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

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Message-Id: <20250911223813.58c894b4c8ce8e3eba298c71@kernel.org>
Date: Thu, 11 Sep 2025 22:38:13 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Vladimir Riabchun <ferr.lambarginio@...il.com>
Cc: rostedt@...dmis.org, mhiramat@...nel.org, mark.rutland@....com,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH] ftrace: Fix softlockup in ftrace_module_enable

On Thu, 11 Sep 2025 15:33:15 +0200
Vladimir Riabchun <ferr.lambarginio@...il.com> wrote:

> A soft lockup was observed when loading amdgpu module,
> this is the same issue that was fixed in
> commit d0b24b4e91fc ("ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY
> kernels") and commit 42ea22e754ba ("ftrace: Add cond_resched() to
> ftrace_graph_set_hash()").
> 
> Fix it the same way by adding cond_resched() in ftrace_module_enable.
> 

Looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thanks,

> Signed-off-by: Vladimir Riabchun <ferr.lambarginio@...il.com>
> ---
>  kernel/trace/ftrace.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index a69067367c29..23c4d37c7bcd 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -7526,6 +7526,9 @@ void ftrace_module_enable(struct module *mod)
>  
>  	do_for_each_ftrace_rec(pg, rec) {
>  		int cnt;
> +
> +		cond_resched();
> +
>  		/*
>  		 * do_for_each_ftrace_rec() is a double loop.
>  		 * module text shares the pg. If a record is
> -- 
> 2.43.0
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>