From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CB31C39B971; Fri, 15 May 2026 16:03:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778860996; cv=none; b=C/KD3ElXaaMWRfZB2RHO+/gp9hnDFF2MID/wXGVSANPEt1mhCBqvpdBG4Zss5yf7YSSOznmkjSLbQFT2b/36gUAPQxVdJnUjqKgg57HFtM+I1jtk1/pxOORGd9K8gpTQBj3AzWpQQ9r1CogmVMSVHjfi5TBsL6KVwoQDhe1DTpQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778860996; c=relaxed/simple; bh=nkVj8h8TX4OyOsqXpItAGAT6X99SbXG7zfeykacWsvQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AFrzCtAb7LF/jnd+KW2G2q80Wt7Zd29ANDaoZ9fRJqWu/tSlXgTQ52rCengrXz8fRkwMZaIcKskTGeNNPpRZkIfRXB7iQTYoE9YrPMs4faRQuvrZFoZzf6kXv8xfb+ftIiZM/otVDw7cc3UelcZdKGs5+rTJYQWxwDn25jrupI4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CktbtoVV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CktbtoVV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F337C2BCB0; Fri, 15 May 2026 16:03:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778860996; bh=nkVj8h8TX4OyOsqXpItAGAT6X99SbXG7zfeykacWsvQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CktbtoVVKmDBpyJwInP4dAdkKalNBZRWzB1RysROwbXGU3+cB7+FIVDiL91WNv+9X wyCryQWdGugHtMU8uSztFQr0OoeCMOs9Au8BehpklD03sM5EpmktFxUwB17sTk02JO pMfHuw8jiJs+JrlruY+erRqVn0g3Jh/1WLo1U0Oo= 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 6.6 117/474] taskstats: set version in TGID exit notifications Date: Fri, 15 May 2026 17:43:46 +0200 Message-ID: <20260515154717.569562923@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260515154715.053014143@linuxfoundation.org> References: <20260515154715.053014143@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-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 @@ -656,6 +656,7 @@ 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);