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=1793218415; b=EyUrbggVFqWioIAF5SnqZcIzvt2ZQDAipnKzYwbilQ4dBMfBOWX2B0wz6h5T8EYQ1nNV 2i18rSC7z0LOsCl8AlplVpLSKgL2HYp19zvod8mPgvEdeUtpmRzz12Yje6hUGo8JiApyI /THcFOytR+b0y5Yy+B1vuycFqFJtA4QcqGVPBbRfiU5JGFSegc58z/p0Srdy+4kKhR0aP +v1MmBum/HKSU6Y+KdmtIXGoFzdNvc60lJZsBRnuOGWo8CgBGCL7qgtRxFoUj9U5EcH/I NwtjRjM1viFOxXboS/sI16Sd6fq7hGMF2LkDV3Xt/8XjMhZYoJJQU1MCZEvgodXf4TQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793218415; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=FxrjgfXmb0WFPqD0MLL3SKSNt9ImyVAxft9uZqXlK7Y=; b=FCKuejcYlV+xnxgcrQqaCF+MDoXYrVFNmzcNzyh3DnG8BYy3Fj9RtvIPZvCO+lit+RSq M0G3jfG+A5RIWuf9UuLvc6ndAkkJ94SeNjKl23kyt2zJZea2LO4bwYuKEl+doWaV92JOx eJXgXMhffJzCpMuai2V8Ap4gEgXHDlPfv0iAaKn+t+bZ6jMyyuF8eAzKp0ucSTwawDfo5 +vi5wfHVtp9/FXKiN/twcA6Ltid5aPTM09PhHKk1fd3bGr2yNzmBhzf63IEM/J2vMAPEO Ag7Oc8R6XRg33C2AnpMgfQRED98lJCyOqBHWLg+0iwJhJs43lFBwmDIyNO8Mks4VUbQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=FernHeF6; 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 4BFEA606A31A for ; Wed, 28 Oct 2026 20:13:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=FernHeF6 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 544101F01825; Wed, 28 Oct 2026 20:13:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793218414; bh=FxrjgfXmb0WFPqD0MLL3SKSNt9ImyVAxft9uZqXlK7Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=FernHeF6QGO7frZjhqQMSf8vJe4pZu9+kWRxFzVTFnBezVSJ3PaA6UEOE28RPFgcx BI/dLXgU5npu5IaWrAg1T4/F8UXyG8Jk//XLeVD5tfPIXs9foSnLPyq3IOZ+mHWo7i +k8Ox8K8SvhT0fDNS9cx6t+T3fZK+/yCBRvXifeoj7fQqL39liG27KpnjV6W8DmhBV Jd4B8PZkO9WzZa+TV24kftG0hTY6CRH3sqlyupAbCvAR+hCBSkgVt55pm06QNfIbzv hi/iX8N0rm7+xb35vx3x5pZRu02uFMfKxo4EcRr/1OQUVP9YVy2LY4MH0ktP4dpOdH xQb+QA2VESBqA== From: Sasha Levin To: stable@vger.kernel.org Cc: Christian Brauner , Oleg Nesterov , Jens Axboe , Sasha Levin Subject: [PATCH 6.12.y] exec: cancel io_uring requests before de_thread() Date: Wed, 28 Oct 2026 16:13:33 -0400 Message-ID: <20261028201322.2122828-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026102819-flick-landless-21e4@gregkh> References: <2026102819-flick-landless-21e4@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-Transfer-Encoding: 8bit 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 829c74c7690d8..3c84578f48db0 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1257,6 +1257,13 @@ 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) @@ -1273,10 +1280,6 @@ 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