From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792685763; b=Tw7kPYUK9mrMDYoAq7w7EpCKEDtvYqthln5ZTveLFGuGhz/jQq48l/1F5NpRDznODMdj oLFQ6+vhT4RPMBSeS5cCn8RBJ1NAU1Zf1YABzRVr18IdC3OEbFBwmxfOwM65Dw9FnmEMp D8w6eQiUpgyvcAAKqgbSzEjWbMGT5Ho1rK7/wD91pnqCqRCQkCI4UDxeqOdPspj2G1IU7 H7MdrW7vj7RwSDQaPklnJkLxCJzBab4NPzUaBmjTb443hvEVXXiBP7pjAxq2cVDNCwkru oXsQwd+ZXW+IIySwinfT0kZckyUjo7XAfm53MuMUPothY3/L4wqsgKkfGUIrp0n9cXg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792685763; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=15w2lgAl32OFNxw2wcnQXe9bFvYV2hprHtzirYcVPkc=; b=fBaAWrqAT9ZH8PRfQo0UF9WAks9wO+v5CYuSfgZdUM8mtpKMNXW+XtLDUIEAzzOoxaOc htmAeYkaXlJt8NXdcvMua0XTvTJyo3d9YjLtJ7CP44toZmD4cfoYtwci6Uqhb1eGF91zb aqBM2VYZ12E1zsO9ZCOx6mrulYDzcRzTO9hQyD8+iROetvDcKpA0ABSequIERZDPv/8cP fTuStw6G49EbA3ZEQeLZmuvu59pQYHwzsQbz72OeT20xW0rd2/koEk9/MN41iPS4i9Le0 fj1oHH6z9ZK54JCaUt+4muxyTg/VVynoJJTnHxRaFJCnsmpcEkSnKMBUti+k0EUuXQw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=oALSGmNp; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 51AFE606A319 for ; Thu, 22 Oct 2026 16:16:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=oALSGmNp Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7610D1F01825; Thu, 22 Oct 2026 16:16:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792685763; bh=15w2lgAl32OFNxw2wcnQXe9bFvYV2hprHtzirYcVPkc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=oALSGmNpIJygB0Utw3g2Z2oETO1qopmveiRp4ZGsOc2RlS7/cI7hbm8A3/qZjqJOs 1nHIOJ1dgOH3hsP105b2MJ+QaYipcvGa16izO9Ys7aDFZkqEDhniC3Vdntj5eI46Nz 8Zs7Uuw0xshqkXFDgziLEhJoPdwzRqHo4OSg6+95DDhzRPGEjUopZHwX7sqqQO7Kdt cY1+trlQO7o28SoJzh5CnolN7o6gRKi/Vt0EupoMGiTvZKrMhgH/6a+vTMIiq9hsds HkIusr2XBI92luI6ju3A8s7D5L+lUXW4PSNBEJbdCs9AKKTPRO1MZWbP5zPenUdgah d7e/2L0lQHJmw== From: Sasha Levin To: stable@vger.kernel.org Cc: Yun Zhou , syzbot+837bcd54843dd6262f2f@syzkaller.appspotmail.com, Christoph Hellwig , Carlos Maiolino , Sasha Levin Subject: [PATCH 6.1.y] xfs: don't hold buffer locks across sync transaction commit in xfs_sync_sb_buf Date: Thu, 22 Oct 2026 12:16:00 -0400 Message-ID: <20261022161455.1673987-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026102121-disloyal-unaware-612c@gregkh> References: <2026102121-disloyal-unaware-612c@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Yun Zhou [ Upstream commit 41a28c865d1d5843f8cb9e0af17a8f4d9e2961ff ] xfs_sync_sb_buf() holds sb/rtsb buffer locks across a synchronous xfs_trans_commit(), which flushes the CIL push workqueue internally. If shutdown occurs during the CIL push, xfs_buf_item_unpin() needs to lock these buffers to fail them, causing a deadlock: setlabel: holds buf lock -> flush_workqueue(xfs-cil) CIL push worker: xfs_buf_item_unpin -> xfs_buf_lock(same buf) Remove the xfs_trans_bhold() calls so that commit releases the buffer locks normally. After the sync commit, re-acquire the buffers via mp->m_sb_bp / mp->m_rtsb_bp for the on-disk writeback. Fixes: f7664b31975b ("xfs: implement online get/set fs label") Reported-by: syzbot+837bcd54843dd6262f2f@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=837bcd54843dd6262f2f Cc: stable@vger.kernel.org Signed-off-by: Yun Zhou Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino [ sashal: omitted realtime superblock changes because the target code lacks that support ] Signed-off-by: Sasha Levin --- fs/xfs/libxfs/xfs_sb.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c index b5f081993cd4f..6c5c2b40056d8 100644 --- a/fs/xfs/libxfs/xfs_sb.c +++ b/fs/xfs/libxfs/xfs_sb.c @@ -1148,26 +1148,23 @@ xfs_sync_sb_buf( struct xfs_mount *mp) { struct xfs_trans *tp; - struct xfs_buf *bp; int error; error = xfs_trans_alloc(mp, &M_RES(mp)->tr_sb, 0, 0, 0, &tp); if (error) return error; - bp = xfs_trans_getsb(tp); xfs_log_sb(tp); - xfs_trans_bhold(tp, bp); xfs_trans_set_sync(tp); error = xfs_trans_commit(tp); if (error) - goto out; - /* - * write out the sb buffer to get the changes to disk - */ - error = xfs_bwrite(bp); -out: - xfs_buf_relse(bp); + return error; + + /* Re-acquire and write the sb to disk. */ + xfs_buf_lock(mp->m_sb_bp); + error = xfs_bwrite(mp->m_sb_bp); + xfs_buf_unlock(mp->m_sb_bp); + return error; } -- 2.53.0