From: Kiryl Shutsemau <kas@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"David Hildenbrand (Arm)" <david@kernel.org>,
Pedro Falcato <pfalcato@suse.de>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Hugh Dickins <hughd@google.com>,
Chris Mason <mason@kernel.org>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@meta.com,
Sashiko <sashiko-bot@kernel.org>
Subject: Re: [PATCH v2 1/2] mm/memory: recheck PG_uptodate after ->page_mkwrite()
Date: Tue, 10 Nov 2026 10:38:34 +0000 [thread overview]
Message-ID: <avLzpIM1VdE31a-B@thinkstation> (raw)
In-Reply-To: <avItd6rDqP3GB6pL@casper.infradead.org>
On Mon, Nov 09, 2026 at 08:30:47PM +0000, Matthew Wilcox wrote:
> On Mon, Nov 09, 2026 at 12:04:01PM +0000, Kiryl Shutsemau (Meta) wrote:
> > do_shared_fault() unlocks the folio around ->page_mkwrite(). Writeback
> > can lock it in that window, fail, and clear PG_uptodate with the folio
> > left in the page cache. ecryptfs_writepages() does this when encryption
> > fails. filemap_page_mkwrite() relocks the folio and checks only
> > ->mapping, so the fault maps a folio that is not uptodate:
>
> Filesystems that do this are buggy. They shuld be fixed, not worked
> around like this.
Fair. What is your take on the way out?
Is there a timeline for the filesystem fixes?
Until they land, mm should still not map a folio that is not uptodate.
Would WARN_ON_ONCE() and SIGBUS, like the other checks in 2/2, work for
you? It flags the buggy filesystem instead of hiding it.
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2026-11-10 10:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-09 12:04 [PATCH v2 0/2] mm/memory: refuse to map page cache folios that are not uptodate Kiryl Shutsemau (Meta)
2026-11-09 12:04 ` [PATCH v2 1/2] mm/memory: recheck PG_uptodate after ->page_mkwrite() Kiryl Shutsemau (Meta)
2026-11-09 14:11 ` Pedro Falcato
2026-11-09 14:40 ` Kiryl Shutsemau
2026-11-09 16:11 ` Lorenzo Stoakes (ARM)
2026-11-09 17:17 ` Kiryl Shutsemau
2026-11-09 17:30 ` Lorenzo Stoakes (ARM)
2026-11-09 20:30 ` Matthew Wilcox
2026-11-10 10:38 ` Kiryl Shutsemau [this message]
2026-11-09 12:04 ` [PATCH v2 2/2] mm/memory: refuse to map page cache folios that are not uptodate Kiryl Shutsemau (Meta)
2026-11-09 14:13 ` Pedro Falcato
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