From patchwork Tue Dec 5 21:52:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 174211 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:bcd1:0:b0:403:3b70:6f57 with SMTP id r17csp3729628vqy; Tue, 5 Dec 2023 13:59:59 -0800 (PST) X-Google-Smtp-Source: AGHT+IHwMVkq9tySG8Yyxmqdwsid1IGZG5phkITLLxStn6LXWoA/DpWlqGB7ZGFzifR0lwp7pdM4 X-Received: by 2002:a05:6a00:178f:b0:6ce:751b:7b5a with SMTP id s15-20020a056a00178f00b006ce751b7b5amr1488416pfg.62.1701813598954; Tue, 05 Dec 2023 13:59:58 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1701813598; cv=none; d=google.com; s=arc-20160816; b=JzHVMfWJbyjEkn34El7npQKzCXVEaFcCctb/qWTqjmSjzx0f/oVJCMAxc85bRykw3G +WgLDsR58SPhUK7toi1ZPAxVBW9mJfpPaD2mU9TvlY0R3098vxcF86Ly4gZJodxUkaLi U5kgxGeQUSAlMgEMSiHzP6IcGP5DerBRWHq8GfOoiVNm9rGASIdMpB9dm1jKg88qpb/Z rF/U/ez1rr7YfkQzf/r1qnluXf6c35sBGHVLO7+Y1Yz0LBvyzEOcw8O9l6ykFA9wK0ZL FsFrhfZXMAYDUYiNdpKxfmtuanDnj9/mWE/eNaBCw28ckvzs4JSntnsmj52hNeFds5v1 Rm5w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:mime-version:references:subject:cc:to:from:date :user-agent:message-id; bh=wju4bz4ZZB5HfKXEJ3E/0DUNGAOpRCbvOj6tu97hmsA=; fh=F2250jmQaoXj9LX9jKci9w4XCpR+cJC9ffd782I0skk=; b=MK/rjKYNvCblYpe4KIim3HHaw1KIbMzZ0rIONHzGPlmJxTW1YlQHpPAlCTCCRQXyOQ +EFP1NV/1aRbc3KEqNSQARyD89RJfSoGEGBVeKTTuw62hglyUjQPgihKwSsel6yYL8Lg WJib2tb+TSl9c+f0m9Zc53687eTYcl6fHaT8FOWMKofkyPwrSQBFTdw0ObOuOwNbGFbG vb7MvBpf/IxFDEp42dTjaIz3SFJTEyNbbfRW2btAJotN542iaJO8mjDpZex8xeCdTNzZ /ryk3HsdfGm/Z4WVujVDeU2eF+CahSA9Y1Mf1/sSNWaYLmB+vfYS43dAUBngvqoe4Wvp ZmLA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from snail.vger.email (snail.vger.email. [23.128.96.37]) by mx.google.com with ESMTPS id a20-20020a056a000c9400b006cdf3e98118si874613pfv.118.2023.12.05.13.59.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Dec 2023 13:59:58 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by snail.vger.email (Postfix) with ESMTP id EF6DA80BC533; Tue, 5 Dec 2023 13:59:57 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346352AbjLEV7r (ORCPT + 99 others); Tue, 5 Dec 2023 16:59:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230106AbjLEV7m (ORCPT ); Tue, 5 Dec 2023 16:59:42 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E22ED45 for ; Tue, 5 Dec 2023 13:59:44 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BE052C433CA; Tue, 5 Dec 2023 21:59:43 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1rAdSc-00000000POI-2qad; Tue, 05 Dec 2023 17:00:10 -0500 Message-ID: <20231205220010.454662151@goodmis.org> User-Agent: quilt/0.67 Date: Tue, 05 Dec 2023 16:52:09 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org Subject: [PATCH v2 1/3] tracing: Always update snapshot buffer size References: <20231205215208.195443981@goodmis.org> MIME-Version: 1.0 X-Spam-Status: No, score=-4.0 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Tue, 05 Dec 2023 13:59:58 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1784480896473266325 X-GMAIL-MSGID: 1784480896473266325 From: "Steven Rostedt (Google)" It use to be that only the top level instance had a snapshot buffer (for latency tracers like wakeup and irqsoff). The update of the ring buffer size would check if the instance was the top level and if so, it would also update the snapshot buffer as it needs to be the same as the main buffer. Now that lower level instances also has a snapshot buffer, they too need to update their snapshot buffer sizes when the main buffer is changed, otherwise the following can be triggered: # cd /sys/kernel/tracing # echo 1500 > buffer_size_kb # mkdir instances/foo # echo irqsoff > instances/foo/current_tracer # echo 1000 > instances/foo/buffer_size_kb Produces: WARNING: CPU: 2 PID: 856 at kernel/trace/trace.c:1938 update_max_tr_single.part.0+0x27d/0x320 Which is: ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->array_buffer.buffer, cpu); if (ret == -EBUSY) { [..] } WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY); <== here That's because ring_buffer_swap_cpu() has: int ret = -EINVAL; [..] /* At least make sure the two buffers are somewhat the same */ if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) goto out; [..] out: return ret; } Instead, update all instances' snapshot buffer sizes when their main buffer size is updated. Cc: stable@vger.kernel.org Fixes: 6d9b3fa5e7f6 ("tracing: Move tracing_max_latency into trace_array") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 9aebf904ff97..231c173ec04f 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6392,8 +6392,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, return ret; #ifdef CONFIG_TRACER_MAX_TRACE - if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL) || - !tr->current_trace->use_max_tr) + if (!tr->current_trace->use_max_tr) goto out; ret = ring_buffer_resize(tr->max_buffer.buffer, size, cpu);