linux-kernel - Re: [PATCH 1/5] mm: shmem: avoid unpaired folio_unlock() in shmem_swapin

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Message-ID: <aede5e8a-4e8b-4a06-bdc4-aefc82e4e282@linux.alibaba.com>
Date: Wed, 14 May 2025 16:51:33 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: Kemeng Shi <shikemeng@...weicloud.com>, hughd@...gle.com,
 akpm@...ux-foundation.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] mm: shmem: avoid unpaired folio_unlock() in
 shmem_swapin_folio()



On 2025/5/15 00:50, Kemeng Shi wrote:
> If we get a folio from swap_cache_get_folio() successfully but encounter
> a failure before the folio is locked, we will unlock the folio which was
> not previously locked.
> Put the folio and set it to NULL when a failure occurs before the folio
> is locked to fix the issue.
> 
> Fixes: 058313515d5aa ("mm: shmem: fix potential data corruption during shmem swapin")
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>

Good catch. LGTM.
Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>

> ---
>   mm/shmem.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 99327c30507c..980fa15f393e 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2335,6 +2335,8 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
>   		 */
>   		split_order = shmem_split_large_entry(inode, index, swap, gfp);
>   		if (split_order < 0) {
> +			folio_put(folio);
> +			folio = NULL;
>   			error = split_order;
>   			goto failed;
>   		}