linux-kernel - Re: [PATCHv2 2/5] mm/rmap: Fix a mlock race condition in folio_referenced

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: <vc7lycvsvehisjr5drbng2lupytme3grubxbtgavvvjknkgzd6@axgctxng4424>
Date: Fri, 19 Sep 2025 14:18:56 -0700
From: Shakeel Butt <shakeel.butt@...ux.dev>
To: Kiryl Shutsemau <kirill@...temov.name>
Cc: Andrew Morton <akpm@...ux-foundation.org>, 
	David Hildenbrand <david@...hat.com>, Hugh Dickins <hughd@...gle.com>, 
	Matthew Wilcox <willy@...radead.org>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
	"Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka <vbabka@...e.cz>, 
	Mike Rapoport <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>, 
	Michal Hocko <mhocko@...e.com>, Rik van Riel <riel@...riel.com>, 
	Harry Yoo <harry.yoo@...cle.com>, Johannes Weiner <hannes@...xchg.org>, 
	Baolin Wang <baolin.wang@...ux.alibaba.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	Kiryl Shutsemau <kas@...nel.org>
Subject: Re: [PATCHv2 2/5] mm/rmap: Fix a mlock race condition in
 folio_referenced_one()

On Fri, Sep 19, 2025 at 01:40:33PM +0100, Kiryl Shutsemau wrote:
> From: Kiryl Shutsemau <kas@...nel.org>
> 
> The mlock_vma_folio() function requires the page table lock to be held
> in order to safely mlock the folio. However, folio_referenced_one()
> mlocks a large folios outside of the page_vma_mapped_walk() loop where
> the page table lock has already been dropped.
> 
> Rework the mlock logic to use the same code path inside the loop for
> both large and small folios.
> 
> Use PVMW_PGTABLE_CROSSED to detect when the folio is mapped across a
> page table boundary.
> 
> Signed-off-by: Kiryl Shutsemau <kas@...nel.org>

Nice, this simplifies the code.

Reviewed-by: Shakeel Butt <shakeel.butt@...ux.dev>