From: Matthew Wilcox <willy@infradead.org>
To: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Brian Foster <bfoster@redhat.com>, Barry Song <21cnbao@gmail.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Hugh Dickins <hughd@google.com>,
syzbot+178fff6149127421c2cc@syzkaller.appspotmail.com
Subject: Re: [PATCH] mm/shmem: fix uninitialized folio in shmem_symlink
Date: Tue, 6 Jan 2026 18:46:07 +0000 [thread overview]
Message-ID: <aV1Yb4r9_ukWoc8i@casper.infradead.org> (raw)
In-Reply-To: <2b12f63b-ceab-4d3e-a06f-f41e6b1b2d23@linux.alibaba.com>
On Tue, Jan 06, 2026 at 11:47:44AM +0800, Baolin Wang wrote:
> Why I prefer Barry's fix: First, the symlink folio is marked Uptodate after
> copying the symlink name, but the whole folio hasn’t been initialized, which
> seems unreasonable to me. Second, as I said before, using the 'PG_owner_2'
> flag to mark this uncommon case doesn’t seem worthwhile. Currently, IIUC the
> 'PG_owner_2' is only used by btrfs; if we ever want to remove the
> 'PG_owner_2', this uncommon symlink case shouldn’t block its removal.
PG_owner_2 is aliased with PG_mappedtodisk [1], so it's used by every
filesystem which uses buffer_heads (whether mentioned in that filesystem
or not). btrfs was switched from using private_2 to using owner_2
a little over a year ago. PG_owner_2 is not on the list of flags to be
removed; that's PG_private, PG_private_2 and PG_reserved.
[1] include/linux/page-flags.h: PG_mappedtodisk = PG_owner_2,
next prev parent reply other threads:[~2026-01-06 18:46 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-24 9:40 Barry Song
2025-12-24 17:01 ` Matthew Wilcox
2025-12-25 4:04 ` Barry Song
2025-12-25 10:08 ` Baolin Wang
2026-01-05 13:58 ` Brian Foster
2026-01-05 17:50 ` Matthew Wilcox
2026-01-06 3:47 ` Baolin Wang
2026-01-06 15:56 ` Brian Foster
2026-01-07 1:12 ` Baolin Wang
2026-01-06 18:46 ` Matthew Wilcox [this message]
2026-01-07 1:16 ` Baolin Wang
2025-12-28 4:29 ` Matthew Wilcox
2026-01-05 8:54 ` Baolin Wang
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