Re: [Xen-devel] [PATCH v4 1/8] mm: Place unscrubbed pages at the end of pagelist

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.06.17 at 22:07, <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 06/09/2017 10:50 AM, Jan Beulich wrote:
>>>>> On 19.05.17 at 17:50, <boris.ostrovsky@xxxxxxxxxx> wrote:
>>> +            unsigned int first_dirty;
>> On x86 this change is fine at present, albeit not optimal. Its ARM
>> equivalent, however, grows struct page_info in the 32-bit case,
> 
> It does? I am looking at include/asm-arm/mm.h and I don't see this.

The union with field name u is 32 bits on 32-bit ARM right now.
You change grows it to 64 bits.

>> which I don't think is wanted or needed. You really only need
>> MAX_ORDER+1 bits here, so I'd suggest making this a bit field
> 
> Just to make sure --- when you say "bit field" you mean masking various
> bits in a word, not C language bit fields?

No, actually the latter.

Jan


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