Messages in this thread | | | From | Yang Shi <> | Date | Tue, 8 Jun 2021 12:36:05 -0700 | Subject | Re: [PATCH] mm: mempolicy: don't have to split pmd for huge zero page |
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On Tue, Jun 8, 2021 at 10:49 AM Michal Hocko <mhocko@suse.com> wrote: > > On Tue 08-06-21 10:15:36, Yang Shi wrote: > [...] > > I did some archeology, the findings are: > > > > The zero page has PageReserved flag set, it was skipped by the > > explicit PageReserved check in mempolicy.c since commit f4598c8b3678 > > ("[PATCH] migration: make sure there is no attempt to migrate reserved > > pages."). The zero page was not used anymore by do_anonymous_page() > > since 2.6.24 by commit 557ed1fa2620 ("remove ZERO_PAGE"), then > > reinstated by commit a13ea5b759645 ("mm: reinstate ZERO_PAGE") and > > this commit added zero page check in vm_normal_page(), so mempolicy > > doesn't depend on PageReserved check to skip zero page anymore since > > then. > > > > So the zero page is skipped by mempolicy.c since 2.6.16. > > Thanks a lot! This is really useful. Can you just add it to the > changelog so others do not have to go through the painful archeology. > > With that, feel free to add > Acked-by: Michal Hocko <mhocko@suse.com>
Thanks. Will add that into v2.
> > Thanls! > -- > Michal Hocko > SUSE Labs
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