Re: [PATCH] x86/mm/init: respect memblock reserved regions when destroying mappings

["H. Peter Anvin" <hpa@zytor.com>]

On 01/31/2011 07:18 AM, Stefano Stabellini wrote:
> x86/mm/init: respect memblock reserved regions when destroying mappings
> 
> In init_memory_mapping we are destroying all the mappings between
> _brk_end and _end, no matter if some memory areas in that range have
> been reserved using memblock_x86_reserve_range.
> Besides if _end is not pmd aligned we might destroy the
> mappings for valid memory between _end and the following pmd.
> 
> In order to avoid this problem, before clearing any pmds we check if the
> corresponding memory area has been reserved and we only destroy the
> mapping if it hasn't.
> 
> We found this problem because under Xen we have a valid mapping at _end,
> and if _end is not pmd aligned the current code destroys the initial
> part of it.
> 
> In practice this fix does not have any impact on native.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

How on Earth would you end up with a reserved region *inside the BRK*?

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.