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

[Joonsoo Kim <iamjoonsoo.kim@lge.com>]

On Mon, Aug 11, 2014 at 02:53:35PM +0530, Aneesh Kumar K.V wrote:
> Joonsoo Kim <iamjoonsoo.kim@lge.com> writes:
> 
> > The check '!PageBuddy(page) && page_count(page) == 0 &&
> > migratetype == MIGRATE_ISOLATE' would mean the page on free processing.
> > 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
> > since it requires that the page is on buddy. I think that removing
> > this unstability is good thing.
> 
> Is that true in case of check_pages_isolated_cb ? Does that require
> PageBuddy to be true ?

I think so.

> 
> >
> > 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.
> 
> Can you quote the patch summary in the above case ? ie, something like
> 
> And the followiing patch "mm/....." makes isolate freepage.
> 

Okay.

"mm/isolation: change pageblock isolation logic to fix freepage
counting bugs" introduce PageIsolated() and mark freepages
PageIsolated() during isolation. Those pages are !PageBuddy() and
page_count() == 0.

Thanks.