Re: [patch] mm: xip fix fault vs sparse page invalidate race

[Carsten Otte]

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@xxxxxxx>
Ouch.
Acked-by: Carsten Otte <cotte@xxxxxxxxxx>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/