From patchwork Wed Jun 30 00:34:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Burton X-Patchwork-Id: 469498 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE82CC11F67 for ; Wed, 30 Jun 2021 00:34:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF9D761CF7 for ; Wed, 30 Jun 2021 00:34:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235642AbhF3Agu (ORCPT ); Tue, 29 Jun 2021 20:36:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38772 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235594AbhF3Agt (ORCPT ); Tue, 29 Jun 2021 20:36:49 -0400 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0F97C061760 for ; Tue, 29 Jun 2021 17:34:21 -0700 (PDT) Received: by mail-qv1-xf49.google.com with SMTP id 5-20020ad45b850000b02902986d9b7d2fso193612qvp.15 for ; Tue, 29 Jun 2021 17:34:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=2XuTKmc5MiUcD3IttpZN1adwmf1E7UnKBnnfEh9asIE=; b=S4++qrlNREHISaDmUEHXPnvjr5JNiG3QxU1bd+U22BonKWasfFWISE4WFqMwbiGsro 6FV0Vigj6cEo/YqiKaKGHFuTi5/GP3dFtgMn8pensTVybHIYMx5SCT98p5ax0lbpG6Lv NLmuLCLzBfMKL7t9zvocmdamq68VheY3xHWzI21GwZdQb99+LfuVabJayksQua8TW3Cd 14UhcfOX2pvTuJ3r3FkM1pLZhRd6msii8QkXPNiy6ONLo0oq9zoDuChUl1OwHfr6QVgY mHG2dkeQUKtw6xd8Vd1/hGT5WHOVtb5J89HVi2MDGVsZJw4iByvzvejICUUp+Gki6hg/ FX0w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=2XuTKmc5MiUcD3IttpZN1adwmf1E7UnKBnnfEh9asIE=; b=Urw/EeI+PGeXBJFbqmk+RY8dS9BbR1mPon2uHopfwqeD9Ld0lJg6r9oefGpxKaHr+Y vt1HBHiRZrUWjYOWEQdyxS9gV5NCL9uaFcosocwO1gtcY0zbydjx6XArXI5pFiPZbDJG 17x9GUgrbTO/3jxZEbbmW2gDQpxXRq5f1caDjJ8fVCm7sRaAxXnLMj9Pe+7YZHJa14FI Yq3KWXF/Z89+ZXc+sIgxeiAMN0XxN+aJM518vXhlUcoWWR8QVEuwHNGFYj99uKAY88up 5uu0aPggtzsZe8pqGk/KrHMwqkQfcYIq/fI+DmZMUGcmeFazt6PbIo7SPnnr6qMiP2sm Pxlw== X-Gm-Message-State: AOAM5305xiJZj2iHK83ROEMlfg83I+FT8Owg12dyXLY5w06hJ7GL7wxs sqIccJnqy6wpUibLONOQmw3R/aqvao56OeR8 X-Google-Smtp-Source: ABdhPJxYfIl/RsKi8Q1Y3mmzLWSHsPkK3ATLJmVUt286PIPfoCoSEuWaEF6ttquZPkAXgO/wXL2J9ADhN52OnMoR X-Received: from paulburton.mtv.corp.google.com ([2620:15c:280:201:1517:9bca:ad4d:3b49]) (user=paulburton job=sendgmr) by 2002:a0c:f885:: with SMTP id u5mr34153484qvn.28.1625013260689; Tue, 29 Jun 2021 17:34:20 -0700 (PDT) Date: Tue, 29 Jun 2021 17:34:06 -0700 In-Reply-To: <20210630003406.4013668-1-paulburton@google.com> Message-Id: <20210630003406.4013668-2-paulburton@google.com> Mime-Version: 1.0 References: <20210630003406.4013668-1-paulburton@google.com> X-Mailer: git-send-email 2.32.0.93.g670b81a890-goog Subject: [PATCH 2/2] tracing: Resize tgid_map to PID_MAX_LIMIT, not PID_MAX_DEFAULT From: Paul Burton To: linux-kernel@vger.kernel.org Cc: Paul Burton , Steven Rostedt , Ingo Molnar , Joel Fernandes , stable@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Currently tgid_map is sized at PID_MAX_DEFAULT entries, which means that on systems where pid_max is configured higher than PID_MAX_DEFAULT the ftrace record-tgid option doesn't work so well. Any tasks with PIDs higher than PID_MAX_DEFAULT are simply not recorded in tgid_map, and don't show up in the saved_tgids file. In particular since systemd v243 & above configure pid_max to its highest possible 1<<22 value by default on 64 bit systems this renders the record-tgids option of little use. Increase the size of tgid_map to PID_MAX_LIMIT instead, allowing it to cover the full range of PIDs up to the maximum value of pid_max. On 64 bit systems this will increase the size of tgid_map from 256KiB to 16MiB. Whilst this 64x increase in memory overhead sounds significant 64 bit systems are presumably best placed to accommodate it, and since tgid_map is only allocated when the record-tgid option is actually used presumably the user would rather it spends sufficient memory to actually record the tgids they expect. The size of tgid_map will also increase for CONFIG_BASE_SMALL=y configurations, but these seem unlikely to be systems upon which people are running ftrace with record-tgid anyway. Signed-off-by: Paul Burton Fixes: d914ba37d714 ("tracing: Add support for recording tgid of tasks") Cc: Steven Rostedt Cc: Ingo Molnar Cc: Joel Fernandes Cc: --- kernel/trace/trace.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 9570667310bcc..c893c0c2754f8 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2460,7 +2460,7 @@ void trace_find_cmdline(int pid, char comm[]) int trace_find_tgid(int pid) { - if (unlikely(!tgid_map || !pid || pid > PID_MAX_DEFAULT)) + if (unlikely(!tgid_map || !pid || pid > PID_MAX_LIMIT)) return 0; return tgid_map[pid]; @@ -2472,7 +2472,7 @@ static int trace_save_tgid(struct task_struct *tsk) if (!tsk->pid) return 1; - if (unlikely(!tgid_map || tsk->pid > PID_MAX_DEFAULT)) + if (unlikely(!tgid_map || tsk->pid > PID_MAX_LIMIT)) return 0; tgid_map[tsk->pid] = tsk->tgid; @@ -5194,7 +5194,7 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled) if (mask == TRACE_ITER_RECORD_TGID) { if (!tgid_map) - tgid_map = kvcalloc(PID_MAX_DEFAULT + 1, + tgid_map = kvcalloc(PID_MAX_LIMIT + 1, sizeof(*tgid_map), GFP_KERNEL); if (!tgid_map) { @@ -5610,7 +5610,7 @@ static void *saved_tgids_next(struct seq_file *m, void *v, loff_t *pos) { int pid = ++(*pos); - if (pid > PID_MAX_DEFAULT) + if (pid > PID_MAX_LIMIT) return NULL; return &tgid_map[pid]; @@ -5618,7 +5618,7 @@ static void *saved_tgids_next(struct seq_file *m, void *v, loff_t *pos) static void *saved_tgids_start(struct seq_file *m, loff_t *pos) { - if (!tgid_map || *pos > PID_MAX_DEFAULT) + if (!tgid_map || *pos > PID_MAX_LIMIT) return NULL; return &tgid_map[*pos];