linux-kernel - Re: [PATCH AUTOSEL 6.17-6.1] ftrace: Fix softlockup in ftrace_module

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Message-ID: <aQECCjH3rMiUSj-f@laps>
Date: Tue, 28 Oct 2025 13:48:58 -0400
From: Sasha Levin <sashal@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: patches@...ts.linux.dev, stable@...r.kernel.org,
	Vladimir Riabchun <ferr.lambarginio@...il.com>, mhiramat@...nel.org,
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 6.17-6.1] ftrace: Fix softlockup in
 ftrace_module_enable

On Sat, Oct 25, 2025 at 03:25:45PM -0400, Steven Rostedt wrote:
>On Sat, 25 Oct 2025 12:00:16 -0400
>Sasha Levin <sashal@...nel.org> wrote:
>
>> - The change inserts `cond_resched()` inside the inner iteration over
>>   every ftrace record (`kernel/trace/ftrace.c:7538`). That loop holds
>>   the ftrace mutex and, for each record, invokes heavy helpers like
>>   `test_for_valid_rec()` which in turn calls `kallsyms_lookup()`
>>   (`kernel/trace/ftrace.c:4289`). On huge modules (e.g. amdgpu) this can
>>   run for tens of milliseconds with preemption disabled, triggering the
>
>It got the "preemption disabled" wrong. Well maybe when running
>PREEMPT_NONE it is, but the description doesn't imply that.

Thanks for the review! I've been trying a new LLM for part of this series, and
it seems to underperform the one I was previously using.

-- 
Thanks,
Sasha