Re: [PATCH v4 08/13] x86, kasan: clarify kasan's dependency on vmemmap_populate_hugepages()

[Andrey Ryabinin]

On 03/16/2017 09:07 AM, Dan Williams wrote:
> Historically kasan has not been careful about whether vmemmap_populate()
> internally allocates a section worth of memmap even if the parameters
> call for less.  For example, a request to shadow map a single page
> results in a full section (128MB) that contains that page being mapped.
> Also, kasan has not been careful to handle cases where this section
> promotion causes overlaps / overrides of previous calls to
> vmemmap_populate().
> 
> Before we teach vmemmap_populate() to support sub-section hotplug,
> arrange for kasan to explicitly avoid vmemmap_populate_basepages().
> This should be functionally equivalent to the current state since
> CONFIG_KASAN requires x86_64 (implies PSE) and it does not collide with
> sub-section hotplug support since CONFIG_KASAN disables
> CONFIG_MEMORY_HOTPLUG.
> 
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Cc: Alexander Potapenko <glider@xxxxxxxxxx>
> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
> Reported-by: Nicolai Stange <nicstange@xxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>

Acked-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>