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b=FDAO02Mx0HtPRCxykwrJgCGrawrT62ethZkSD5daCtas+MWayyXsKOqrAWzJz7Axa 6EQLO39T6Ni5s3XCof88Rz9MRzs1kJhNr37Xx+nRCElWDvpV4tFMGRSnWP4R3VMSPG 07a8eUb8kI+owgL+H4a53NrGsc9z1qRfLTKGFM/s= Date: Sun, 20 Sep 2026 13:04:33 -0700 From: Andrew Morton To: David Carlier Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, kasong@tencent.com, bhe@redhat.com, chrisl@kernel.org, baohua@kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, hughd@google.com, baolin.wang@linux.alibaba.com, syzbot+23b25ba3c6bf971f9c57@syzkaller.appspotmail.com Subject: Re: [PATCH] mm/shmem: don't release a swapin-error marker as a swap entry Message-Id: <20260920130433.7c68761144a2a63e2ce32bb4@linux-foundation.org> In-Reply-To: <20260920155002.1030454-1-devnexen@gmail.com> References: <20260920155002.1030454-1-devnexen@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: ugyxk9f9b6k5fwpq746iyfedj9ycsawt X-Rspamd-Queue-Id: 9BC7520009 X-HE-Tag: 1789934675-767919 X-HE-Meta: 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 KayWCrgR 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, 20 Sep 2026 16:50:02 +0100 David Carlier wrote: > A failed shmem swapin from -EIO, for example. > frees the swap slot and leaves a PTE_MARKER_POISONED > entry in the page cache. On truncate or eviction shmem_free_swap() passes > that marker to swap_put_entries_direct(), which warns because it is not a > swap entry. There is nothing left to release either way. > > Skip the release for non-swap entries, as every other caller already does. > > Reported-by: syzbot+23b25ba3c6bf971f9c57@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=23b25ba3c6bf971f9c57 > Fixes: ac2d3268284b ("mm/swapfile.c: remove the unneeded checking") > Signed-off-by: David Carlier I guess we should backport - errors can happen and WARN can crash machines. What do others think?