Re: [PATCH 0/7] remove SLOB and allow kfree() with kmem_cache_alloc()

Vlastimil Babka
2023-03-15T13:53:20Z

On 3/13/23 17:31, Steven Rostedt wrote:
> Just remove that comment. And you could even add:
>
> Suggested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> Fixes: e4c2ce82ca27 ("ring_buffer: allocate buffer page pointer")

Thanks for the analysis. Want to take the following patch to your tree or
should I make it part of the series?

----8<----
From 297a8c8fda98dc5499cfe0eac6ffabfb19d1b70f Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <vbabka@suse.cz>
Date: Wed, 15 Mar 2023 14:45:15 +0100
Subject: [PATCH] ring-buffer: remove obsolete comment for free_buffer_page()

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@gmail.com>
Suggested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Fixes: e4c2ce82ca27 ("ring_buffer: allocate buffer page pointer")
Signed-off-by: Vlastimil Babka <vbabka@suse.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.
- */
static void free_buffer_page(struct buffer_page *bpage)
{
free_page((unsigned long)bpage->page);
--
2.39.2