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=1793201857; b=eywgP5GFWWy6/5u82nB7eLd6MVmc3vrp2BNpRXDxkIYWMLSg1/eIhBqduzPDytPC36VP rzGvKzCIK+HWkZ5IqOZyC+siNcCIma67Nu6ofazr5Er8F5WMUuYAA8BbI1X9by1C+TNIc i6+pY8sQfJ0ThwznXQ5v29+Sft/B/oxZs5vwY1biokqxFdn5iDDP1BD5oFluQ0fcqP89d mrcv4hKEiGUCUJVwZUpBM67PzaUkJWNOaUd06EZPCAQLvzGBvg+T3J8BO2xW+EwoMp4v4 ZQ/l4qWylnN8RMsgG14AsrukSCRYrCtNaxS+vAaXBlTWiSwFOu+RMlbygRTa75x16WQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793201857; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=SiW4B/Bly/gkxkXkOO4F3D6Ws9SnXckzMrJ/um4jy7Y=; b=kVUgOh8bOG+MFd+plGgKaqdmA6jpvJkPL1FUriuBvIyH780i+5M9ShjE1o37JknkbcLo iq4qkJv43900eMo7HXjdCiao2XzBI/rJAN0m9r9/cL8UlkpfGlbmdzuQThby7B/ZQcn0L 23LGjjj+WMAt7IA+OT/jdsqP/BJDIIROe2W2ky1GRdRS1/H4UePwI+VRoYmMCsXfVk3WZ mlYMS7OwcOuGkZv4b0FiFjtMLjLpFISETC0HTne5m/2vSYnUPBUkeVlBFYw2/54Fe5JTN 3cPzJCvfgqjeiBJCjPizvw4TQlgYiBPsM5NRXQg5GNrDqJv5tdAmaoDh/ErZkkVnp2g== 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=aCuIduu3; 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 73ECB60A2604 for ; Wed, 28 Oct 2026 15:37:37 +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=aCuIduu3 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 869D71F031E2; Wed, 28 Oct 2026 15:37:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793201857; bh=SiW4B/Bly/gkxkXkOO4F3D6Ws9SnXckzMrJ/um4jy7Y=; h=Subject:To:Cc:From:Date; b=aCuIduu36QBMYGKH5vn3fYpxuiqLdCG3M/Jh2rGn5LzvkEhnTcOHBqHCfXrAtBatX F0PDSRzs+ywoHdF7DTZoTX+46tImiDL1QJ/KzeSAYyofmdtGmCtpa7IViexcnL1QcY 8/6NFDuZyWWEa8Y/5EMAuI8BNn3ITFDv3/XxY7AA= Subject: FAILED: patch "[PATCH] exec: cancel io_uring requests before de_thread()" failed to apply to 5.15-stable tree To: brauner@kernel.org,axboe@kernel.dk,oleg@redhat.com Cc: From: Date: Wed, 28 Oct 2026 16:37:21 +0100 Message-ID: <2026102821-deluge-generic-8319@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-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x b42c85c20d84ff3e4f0f027d6596c3b3b4a20657 # git commit -s git send-email --to '' --in-reply-to '2026102821-deluge-generic-8319@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From b42c85c20d84ff3e4f0f027d6596c3b3b4a20657 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Mon, 21 Sep 2026 15:45:01 +0200 Subject: [PATCH] exec: cancel io_uring requests before de_thread() begin_new_exec() cancels the exec'ing thread's io_uring requests after de_thread() made it the only thread in the thread-group. Now io_uring_task_cancel() runs task work after. If it runs a create_worker_cb() item then a io-wq queued on the thread before the exec creates a new io-wq worker thread. Said thread joins the thread-group which de_thread() just took down. The io-iwq sticks around until it notices that its workqueue is dying. But code after de_thread() relies on being single-threaded. Move io_uring_task_cancel() before de_thread() but behind the point of no return. Any worker created during task work run from io_uring_task_cancel() is just a sibling thread that de_thread() will take down and reap. Once io_uring_task_cancel() returned the thread has neither a task context nor a workqueue left so nothing can add a thread behind de_thread()'s back anymore. Suggested-by: Oleg Nesterov Link: https://lore.kernel.org/r/aq0_lvHDViIpX_Mu@redhat.com Fixes: 3bfe6106693b ("io-wq: fork worker threads from original task") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260921-work-coredump-fixes-v3-12-8e4adb1619e6@kernel.org Acked-by: Oleg Nesterov Reviewed-by: Jens Axboe Signed-off-by: Christian Brauner (Amutable) diff --git a/fs/exec.c b/fs/exec.c index 745f6eb5279e..bf143ee3acb1 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1148,16 +1148,19 @@ int begin_new_exec(struct linux_binprm * bprm) */ bprm->point_of_no_return = true; + /* + * Cancel any io_uring activity across execve. This runs task work + * that may still create an io-wq worker, so do it while de_thread() + * can still zap it. + */ + io_uring_task_cancel(); + /* Make this the only thread in the thread group */ retval = de_thread(me); if (retval) goto out; /* see the comment in check_unsafe_exec() */ current->fs->in_exec = 0; - /* - * Cancel any io_uring activity across execve - */ - io_uring_task_cancel(); /* Ensure the files table is not shared. */ retval = unshare_files();