which we need the
list_lock for add_full()? It seems more explicit.
