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Date:   Tue, 7 Sep 2021 14:02:59 +0200
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Subject: Re: [PATCH] mm : bail out from psi memstall after submit_bio in
 swap_readpage
Content-Language: en-US
To:     Huangzhaoyang <huangzhaoyang@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Minchan Kim <minchan@kernel.org>,
        Zhaoyang Huang <zhaoyang.huang@unisoc.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Johannes Weiner <hannes@cmpxchg.org>
References: <1631015968-9779-1-git-send-email-huangzhaoyang@gmail.com>
From:   Vlastimil Babka <vbabka@suse.cz>
In-Reply-To: <1631015968-9779-1-git-send-email-huangzhaoyang@gmail.com>
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On 9/7/21 13:59, Huangzhaoyang wrote:
> From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> 
> It doesn't make sense to count IO time into psi memstall. Bail out after
> bio submitted.

Isn't that the point if psi, to observe real stalls, which include IO?
Anyway, CCing Johannes.

> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> ---
>  mm/page_io.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/page_io.c b/mm/page_io.c
> index c493ce9..1d131fc 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -423,6 +423,7 @@ int swap_readpage(struct page *page, bool synchronous)
>  	count_vm_event(PSWPIN);
>  	bio_get(bio);
>  	qc = submit_bio(bio);
> +	psi_memstall_leave(&pflags);
>  	while (synchronous) {
>  		set_current_state(TASK_UNINTERRUPTIBLE);
>  		if (!READ_ONCE(bio->bi_private))
> @@ -433,7 +434,7 @@ int swap_readpage(struct page *page, bool synchronous)
>  	}
>  	__set_current_state(TASK_RUNNING);
>  	bio_put(bio);
> -
> +	return ret;
>  out:
>  	psi_memstall_leave(&pflags);
>  	return ret;
>