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=1793826790; b=fL6YH9NlYmnXkNLdhYFUFCrxbwt2xb708SwvYuEiUvhhtgBvKURspgvyGfNIaAA14jYi 1fZKDwf65uEQzX470FbKBrXBTJJnWalt8Mammovty82N1PAEE5Ku3QVLypm3JN99VHKJz TlonU8CAEtLvppzCpJyc2LB7AKmP62gN4Y0MX38CYjjvT38sZHY8ZeelFoCFgmLog2lVk jtt6NpFID3LwCSzJeoKpwDnPN8NQQe1LKaryeYXBVPdNNd+RXDYLOJb3pSoAtFNl4GQYB 0W0JDoP60wrmYiocM4np4npHF8gUVkBJuVSQXXmYwAtEHWxRaxEeB0wPgmOKXXNivdA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793826790; 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=9DqIlOilLLn/bPvIcMs5OBYd5js16QyERUEORWcRFA0=; b=rQ60YkIemg8V6KQNVGsb87vT8E2S+oc8XmICZnPIxWN7kPSs+3ZN8Ga4CrMZXbTAmkyq wXmKo0EENo7A27AYzpXodHTylcHtlc3o9vfhStAIgiepE2kmCZCqskq8eiEmMgauu10eW IVdAAzWdVYenpTeJVQ68r+DltUjLID92Im91H8wVM78+iOquyhYB8nxkLKYaZqXYVwvQB +aQPLUhC7OKX2f1Hed3W/Sa5VgcmHGDuCoctegvq0spZ4lCk5vLdrCy0/vNlJhl9hOfrW +lGasGerbA/Dzz5eLuv83FZztFn6lu25om743tLjkSvSo83WpN206MzePMPDh6+Sbpw== 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=If1s1fBa; 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 C37506071A07; Wed, 4 Nov 2026 21:13:09 +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=If1s1fBa Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60AE01F000C1; Wed, 4 Nov 2026 21:13:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793826789; bh=9DqIlOilLLn/bPvIcMs5OBYd5js16QyERUEORWcRFA0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=If1s1fBa7Yu8B1CH7Ukiy2ikt7/EWzKg7VRwtFw6q5ICIu4+LM16wBa7Tl8ViLHHH 4mAzwwD0mmR0BLJlgJuPetPk3MRTIDgaFmsHclhIXQDDZhr3ndSe1Ay5seVjyEdZQk b2e6mjl/PeBWWp5fyDXUgbnrZVD5qvezo/Osd/LY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oleg Nesterov , Jens Axboe , "Christian Brauner (Amutable)" , Sasha Levin Subject: [PATCH 6.18 0008/1005] exec: cancel io_uring requests before de_thread() Date: Wed, 4 Nov 2026 15:55:41 -0500 Message-ID: <20261104211043.766954811@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@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: Christian Brauner [ Upstream commit b42c85c20d84ff3e4f0f027d6596c3b3b4a20657 ] 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) Signed-off-by: Sasha Levin --- fs/exec.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 4aa6905259591..3f301138e65a0 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1134,6 +1134,13 @@ 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) @@ -1150,10 +1157,6 @@ int begin_new_exec(struct linux_binprm * bprm) /* 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(); -- 2.53.0