From patchwork Thu Oct 21 03:46:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yafang Shao X-Patchwork-Id: 12573775 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48A50C43217 for ; Thu, 21 Oct 2021 03:47:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3228461186 for ; Thu, 21 Oct 2021 03:47:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231882AbhJUDty (ORCPT ); Wed, 20 Oct 2021 23:49:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34246 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231424AbhJUDtY (ORCPT ); Wed, 20 Oct 2021 23:49:24 -0400 Received: from mail-pg1-x52f.google.com (mail-pg1-x52f.google.com [IPv6:2607:f8b0:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DDFB9C061753; Wed, 20 Oct 2021 20:46:18 -0700 (PDT) Received: by mail-pg1-x52f.google.com with SMTP id r2so24361012pgl.10; Wed, 20 Oct 2021 20:46:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Mg/W5W6l0pcytUDlQ1aNCJcnr1/VYvxAUJDYpkY9L/c=; b=nCBNOEdF81o2V/ZOVUdV514sp3NllC5LbtK99UBMXWooz5rjDlFETHpYTA8A8T88Ip tAQjqAfaNMXWgtSyT+9Lje7Sn6b/fM6dUq96+o8dZ6TEn+3fpaggTvmtiO1ptoCNfgw+ manf4GP+UAzTMRty33VBcUTjT6fxv2Xfusd7xEWkaShtHDiiTZ+OgCuVcCLaZDPYnhig YQFosMyYmS+c3bfNM/Y/F+aoj9wESBVhLNcV4mRJ3Wv1OuxxPQJDbga588ePtif5m3KI QT68h9quKWtAvhhjk2DwlXE7M3Zvj6Vxbhf4F3KyOiAEpX+Wk/Wr6LvMD2TrccAaHZjq JPKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Mg/W5W6l0pcytUDlQ1aNCJcnr1/VYvxAUJDYpkY9L/c=; b=m8EsTHcWtPm9nsIlZ9TaVxwdDb+x7Gm1qD3mVrugivc1OwSdwXkFfABM2n+//Hbmp9 kSRpWWA8bUWg+PNJs2FmZVxQNI1JF/NNFSf3DzIria6Da3WjViMRUO8OsVp9dRldjCds F8Qr2+/JBXniN6q681szsKnnU/dyyp8BZAbmionzFjK0rtQU/yRfjW167FKuUtsD26z7 T6y7mLikcODPm7tQiO9yolECChFfngJkMY5IUVm6QYZIKWUKLwvsTdvX0CmZEY+zfuyQ CDlINzjmc/vGyHYVX+xmkcT2HPfntGveYWFrJjP2EDOoYM1q4wgWjMx4M7zsIfSg82xS /9Yg== X-Gm-Message-State: AOAM531dRpDTcoFv/BB0E3T9NAGtO7/3YLWN7sbbh6YY6vobIE6BDuad P3g2qtgEmoCzZcnV+rS2uks= X-Google-Smtp-Source: ABdhPJw5Fj3ty7sa//4egXRyvTSsUWdMNkokVd4ZY+8Yz400yvz6Ngl1ciRpem81fOw6ilYWzxyVRQ== X-Received: by 2002:a05:6a00:23d6:b0:44d:8426:e2bb with SMTP id g22-20020a056a0023d600b0044d8426e2bbmr2824167pfc.30.1634787978484; Wed, 20 Oct 2021 20:46:18 -0700 (PDT) Received: from localhost.localdomain ([140.82.17.67]) by smtp.gmail.com with ESMTPSA id r25sm3454254pge.61.2021.10.20.20.46.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Oct 2021 20:46:17 -0700 (PDT) From: Yafang Shao To: keescook@chromium.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, arnaldo.melo@gmail.com, pmladek@suse.com, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, valentin.schneider@arm.com, qiang.zhang@windriver.com, robdclark@chromium.org, christian@brauner.io, dietmar.eggemann@arm.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, davem@davemloft.net, kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, oliver.sang@intel.com, lkp@intel.com, Yafang Shao Subject: [PATCH v5 15/15] kernel/kthread: show a warning if kthread's comm is truncated Date: Thu, 21 Oct 2021 03:46:03 +0000 Message-Id: <20211021034603.4458-6-laoar.shao@gmail.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20211021034603.4458-1-laoar.shao@gmail.com> References: <20211021034603.4458-1-laoar.shao@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Show a warning if task comm is truncated. Below is the result of my test case: truncated kthread comm:I-am-a-kthread-with-lon, pid:14 by 6 characters Suggested-by: Petr Mladek Signed-off-by: Yafang Shao Reviewed-by: Kees Cook Cc: Mathieu Desnoyers Cc: Arnaldo Carvalho de Melo Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Al Viro Cc: Petr Mladek --- kernel/kthread.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/kthread.c b/kernel/kthread.c index 5b37a8567168..46b924c92078 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -399,12 +399,17 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), if (!IS_ERR(task)) { static const struct sched_param param = { .sched_priority = 0 }; char name[TASK_COMM_LEN]; + int len; /* * task is already visible to other tasks, so updating * COMM must be protected. */ - vsnprintf(name, sizeof(name), namefmt, args); + len = vsnprintf(name, sizeof(name), namefmt, args); + if (len >= TASK_COMM_LEN) { + pr_warn("truncated kthread comm:%s, pid:%d by %d characters\n", + name, task->pid, len - TASK_COMM_LEN + 1); + } set_task_comm(task, name); /* * root may have changed our (kthreadd's) priority or CPU mask.