linux-kernel - Re: [PATCHv3 1/2] mm/memory: Do not populate page table entries beyond i

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 for Android: free password hash cracker in your pocket

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

Message-ID: <aQi9zaPxwLBTneF4@casper.infradead.org>
Date: Mon, 3 Nov 2025 14:35:57 +0000
From: Matthew Wilcox <willy@...radead.org>
To: Kiryl Shutsemau <kirill@...temov.name>
Cc: Hugh Dickins <hughd@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.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>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>,
	"Darrick J. Wong" <djwong@...nel.org>,
	Dave Chinner <david@...morbit.com>, linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv3 1/2] mm/memory: Do not populate page table entries
 beyond i_size

On Mon, Nov 03, 2025 at 10:59:00AM +0000, Kiryl Shutsemau wrote:
> On Sat, Nov 01, 2025 at 05:00:47AM +0000, Matthew Wilcox wrote:
> > On Wed, Oct 29, 2025 at 02:45:52AM -0700, Hugh Dickins wrote:
> > > But you're giving yourself too hard a time of backporting with your
> > > 5.10 Fixee 01c70267053d for 1/2: the only filesystem which set the
> > > flag then was tmpfs, which you're now excepting.  The flag got
> > > renamed later (in 5.16) and then in 5.17 at last there was another
> > > filesystem to set it.  So, this 1/2 would be
> > > 
> > > Fixes: 6795801366da ("xfs: Support large folios")
> > 
> > I haven't been able to keep up with this patchset -- sorry.
> > 
> > But this problem didn't exist until bs>PS support was added because we
> > would never add a folio to the page cache which extended beyond i_size
> > before.  We'd shrink the folio order allocated in do_page_cache_ra()
> > (actually, we still do, but page_cache_ra_unbounded() rounds it up
> > again).  So it doesn't fix that commit at all, but something far more
> > recent.
> 
> What about truncate path? We could allocate within i_size at first, then
> truncate, if truncation failed to split the folio the mapping stays
> beyond i_size.

Is it worth backporting all this way to solve this niche case?