Messages in this thread | | | Date | Mon, 9 Dec 2013 16:00:24 +0000 | From | Christoph Lameter <> | Subject | Re: [PATCH 14/15] mm: fix TLB flush race between migration, and change_protection_range |
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On Fri, 6 Dec 2013, Rik van Riel wrote:
> > Ok then what are you trying to fix? > > It would help if you had actually read the patch.
I read the patch. Please update the documentation to accurately describe the race.
From what I can see this race affects only huge pages and the basic issue seems to be that huge pages do not use migration entries but directly replace the pmd (migrate_misplaced_transhuge_page() f.e.).
That is not safe and there may be multiple other races as we add more general functionality to huge pages. An intermediate stage is needed that allows the clearing out of remote tlb entries before the new tlb entry becomes visible.
Then you wont need this code anymore.
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