On Sun, 10 Dec 2023 22:12:50 -0500
Steven Rostedt <rost...@goodmis.org> wrote:
> From: "Steven Rostedt (Google)" <rost...@goodmis.org>
>
> Reading the ring buffer does a swap of a sub-buffer within the ring buffer
> with a empty sub-buffer. This allows the reader to have full access to the
> content of the sub-buffer that was swapped out without having to worry
> about contention with the writer.
>
> The readers call ring_buffer_alloc_read_page() to allocate a page that
> will be used to swap with the ring buffer. When the code is finished with
> the reader page, it calls ring_buffer_free_read_page(). Instead of freeing
> the page, it stores it as a spare. Then next call to
> ring_buffer_alloc_read_page() will return this spare instead of calling
> into the memory management system to allocate a new page.
>
> Unfortunately, on freeing of the ring buffer, this spare page is not
> freed, and causes a memory leak.
>
Oops, Looks good to me.
Acked-by: Masami Hiramatsu (Google) <mhira...@kernel.org>
Thanks,
> Cc: sta...@vger.kernel.org
> Fixes: 73a757e63114d ("ring-buffer: Return reader page back into existing
> ring buffer")
> Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
> ---
> kernel/trace/ring_buffer.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index a38e5a3c6803..dd37d21d6e55 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -1790,6 +1790,8 @@ static void rb_free_cpu_buffer(struct
> ring_buffer_per_cpu *cpu_buffer)
> free_buffer_page(bpage);
> }
>
> + free_page((unsigned long)cpu_buffer->free_page);
> +
> kfree(cpu_buffer);
> }
>
> --
> 2.42.0
>
--
Masami Hiramatsu (Google) <mhira...@kernel.org>
