linux-kernel - Re: [PATCH v2 0/2] fix & prevent the missing preemption disabling

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Message-ID: <69e9cf98-883c-0016-4b07-12afbf138094@linux.alibaba.com>
Date:   Wed, 13 Oct 2021 11:33:27 +0800
From:   王贇 <yun.wang@...ux.alibaba.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Guo Ren <guoren@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Helge Deller <deller@....de>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Colin Ian King <colin.king@...onical.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Jisheng Zhang <jszhang@...nel.org>, linux-csky@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-parisc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
        live-patching@...r.kernel.org
Subject: Re: [PATCH v2 0/2] fix & prevent the missing preemption disabling



On 2021/10/13 上午11:26, Steven Rostedt wrote:
> Please start a new thread when sending new versions. v2 should not be a
> reply to v1. If you want to reference v1, just add it to the cover
> letter with a link tag:
> 
> Link: https://lore.kernel.org/all/8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com/

Ok, I'll resend it with link then.

Regards,
Michael Wang


> 
> -- Steve
> 
> 
> On Wed, 13 Oct 2021 11:16:56 +0800
> 王贇 <yun.wang@...ux.alibaba.com> 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.
>>
>> Patch 1/2 will make sure preemption disabled after trylock() succeed,
>> patch 2/2 will do smp_processor_id() checking after trylock to address the
>> issue.
>>
>> Michael Wang (2):
>>   ftrace: disable preemption between ftrace_test_recursion_trylock/unlock()
>>   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      | 22 +++++++++++++++++++++-
>>  kernel/livepatch/patch.c             |  6 ------
>>  kernel/trace/trace_event_perf.c      |  6 +++---
>>  kernel/trace/trace_functions.c       |  5 -----
>>  9 files changed, 24 insertions(+), 25 deletions(-)
>>