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    SubjectRe: [PATCH] mm: pass mm to grab_swap_token
    On Sun, 21 Jun 2009 14:02:43 +0100 (BST)
    Hugh Dickins <hugh.dickins@tiscali.co.uk> wrote:

    > If a kthread happens to use get_user_pages() on an mm (as KSM does),
    > there's a chance that it will end up trying to read in a swap page,
    > then oops in grab_swap_token() because the kthread has no mm: GUP
    > passes down the right mm, so grab_swap_token() ought to be using it.
    >
    > We have not identified a stronger case than KSM's daemon (not yet
    > in mainline), but the issue must have come up before, since RHEL has
    > included a fix for this for years (though a different fix, they just
    > back out of grab_swap_token if current->mm is unset: which is what
    > we first proposed, but using the right mm here seems more correct).
    >
    > Reported-by: Izik Eidus <ieidus@redhat.com>
    > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
    > Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
    > Acked-by: Rik van Riel <riel@redhat.com>
    Reviewed-by: Minchan Kim <minchan.kim@gmail.com>

    I already added my sign to Hannes but it is folded in this patch.

    --
    Kinds Regards
    Minchan Kim


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