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=1794590028; b=b8e2dR0VIC87OIQJ/edu5xsH+uY2lhI9kEHqF5dPyfkTvIewHowArJr9JJtQphyY3Nyc aL7XU4GKtQpuRfXmeF5f4BAVqiVCMRFQoKoUjYdyoFo8vEs3jXq2khnbfmucTRPgEvKHd kM+owTg2jMAO84OAHKGJLvLbEvDchrcIYHVTz5cS++wP9CMStyCx2hIBbfQDPuG/QvzqR 83KSPIGavy9kdYSjK92io8wmWN/dSiBs0kZxnn1yxg17aP9bPJPntA6Pe1INTGq2klGEc eUi3klZHi6ADbqTuxOoFSGAsjLjJiIKO1E+YmFEoOE8yR0/8YiQNDhXLh4Sm6zbETQQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794590028; 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-Type:Content-Transfer-Encoding; bh=KCmEWRrMxEdh0XwbSbrpZuB40RVnk1l3oz7IFjqtbvM=; b=sNduBRmHKVqFdyeqBf+lNJ5QNed+BkH+MzUWRIL3JXlWKNQmXoo7CtCoV2vQXeESIMVp 6WEFL1P56rw2RrHlFLpZULCGWlYPfJo6XSkBcaskXKspcF/nHScOK5uQ2jrxn/XsUfsji CYwsnvd6oMMkN+xAh6stID/eAVFzl8vFY0gbm7V81y/c/VWAwmTUZNmVdYl8ppDvDgjrm 6hPXCgaU2gIIQJmOS33eNjfOOEukZcch0AfI9SpnF1NKLc7WCpJlc3isFQOEKMmrCBPZy 7HIRpDnLSOBsyQ9VS/HI+FEiqXhwLyem5gLYfVsAeDEdPcXkjgq0ArIEpCfE6L0dD9Q== 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=ruKGSb4m; 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 B190360A3804; Fri, 13 Nov 2026 17:13:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=ruKGSb4m Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E3CE1F000C4; Fri, 13 Nov 2026 17:13:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794590028; bh=KCmEWRrMxEdh0XwbSbrpZuB40RVnk1l3oz7IFjqtbvM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ruKGSb4mRUPZeeN37jqIQF/m0zo56mYB1UEOBQx1WNL2VF3ApnPgFdJq7222SV4AJ TmztAj3L9mWzUB3HvXZDq4GnJpXFuOTydcozyTmq7bhQ4lxeIAJR8BL5vKo0LRbGAB KvvH6rUPso+BNg4i/71zMsuXONFkcpuwrvuOVkPo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Luk=C3=A1=C5=A1=20Lalinsk=C3=BD?= , Jens Axboe , Sasha Levin Subject: [PATCH 6.18 067/686] io_uring/poll: dont poll a writer for urgent data Date: Fri, 13 Nov 2026 10:43:20 -0500 Message-ID: <20261113153823.196961226@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153820.902362109@linuxfoundation.org> References: <20261113153820.902362109@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jens Axboe Commit edeac4546a71b6c1db4ba006a2dbf7c863f54e9a upstream. io_arm_poll_handler() starts the mask of every async poll with EPOLLPRI, for a reader and a writer alike. A TCP socket reports EPOLLPRI for as long as urgent data sits unread, so once the peer has sent a byte with MSG_OOB, the async poll of a send that waits for buffer space is ready on every re-arm. The request spins through task_work and __io_arm_poll_handler() until APOLL_MAX_RETRY is used up and io-wq takes it, the same spin that EPOLLRDHUP caused for a half-closed peer. While it spins, the request is neither in the poll hash nor in io-wq. A cancel issued right after the send gets -ENOENT and the send stays pending, until a later cancel finds it in io-wq. Only add EPOLLPRI for polls that want to read. Urgent data is an event for a recv, not for a writer. Fixes: d7718a9d25a6 ("io_uring: use poll driven retry for files that support it") Reported-by: Lukáš Lalinský Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- io_uring/poll.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/io_uring/poll.c b/io_uring/poll.c index 3239bc3039fb3..2594c1f04e705 100644 --- a/io_uring/poll.c +++ b/io_uring/poll.c @@ -736,7 +736,7 @@ int io_arm_apoll(struct io_kiocb *req, unsigned issue_flags, __poll_t mask) int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags) { const struct io_issue_def *def = &io_issue_defs[req->opcode]; - __poll_t mask = POLLPRI | POLLERR; + __poll_t mask = EPOLLERR; if (!def->pollin && !def->pollout) return IO_APOLL_ABORTED; @@ -744,7 +744,8 @@ int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags) return IO_APOLL_ABORTED; if (def->pollin) { - mask |= EPOLLIN | EPOLLRDNORM; + /* urgent data is an event for a reader only */ + mask |= EPOLLIN | EPOLLRDNORM | EPOLLPRI; /* If reading from MSG_ERRQUEUE using recvmsg, ignore POLLIN */ if (req->flags & REQ_F_CLEAR_POLLIN) -- 2.53.0