Re: [PATCH v2 07/11] zswap: do not free the entry if its pool is NULL

[Yosry Ahmed]

On Tue, Nov 10, 2026 at 02:48:12PM +0900, Sergey Senozhatsky wrote:
> zswap_entry_free() warns if the entry has no pool (which should never
> happen), skips zs_free() and then frees the entry.  A subsequent patch
> embeds zsmalloc handle into zswap_entry, so zsmalloc object will point
> to the entry, and we cannot free the entry while the object is still
> there.
> 
> Bail out early and leak the entry, its cgroup charge and stats instead.
> 
> Suggested-by: Yosry Ahmed <yosry@xxxxxxxxxx>
> Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>

Acked-by: Yosry Ahmed <yosry@xxxxxxxxxx>

> ---
>  mm/zswap.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 1160bd34e289..dc0400d7e1a3 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -787,10 +787,11 @@ static void zswap_entry_free(struct zswap_entry *entry)
>  	struct zswap_pool *pool = zswap_entry_pool(entry);
>  
>  	zswap_lru_del(entry);
> -	if (!WARN_ON_ONCE(!pool)) {
> -		zs_free(pool->zs_pool, entry->handle);
> -		zswap_pool_put(pool);
> -	}
> +	if (WARN_ON_ONCE(!pool))
> +		return;
> +
> +	zs_free(pool->zs_pool, entry->handle);
> +	zswap_pool_put(pool);
>  	if (entry->objcg) {
>  		obj_cgroup_uncharge_zswap(entry->objcg, entry->length);
>  		obj_cgroup_put(entry->objcg);
> -- 
> 2.56.0.506.g506a7eabc5-goog
>