Re: [PATCH] ring_buffer: map to cpu not page

From: Ingo Molnar
Date: Fri Oct 03 2008 - 03:30:14 EST



* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> My original patch had a compile bug when NUMA was configured. I
> referenced cpu when it should have been cpu_buffer->cpu.
>
> Ingo quickly fixed this bug by replacing cpu with 'i' because that was
> the loop counter. Unfortunately, the 'i' was the counter of pages, not
> CPUs. This caused a crash when the number of pages allocated for the
> buffers exceeded the number of pages, which would usually be the case.
>
> Signed-off-by: Steven Rostedt <srostedt@xxxxxxxxxx>

> for (i = 0; i < nr_pages; i++) {
> page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()),
> - GFP_KERNEL, cpu_to_node(i));
> + GFP_KERNEL, cpu_to_node(cpu_buffer->cpu));

oh, stupid typo of the year :-)

applied to tip/tracing/ring-buffer, thanks for tracking it down! I've
reactivated the topic branch for tip/master and i'm running a few tests
before pushing it out for wider testing.

Ingo
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