linux-kernel - Re: [PATCH] mm: Do not start/end writeback for pages stored in zswap

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Message-ID: <5d051998-015c-4da4-83f0-1b4fb9009c68@linux.dev>
Date: Tue, 11 Jun 2024 17:53:06 +0800
From: Chengming Zhou <chengming.zhou@...ux.dev>
To: Usama Arif <usamaarif642@...il.com>, akpm@...ux-foundation.org
Cc: willy@...radead.org, hannes@...xchg.org, yosryahmed@...gle.com,
 nphamcs@...il.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 kernel-team@...a.com
Subject: Re: [PATCH] mm: Do not start/end writeback for pages stored in zswap

On 2024/6/10 22:30, Usama Arif wrote:
> start/end writeback combination incorrectly increments NR_WRITTEN
> counter, eventhough the pages aren't written to disk. Pages successfully
> stored in zswap should just unlock folio and return from writepage.
> 
> Signed-off-by: Usama Arif <usamaarif642@...il.com>

Looks good to me, thanks.

Reviewed-by: Chengming Zhou <chengming.zhou@...ux.dev>

> ---
>  mm/page_io.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/mm/page_io.c b/mm/page_io.c
> index a360857cf75d..501784d79977 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -196,9 +196,7 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
>  		return ret;
>  	}
>  	if (zswap_store(folio)) {
> -		folio_start_writeback(folio);
>  		folio_unlock(folio);
> -		folio_end_writeback(folio);
>  		return 0;
>  	}
>  	if (!mem_cgroup_zswap_writeback_enabled(folio_memcg(folio))) {