Re: [patch 01/10] mm: bootmem: fix checking the bitmap whenfinally freeing bootmem

[Tejun Heo]

On Mon, May 07, 2012 at 01:37:43PM +0200, Johannes Weiner wrote:
> From: Gavin Shan <shangw@xxxxxxxxxxxxxxxxxx>
> 
> When bootmem releases an unaligned chunk of memory at the beginning of
> a node to the page allocator, it iterates from that unaligned PFN but
> checks an aligned word of the page bitmap.  The checked bits do not
> correspond to the PFNs and, as a result, reserved pages can be freed.
> 
> Properly shift the bitmap word so that the lowest bit corresponds to
> the starting PFN before entering the freeing loop.
> 
> This bug has been around since 41546c1 "bootmem: clean up
> free_all_bootmem_core" (2.6.27) without known reports.
> 
> Signed-off-by: Gavin Shan <shangw@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Acked-by: Tejun Heo <tj@xxxxxxxxxx>

Thanks.

-- 
tejun
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