From patchwork Thu Sep 9 03:13:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?546L6LSH?= X-Patchwork-Id: 509130 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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_SANE_1 autolearn=unavailable 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 1D816C4332F for ; Thu, 9 Sep 2021 03:13:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 00D6A61178 for ; Thu, 9 Sep 2021 03:13:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350027AbhIIDOi (ORCPT ); Wed, 8 Sep 2021 23:14:38 -0400 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:56809 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349225AbhIIDOd (ORCPT ); Wed, 8 Sep 2021 23:14:33 -0400 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R171e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04394; MF=yun.wang@linux.alibaba.com; NM=1; PH=DS; RN=19; SR=0; TI=SMTPD_---0UnkWDai_1631157201; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UnkWDai_1631157201) by smtp.aliyun-inc.com(127.0.0.1); Thu, 09 Sep 2021 11:13:22 +0800 To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "open list:PERFORMANCE EVENTS SUBSYSTEM" , "open list:PERFORMANCE EVENTS SUBSYSTEM" , "open list:BPF (Safe dynamic programs and tools)" , "open list:BPF (Safe dynamic programs and tools)" From: =?utf-8?b?546L6LSH?= Subject: [RFC PATCH] perf: fix panic by mark recursion inside perf_log_throttle Message-ID: Date: Thu, 9 Sep 2021 11:13:21 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When running with ftrace function enabled, we observed panic as below: traps: PANIC: double fault, error_code: 0x0 [snip] RIP: 0010:perf_swevent_get_recursion_context+0x0/0x70 [snip] Call Trace: perf_trace_buf_alloc+0x26/0xd0 perf_ftrace_function_call+0x18f/0x2e0 kernelmode_fixup_or_oops+0x5/0x120 __bad_area_nosemaphore+0x1b8/0x280 do_user_addr_fault+0x410/0x920 exc_page_fault+0x92/0x300 asm_exc_page_fault+0x1e/0x30 RIP: 0010:__get_user_nocheck_8+0x6/0x13 perf_callchain_user+0x266/0x2f0 get_perf_callchain+0x194/0x210 perf_callchain+0xa3/0xc0 perf_prepare_sample+0xa5/0xa60 perf_event_output_forward+0x7b/0x1b0 __perf_event_overflow+0x67/0x120 perf_swevent_overflow+0xcb/0x110 perf_swevent_event+0xb0/0xf0 perf_tp_event+0x292/0x410 perf_trace_run_bpf_submit+0x87/0xc0 perf_trace_lock_acquire+0x12b/0x170 lock_acquire+0x1bf/0x2e0 perf_output_begin+0x70/0x4b0 perf_log_throttle+0xe2/0x1a0 perf_event_nmi_handler+0x30/0x50 nmi_handle+0xba/0x2a0 default_do_nmi+0x45/0xf0 exc_nmi+0x155/0x170 end_repeat_nmi+0x16/0x55 According to the trace we know the story is like this, the NMI triggered perf IRQ throttling and call perf_log_throttle(), which triggered the swevent overflow, and the overflow process do perf_callchain_user() which triggered a user PF, and the PF process triggered perf ftrace which finally lead into a suspected stack overflow. This patch marking the context as recursion during perf_log_throttle() , so no more swevent during the process and no more panic. Signed-off-by: Michael Wang Tested-by: Michael Wang --- kernel/events/core.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 744e872..6063443 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8716,6 +8716,7 @@ static void perf_log_throttle(struct perf_event *event, int enable) struct perf_output_handle handle; struct perf_sample_data sample; int ret; + int rctx; struct { struct perf_event_header header; @@ -8738,14 +8739,17 @@ static void perf_log_throttle(struct perf_event *event, int enable) perf_event_header__init_id(&throttle_event.header, &sample, event); + rctx = perf_swevent_get_recursion_context(); ret = perf_output_begin(&handle, &sample, event, throttle_event.header.size); - if (ret) - return; + if (!ret) { + perf_output_put(&handle, throttle_event); + perf_event__output_id_sample(event, &handle, &sample); + perf_output_end(&handle); + } - perf_output_put(&handle, throttle_event); - perf_event__output_id_sample(event, &handle, &sample); - perf_output_end(&handle); + if (rctx >= 0) + perf_swevent_put_recursion_context(rctx); } /*