linux-kernel - Re: [PATCH] mm: memory-failure: remove unneeded page state check in shake

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Message-ID: <20230626005221.GA353339@ik1-406-35019.vs.sakura.ne.jp>
Date:   Mon, 26 Jun 2023 09:52:21 +0900
From:   Naoya Horiguchi <naoya.horiguchi@...ux.dev>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     akpm@...ux-foundation.org, naoya.horiguchi@....com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH] mm: memory-failure: remove unneeded page state check in
 shake_page()

On Sun, Jun 25, 2023 at 07:34:30PM +0800, Miaohe Lin wrote:
> Remove unneeded PageLRU(p) and is_free_buddy_page(p) check as slab caches
> are not shrunk now. This check can be added back when a lightweight range
> based shrinker is available.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>

This looks to me a good cleanup because the result of
"if (PageLRU(p) || is_free_buddy_page(p))" check is not used, so the check
itself is unneeded.

> ---
>  mm/memory-failure.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 5b663eca1f29..92f951df3e87 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -373,11 +373,10 @@ void shake_page(struct page *p)
>  	if (PageHuge(p))
>  		return;
>  
> -	if (!PageSlab(p)) {
> -		lru_add_drain_all();
> -		if (PageLRU(p) || is_free_buddy_page(p))
> -			return;
> -	}
> +	if (PageSlab(p))
> +		return;
> +
> +	lru_add_drain_all();
>  
>  	/*
>  	 * TODO: Could shrink slab caches here if a lightweight range-based

I think that this TODO comment can be put together with "if (PageSlab)" block.

Thanks,
Naoya Horiguchi