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=1793210292; b=NCAXhJWjg9QdT6Dc8oWKPIpCfT0YpVhhGGyNNErpg1yDwyy3rjafjUQufiNJGVw7FnWB 9KxPX2CX8TtFn3ScVFZqwgioHRk++J875Tp04xapsYvd/yCK0fQbj3sROZ5Vqxb48U7QC oMluJEIVNXQzviPdPpRu52H30frg2Qbv5wKUEpSOE4iZoq19baQZa/rMVe8+ai8wfCK/e clPYXkZgHGH5fNFwQ6cjtsbMOcrlmjxn7EQb9DNZDHT1/E8Beh0DSoWmQcup5Zh+iznPo cVpzDC3J5zP8+JJpn/QdmbzijfNUQARexsZgWTS3R+2DATgPii46Uq6IQPJE7kjOQRA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210292; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=e3hQQND/8DjEoU7MtYhRdSVL13L5uqIrY3HtNTt/lDU=; b=mpVdEw+FCpVtnSeC43hXUVZ4FDNwpucg/ksd2+v16WBs7KhmNlaF+5l5jPdgplq20JgU v1Fi37zuZqTqAsmcggWgBqvXs9KAGbnXT2prLViQP3bXpZl4oZcS3XjoO0jlUsodC482/ nrcX2Q+LkQdcT0rt22np/yp7FZ75ObVDb6LWWiPFJYm93m9aCtHaFvx+NxkvbsjeOQjmh 9cTMhdqdXQRqK2V7kEkRLrYR7uo9MLP6YNMx85/2udWo0NyPOeRtN8rv1F2+9EmygXWUK 1cqL+TgS9eU/vzfk8T4pfVIS9C2VRuQ64Qfgc9XHRNL1up+f4UjUV+hS8a8lBeYiKpg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=JOEuKZEI; 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 699CF606A31C; Wed, 28 Oct 2026 17:58:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=JOEuKZEI Received: by smtp.kernel.org (Postfix) with ESMTPSA id BB2F61F01825; Wed, 28 Oct 2026 17:58:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210292; bh=e3hQQND/8DjEoU7MtYhRdSVL13L5uqIrY3HtNTt/lDU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JOEuKZEIoGHoTVJA/SACkEe5X4QJBRE7sxfOn4ZwGBKxgikH1wPAXiStv5CTaZMS2 15TR4AYkKWs+pi4vVud1e2jwPeTW3o+2qdVwXwSExaiPsoSCnZvRnkOryThgnYyuly aMjpFsMPH7ft5VzHipYjki9IriRQ/ivAWyHyPT5E= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josef Bacik , Jens Axboe Subject: [PATCH 6.6 142/168] io_uring/timeout: dont skip over reached sequences Date: Wed, 28 Oct 2026 18:01:18 +0100 Message-ID: <20261028165946.445101911@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165943.089486480@linuxfoundation.org> References: <20261028165943.089486480@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josef Bacik Commit c6c0b3eba88c3b13ca11ea112404982e86d58f7a upstream. io_flush_timeouts() copes with the wrap of the CQ sequence by looking at the distance from ->cq_last_tm_flush. That relies on the target of each pending timeout being at or ahead of the last flush. io_timeout() breaks that. It sets ->cq_last_tm_flush to the current sequence, on the assumption that nothing has been posted since the last flush. That isn't true. A multishot request posts its CQEs right when it is issued or retried, but they are committed, and the timeouts flushed, at the end of the submission or task_work run: X: IORING_OP_TIMEOUT, off == 1 target_seq == N + 1 io_submit_sqes() multishot recv, posts two CQEs sequence == N + 2 Y: IORING_OP_TIMEOUT, off == 100 ->cq_last_tm_flush = N + 2 io_flush_timeouts() X: events_needed = N + 1 - (N + 2) // 0xffffffff events_got = 0 // not yet X isn't completed although the completions it was waiting for have happened, only its timer can end it now. And as the list is sorted and the walk ends at the first timeout that isn't due, it gets in the way of the ones behind it. The insertion sort has the same problem, it measures the distance of the pending targets from the current sequence. ->cq_last_tm_flush only needs to be brought up to date if no timeout is waiting for a sequence, as io_flush_timeouts() isn't called before the first one is set up. Otherwise it is current enough. Timeouts with a sequence come first in the list, so looking at the first entry will do. Use the last flush as the base for the insertion sort as well. Fixes: f010505b78a4 ("io_uring: flush timeouts that should already have expired") Assisted-by: LLM Signed-off-by: Josef Bacik Link: https://patch.msgid.link/20261015-b4-io-uring-fixes-v1-29-c1556f5d7bf5@toxicpanda.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/timeout.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) --- a/io_uring/timeout.c +++ b/io_uring/timeout.c @@ -579,8 +579,9 @@ int io_timeout(struct io_kiocb *req, uns struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout); struct io_ring_ctx *ctx = req->ctx; struct io_timeout_data *data = req->async_data; + struct io_timeout *first; struct list_head *entry; - u32 tail, off = timeout->off; + u32 tail, base, off = timeout->off; spin_lock_irq(&ctx->timeout_lock); @@ -597,11 +598,17 @@ int io_timeout(struct io_kiocb *req, uns tail = data_race(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts); timeout->target_seq = tail + off; - /* Update the last seq here in case io_flush_timeouts() hasn't. - * This is safe because ->completion_lock is held, and submissions - * and completions are never mixed in the same ->completion_lock section. + /* + * Update the last seq here in case io_flush_timeouts() hasn't, it only + * gets called once sequences are in use. Leave it alone if there are + * timeouts waiting for one. CQEs may have been posted since the last + * flush, and a target that has been reached must not fall behind it. */ - ctx->cq_last_tm_flush = tail; + first = list_first_entry_or_null(&ctx->timeout_list, struct io_timeout, + list); + if (!first || io_is_timeout_noseq(cmd_to_io_kiocb(first))) + ctx->cq_last_tm_flush = tail; + base = ctx->cq_last_tm_flush; /* * Insertion sort, ensuring the first entry in the list is always @@ -613,8 +620,8 @@ int io_timeout(struct io_kiocb *req, uns if (io_is_timeout_noseq(nxt)) continue; - /* nxt.seq is behind @tail, otherwise would've been completed */ - if (off >= nextt->target_seq - tail) + /* no target is behind the last flush, see io_flush_timeouts() */ + if (timeout->target_seq - base >= nextt->target_seq - base) break; } add: