From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F3B1B304BCB; Sat, 30 May 2026 17:50:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780163410; cv=none; b=TZOJGJLNt6ozPM55b0zHNrDhetLuzHZ4GhX9QOpHtycsHbZDKWONHVBt/3vaCSCqw7WXKq7F4WkeGsUWTKkvgP14au7Cm8KxeGyu4m9sydbMtiJ3WNOghSGJLX0+vi8kozg9wAIAU8h+JRBAwdcJlJCZTceBX2aShp75khu8tYM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780163410; c=relaxed/simple; bh=xAIol06arCDvCLu2Djml8cHUPFGSyimAD3B544xeqaU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ANkMG1c2rX4svkJk0hbBISqs8dGsR06mnrP2iLEEq/Fuxl4iJWSB+Keqp1uH+AIhb5cwbtXN7uZIKM6Ky3YVac/U3yWUQcW8HubarCsc9KTNZOaw339+nJ7kqsDttXuYndyKJQzwXGLGNdZqnVt6yJNDc153E6gvHXPxMHUfmFE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=t1I5Dt9G; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="t1I5Dt9G" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4545A1F00893; Sat, 30 May 2026 17:50:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780163408; bh=7zKlyvwaO0ydPQcYVntHWhVheR6t+Z1YJlnEOhFsi9I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=t1I5Dt9GSisSU9df5JXvSxiho13V0LZrmo7aIPsHhEg+RjoifIWcfiqDxJp9f5BaB YYL/EzP1X8IWQmB5sXtlV5X3JVgsyAm2sMYtEZrT58dCEyAIMLtYxCtsXrLEx/mJiI FjVDZ9LiVff/+6gMLTGs75EPQkQmzNQtalQe3Cbo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yiyang Chen , Balbir Singh , "Dr. Thomas Orgis" , Fan Yu , Wang Yaxin , Andrew Morton Subject: [PATCH 5.15 249/776] taskstats: set version in TGID exit notifications Date: Sat, 30 May 2026 17:59:23 +0200 Message-ID: <20260530160246.968184171@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260530160240.228940103@linuxfoundation.org> References: <20260530160240.228940103@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yiyang Chen commit 16c4f0211aaa1ec1422b11b59f64f1abe9009fc0 upstream. delay accounting started populating taskstats records with a valid version field via fill_pid() and fill_tgid(). Later, commit ad4ecbcba728 ("[PATCH] delay accounting taskstats interface send tgid once") changed the TGID exit path to send the cached signal->stats aggregate directly instead of building the outgoing record through fill_tgid(). Unlike fill_tgid(), fill_tgid_exit() only accumulates accounting data and never initializes stats->version. As a result, TGID exit notifications can reach userspace with version == 0 even though PID exit notifications and TASKSTATS_CMD_GET replies carry a valid taskstats version. This is easy to reproduce with `tools/accounting/getdelays.c`. I have a small follow-up patch for that tool which: 1. increases the receive buffer/message size so the pid+tgid combined exit notification is not dropped/truncated 2. prints `stats->version`. With that patch, the reproducer is: Terminal 1: ./getdelays -d -v -l -m 0 Terminal 2: taskset -c 0 python3 -c 'import threading,time; t=threading.Thread(target=time.sleep,args=(0.1,)); t.start(); t.join()' That produces both PID and TGID exit notifications for the same process. The PID exit record reports a valid taskstats version, while the TGID exit record reports `version 0`. This patch (of 2): Set stats->version = TASKSTATS_VERSION after copying the cached TGID aggregate into the outgoing netlink payload so all taskstats records are self-describing again. Link: https://lkml.kernel.org/r/ba83d934e59edd431b693607de573eb9ca059309.1774810498.git.cyyzero16@gmail.com Fixes: ad4ecbcba728 ("[PATCH] delay accounting taskstats interface send tgid once") Signed-off-by: Yiyang Chen Cc: Balbir Singh Cc: Dr. Thomas Orgis Cc: Fan Yu Cc: Wang Yaxin Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- kernel/taskstats.c | 1 + 1 file changed, 1 insertion(+) --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -632,6 +632,7 @@ void taskstats_exit(struct task_struct * goto err; memcpy(stats, tsk->signal->stats, sizeof(*stats)); + stats->version = TASKSTATS_VERSION; send: send_cpu_listeners(rep_skb, listeners);