Re: [PATCH 2/4] mm: migrate: Close race between migration completion and mprotect

[Rik van Riel]

On 10/02/2014 09:29 AM, Mel Gorman wrote:
> A migration entry is marked as write if pte_write was true at the time the
> entry was created. The VMA protections are not double checked when migration
> entries are being removed as mprotect marks write-migration-entries as
> read. It means that potentially we take a spurious fault to mark PTEs write
> again but it's straight-forward. However, there is a race between write
> migrations being marked read and migrations finishing. This potentially
> allows a PTE to be write that should have been read. Close this race by
> double checking the VMA permissions when migration completes.
> 
> Signed-off-by: Mel Gorman <mgorman@xxxxxxx>

Acked-by: Rik van Riel <riel@xxxxxxxxxx>

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