Re: [PATCH v2 2/8] mm/isolation: remove unstable check for isolated page

[Joonsoo Kim]

On Thu, Aug 07, 2014 at 03:49:17PM +0200, Vlastimil Babka wrote:
> On 08/06/2014 09:18 AM, Joonsoo Kim wrote:
> >The check '!PageBuddy(page) && page_count(page) == 0 &&
> >migratetype == MIGRATE_ISOLATE' would mean the page on free processing.
> 
> What is "the page on free processing"? I thought this test means the
> page is on some CPU's pcplist?

Yes, you are right.

> 
> >Although it could go into buddy allocator within a short time,
> >futher operation such as isolate_freepages_range() in CMA, called after
> >test_page_isolated_in_pageblock(), could be failed due to this unstability
> 
> By "unstability" you mean the page can be allocated again from the
> pcplist instead of being freed to buddy list?

Yes.

> >since it requires that the page is on buddy. I think that removing
> >this unstability is good thing.
> >
> >And, following patch makes isolated freepage has new status matched with
> >this condition and this check is the obstacle to that change. So remove
> >it.
> 
> You could also say that pages from isolated pageblocks can no longer
> appear on pcplists after the later patches.

Okay. I will do it.

Thanks.
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