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=1793201843; b=TT+AYCdAnkPYfv4SoOW/YjSnoiAR7x2cTh98C+5BsCF5oQ7B7UC6Be+skEVvAbPeSDST LnpFCoFUc9J+kTLMBGGdAYrZiKvCXmakWjtl94fe6OPYTEO4D3xOoWBFljW/DXp6kntMY pAxFdHWDMav8xyKxwAs21ISk3PgmMBZ698JwYCoHms0lhLMvEpw9TiJUWRxOyi6eNQDtD KeufyrnxH5ixpIG0ZvGoyKAhJgVAvD1T4g1te7CmbOUrAe4UCcibtGL2up01rvUCz33P8 4vs8dGBLaLYMmTbIcPOkA+mT/ewGipVirSOH6327F22bJ2p4LnOvtaCuH197Y8REGaQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793201843; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=Y033NXx+ZJ81bnbiYCYsUpj/r8id/IoCvlBFVueduDM=; b=HzBkNQ6sRlpObNovuwM12HHgTT+mGJ1CmsKjEaFeaVWPyL7+R/JlJRF6+dgxLQhSIqUm /jlDPFY8C00YQW5YAD5S3Tjnqu6Bljb5swFlTS5B0ScnLukDbVNsKqzmiIblNqBh9+0QQ sMxyCUal0QMoySgHsmlR1pRSXrnacPTzDaLANQmc8U7bmlFf73/bH6b66JMUgvcYYuA1d GcamN+M2k3bUAD74SSw/p8YfwtbB3S29pnHP3A9pAQ5finSd2h8Q7w/wmWUXtIRXcqsOw DV0bx4OHubiUhbOqzcJMzu2Tc6/4SP77a0e0eCQNkmuH350KggvZDcdK/Zc01ksELpg== 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=SbBPyEgI; 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 0E23B606A31F for ; Wed, 28 Oct 2026 15:37:23 +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=SbBPyEgI Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53EBD1F01825; Wed, 28 Oct 2026 15:37:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793201842; bh=Y033NXx+ZJ81bnbiYCYsUpj/r8id/IoCvlBFVueduDM=; h=Subject:To:Cc:From:Date; b=SbBPyEgIdtIG1Gaoo6/zoz9buqXQsCYt7+OnolEmwmmKjnrHNmo8PqCFNV87V/iej cc8PUgdUF1hGyEAFUDILrrB4r2X39CmvvDhYXnwbktBJX42VTo3FV8DI17PpKo+sQl NadMfgrjL7pTUik5YCzO0oSNHm40NMLGG7QzmaPE= Subject: FAILED: patch "[PATCH] exec: cancel io_uring requests before de_thread()" failed to apply to 7.2-stable tree To: brauner@kernel.org,axboe@kernel.dk,oleg@redhat.com Cc: From: Date: Wed, 28 Oct 2026 16:37:18 +0100 Message-ID: <2026102818-halt-spruce-26fc@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 7.2-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-7.2.y git checkout FETCH_HEAD git cherry-pick -x b42c85c20d84ff3e4f0f027d6596c3b3b4a20657 # git commit -s git send-email --to '' --in-reply-to '2026102818-halt-spruce-26fc@gregkh' --subject-prefix 'PATCH 7.2.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();