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

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Message-ID: <ZJhB45caQYmG+fwp@casper.infradead.org>
Date:   Sun, 25 Jun 2023 14:32:19 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     akpm@...ux-foundation.org, naoya.horiguchi@....com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.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.

I think your logic is faulty.  Based on the reasoning above, this patch
should be:

> -	if (!PageSlab(p)) {
> -		lru_add_drain_all();
> -		if (PageLRU(p) || is_free_buddy_page(p))
> -			return;
> -	}
> +	if (PageSlab(p))
> +		return;
> +
> +	lru_add_drain_all();
+	if (PageLRU(p) || is_free_buddy_page(p))
+		return;

but maybe it's the description that is wrong.