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SubjectRe: [patch] mm: xip fix fault vs sparse page invalidate race
Nick Piggin wrote:
> XIP has a race between sparse pages being inserted into page tables, and
> sparse pages being zapped when its time to put a non-sparse page in.
>
> What can happen is that a process can be left with a dangling sparse page
> in a MAP_SHARED mapping, while the rest of the world sees the non-sparse
> version. Ie. data corruption.
>
> Guard these operations with a seqlock, making fault-in-sparse-pages
> the slowpath, and try-to-unmap-sparse-pages the fastpath.
>
> Signed-off-by: Nick Piggin <npiggin@suse.de>
Ouch.
Acked-by: Carsten Otte <cotte@de.ibm.com>


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