Re: + mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported-v2.patch added to -mm tree

[Mel Gorman <mgorman@techsingularity.net>]

On Fri, May 26, 2017 at 03:52:21PM +0100, Punit Agrawal wrote:
> > I've never looked too closely at how hardware poisoning and hugetlb pages
> > migration is handled so I could easily have missed something but this
> > changelog and patch confuses me.
> >
> > Surely if the inconsistency is between hugepage_migration_supported and
> > !hugepage_migration_supported then the check in soft_offline_huge_page()
> > should also be related to hugepage_migration_supported either in
> > soft_offline_huge_page() or in putback_movable_pages()?
> 
> The first version of the patch did indeed make a change that was around
> !hugepage_migration_supported() [0] which was effectively a revert of
> 32665f2bbfed ("mm/migrate: correct failure handling if
> !hugepage_migration_support()").
> 
> But Horiguchi-san suggested that dropping the putback_active_hugepage()
> from unmap_and_move_hugepage() will bring back the issue that
> 32665f2bbfed addressed it was safer to take the current approach. It
> also matches the pattern followed for !hugepage.
> 
> I did update the changelog but perhaps not enough - would updating the
> changelog to reflect this help make it clearer?
> 

Ok, I see what the patch is doing now. I don't think you need to alter
the changelog as I think the patch is ok.

Thanks for clarifying.

-- 
Mel Gorman
SUSE Labs