linux-kernel - Re: [PATCH 1/2] mm: vmscan: remove folio_test

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aMQ6bW-OoMWMVEFF@casper.infradead.org>
Date: Fri, 12 Sep 2025 16:21:17 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: akpm@...ux-foundation.org, hannes@...xchg.org, david@...hat.com,
	mhocko@...nel.org, zhengqi.arch@...edance.com,
	shakeel.butt@...ux.dev, lorenzo.stoakes@...cle.com,
	hughd@...gle.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mm: vmscan: remove folio_test_private() check in
 pageout()

On Fri, Sep 12, 2025 at 11:45:07AM +0800, Baolin Wang wrote:
> @@ -697,22 +697,8 @@ static pageout_t pageout(struct folio *folio, struct address_space *mapping,
>  	 * swap_backing_dev_info is bust: it doesn't reflect the
>  	 * congestion state of the swapdevs.  Easy to fix, if needed.
>  	 */
> -	if (!is_page_cache_freeable(folio))
> +	if (!is_page_cache_freeable(folio) || !mapping)
>  		return PAGE_KEEP;

I feel like we need to keep the comment (assuming it's still true ...
which it probably is, although there's nobody who would think to update
this comment if it became no longer true).  I would certainly wonder why
we can have this !mapping test.

> -		/*
> -		 * Some data journaling orphaned folios can have
> -		 * folio->mapping == NULL while being dirty with clean buffers.
> -		 */

I approve of this simplification, and I think there's more work to be
done in this area.  Thanks for doing it.