Messages in this thread | | | From | Naoya Horiguchi <> | Subject | Re: [PATCH v2 04/12] mm: thp: introduce CONFIG_ARCH_ENABLE_THP_MIGRATION | Date | Tue, 29 Nov 2016 07:50:06 +0000 |
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On Mon, Nov 28, 2016 at 03:21:54PM +0100, Michal Hocko wrote: > On Tue 08-11-16 08:31:49, Naoya Horiguchi wrote: > > Introduces CONFIG_ARCH_ENABLE_THP_MIGRATION to limit thp migration > > functionality to x86_64, which should be safer at the first step. > > Please make sure to describe why this has to be arch specific and what > are arches supposed to provide in order to enable this option.
OK, the below will be added in the future version:
Thp migration is an arch-specific feature because it depends on the arch-dependent behavior of non-present format of page table entry. What you need to enable this option in other archs are: - to define arch-specific transformation functions like __pmd_to_swp_entry() and __swp_entry_to_pmd(), - to make sure that arch-specific page table walking code can properly handle !pmd_present case (gup_pmd_range() is a good example), - (if your archs enables CONFIG_HAVE_ARCH_SOFT_DIRTY,) to define soft dirty routines like pmd_swp_mksoft_dirty.
Thanks, Naoya Horiguchi
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