linux-kernel - Re: [PATCH] ring-buffer: remove obsolete comment for free_buffer

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Message-ID: <72de48c7-014d-80ac-51e9-ba22450f1d5b@quicinc.com>
Date:   Wed, 15 Mar 2023 21:21:15 +0530
From:   Mukesh Ojha <quic_mojha@...cinc.com>
To:     Vlastimil Babka <vbabka@...e.cz>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Ingo Molnar <mingo@...e.hu>
CC:     <linux-trace-kernel@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <patches@...ts.linux.dev>,
        Mike Rapoport <mike.rapoport@...il.com>
Subject: Re: [PATCH] ring-buffer: remove obsolete comment for
 free_buffer_page()



On 3/15/2023 7:54 PM, Vlastimil Babka wrote:
> The comment refers to mm/slob.o which is being removed. It comes from


> commit ed56829cb319 ("ring_buffer: reset buffer page when freeing") and
> according to Steven the borrowed code was a page mapcount and mapping
> reset, which was later removed by commit e4c2ce82ca27 ("ring_buffer:
> allocate buffer page pointer"). Thus the comment is not accurate anyway,
> remove it.
> 
> Reported-by: Mike Rapoport <mike.rapoport@...il.com>
> Suggested-by: Steven Rostedt (Google) <rostedt@...dmis.org>
> Fixes: e4c2ce82ca27 ("ring_buffer: allocate buffer page pointer")
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> ---
>   kernel/trace/ring_buffer.c | 4 ----
>   1 file changed, 4 deletions(-)
> 
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index af50d931b020..c6f47b6cfd5f 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -354,10 +354,6 @@ static void rb_init_page(struct buffer_data_page *bpage)
>   	local_set(&bpage->commit, 0);
>   }
>   
> -/*
> - * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing
> - * this issue out.
> - */

Thanks for the clean up.

Reviewed-by: Mukesh Ojha <quic_mojha@...cinc.com>

-- Mukesh

>   static void free_buffer_page(struct buffer_page *bpage)
>   {
>   	free_page((unsigned long)bpage->page);