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SubjectRe: [PATCH] perf/core: don't WARN for impossible rb sizes
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On 2/12/2019 9:07 PM, Peter Zijlstra wrote:
> On Tue, Feb 12, 2019 at 10:42:38AM +0800, Jin, Yao wrote:
>>> diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
>>> index 4a9937076331..309ef5a64af5 100644
>>> --- a/kernel/events/ring_buffer.c
>>> +++ b/kernel/events/ring_buffer.c
>>> @@ -734,6 +734,9 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
>>> size = sizeof(struct ring_buffer);
>>> size += nr_pages * sizeof(void *);
>>> + if (order_base_2(size) >= MAX_ORDER)
>>> + goto fail;
>>> +
>>> rb = kzalloc(size, GFP_KERNEL);
>
> Yes, Boris also send the entire morning bisecting this.
>
> The problem is that @size is in bytes and MAX_ORDER is in pages.
>
> That should be:
>
> if (order_base_2(size) >= PAGE_SHIFT+MAX_ORDER)
>
>

Thanks Peter! This fix works!

Thanks
Jin Yao

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