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

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Date:   Wed, 28 Jun 2023 09:04:51 +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 Mon, Jun 26, 2023 at 09:43:44AM +0800, Miaohe Lin wrote:
> On 2023/6/26 8:52, Naoya Horiguchi wrote:
> > 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 for your comment and advice. Do you mean something like below?

Yes, this is what I mean.  Feel free to add my ack when posting v2.

Acked-by: Naoya Horiguchi <naoya.horiguchi@....com>

Thank you.

> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 5b663eca1f29..66e7b3ceaf2d 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -372,17 +372,14 @@ 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;
> -       }
> -
>         /*
>          * TODO: Could shrink slab caches here if a lightweight range-based
>          * shrinker will be available.
>          */
> +       if (PageSlab(p))
> +               return;
> +
> +       lru_add_drain_all();
>  }
>  EXPORT_SYMBOL_GPL(shake_page);
> 
> Thanks.
> 
>