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=1793209759; b=CH7JxygGld/On4c2Tr62jI4JYmf3xsxknPh+/iuD+VYTdoq1LyKpc1Gf1YyQIqZT/Ag6 H1S8h7EpHKQoOctt63NwePDNElt7uxVpu38RCffy8XoEZbJHvOoHmLZ/c05moL05vTwdb MjGlV3pOgjjzDQ626HX6l5AdiyL8/UncjL+BztJp+kn1JXyIhzK55kAckIuX2wB438XER /WTbiqhB7w5O2qW/or1dVXNCrLyMzHYWjR/yboplHfSpHoBjbb5dL0hEJ3oLivTO3Zo9p bP6STD9GGLWEp3JGC56Y1c1A6YVDH2NG2+kmsrCuKxM853OHCFoYv2A2PCwtBZYp4CA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793209759; 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=w/+peoWYMIAnT0au5P6C/oRnYEVMHTRST5GsWtooc/o=; b=hNtePnDGEGofw6OZSYes0EPBR/XdnHYyQg6ZywBwePImbtwar0qTKTIjZKrf9lVtQGmG MDSgvfV1ZClWy7ldbKGCeOqk5UWjQ8uurfPzzAb8wNe2lu9E+JDMIyWYzXrRUz4kiUW5m eenlP3VfURvmsD1dTJH9/jOiWv3/SeaahtnQnixXLpDSNzc9LJVG9BKCWIIitxawhuazr ibPOZvbNc+KvYJz57vrD3sOdjE3Hq4r0KBi6AFMZveYHw7pQgyWGukhOdY/Yzlyc7/Cj2 48ZlbcLNXe3N/wvj2drPn7k9Na7PGXyUJmAj84XV16sHwjHRTSSznVeCHrkEMIjmP4Q== 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=NAMWR6XD; 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 73C70606A337; Wed, 28 Oct 2026 17:49:19 +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=NAMWR6XD Received: by smtp.kernel.org (Postfix) with ESMTPSA id C626B1F01825; Wed, 28 Oct 2026 17:49:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793209759; bh=w/+peoWYMIAnT0au5P6C/oRnYEVMHTRST5GsWtooc/o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=NAMWR6XDNDXKyoK/VDincYhB/C8ceJDFu1Nyo/m/uAt00Rl18oKC5+D3T4BnkwRAx Gq2T/nR1Dx1c4LL34DFdy+UfgT8HKy86GMUxwre1n6L+AIpcEjIxoUNl4T7NUG+ZN0 CgHNIGM9qmFY14nYtnpumTY5PXyBVBs/F1O20aew= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josef Bacik , Jens Axboe Subject: [PATCH 6.18 067/109] io_uring/timeout: dont skip over reached sequences Date: Wed, 28 Oct 2026 18:00:51 +0100 Message-ID: <20261028165943.935826917@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165942.357251485@linuxfoundation.org> References: <20261028165942.357251485@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 6.18-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 @@ -601,8 +601,9 @@ 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; raw_spin_lock_irq(&ctx->timeout_lock); @@ -619,11 +620,17 @@ 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 @@ -635,8 +642,8 @@ 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: