From mboxrd@z Thu Jan 1 00:00:00 1970 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 B01D5C433F5 for ; Tue, 26 Oct 2021 02:11:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AC476103C for ; Tue, 26 Oct 2021 02:11:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233064AbhJZCNi (ORCPT ); Mon, 25 Oct 2021 22:13:38 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:42134 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230216AbhJZCNe (ORCPT ); Mon, 25 Oct 2021 22:13:34 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R201e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=yun.wang@linux.alibaba.com;NM=1;PH=DS;RN=31;SR=0;TI=SMTPD_---0UtjMs7q_1635214264; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UtjMs7q_1635214264) by smtp.aliyun-inc.com(127.0.0.1); Tue, 26 Oct 2021 10:11:06 +0800 Subject: Re: [PATCH v4 0/2] fix & prevent the missing preemption disabling From: =?UTF-8?B?546L6LSH?= To: Guo Ren , Steven Rostedt , Ingo Molnar , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Colin Ian King , Masami Hiramatsu , "Peter Zijlstra (Intel)" , Nicholas Piggin , Jisheng Zhang , linux-csky@vger.kernel.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, live-patching@vger.kernel.org References: <32a36348-69ee-6464-390c-3a8d6e9d2b53@linux.alibaba.com> Message-ID: <71c21f78-9c44-fdb2-f8e2-d8544b3421bd@linux.alibaba.com> Date: Tue, 26 Oct 2021 10:09:12 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <32a36348-69ee-6464-390c-3a8d6e9d2b53@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Just a ping, to see if there are any more comments :-P Regards, Michael Wang On 2021/10/18 上午11:38, ηŽ‹θ΄‡ wrote: > The testing show that perf_ftrace_function_call() are using smp_processor_id() > with preemption enabled, all the checking on CPU could be wrong after preemption. > > As Peter point out, the section between ftrace_test_recursion_trylock/unlock() > pair require the preemption to be disabled as 'Documentation/trace/ftrace-uses.rst' > explained, but currently the work is done outside of the helpers. > > And since the internal using of trace_test_and_set_recursion() > and trace_clear_recursion() also require preemption to be disabled, we > can just merge the logical together. > > Patch 1/2 will make sure preemption disabled when recursion lock succeed, > patch 2/2 will do smp_processor_id() checking after trylock() to address the > issue. > > v1: https://lore.kernel.org/all/8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com/ > v2: https://lore.kernel.org/all/b1d7fe43-ce84-0ed7-32f7-ea1d12d0b716@linux.alibaba.com/ > v3: https://lore.kernel.org/all/609b565a-ed6e-a1da-f025-166691b5d994@linux.alibaba.com/ > > Michael Wang (2): > ftrace: disable preemption when recursion locked > ftrace: do CPU checking after preemption disabled > > arch/csky/kernel/probes/ftrace.c | 2 -- > arch/parisc/kernel/ftrace.c | 2 -- > arch/powerpc/kernel/kprobes-ftrace.c | 2 -- > arch/riscv/kernel/probes/ftrace.c | 2 -- > arch/x86/kernel/kprobes/ftrace.c | 2 -- > include/linux/trace_recursion.h | 20 +++++++++++++++++++- > kernel/livepatch/patch.c | 13 +++++++------ > kernel/trace/ftrace.c | 15 +++++---------- > kernel/trace/trace_event_perf.c | 6 +++--- > kernel/trace/trace_functions.c | 5 ----- > 10 files changed, 34 insertions(+), 35 deletions(-) >