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    SubjectRe: [GIT pull] futex fixes for 2.6.31
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    On Wed, 2009-06-24 at 21:48 +0200, Thomas Gleixner wrote:
    > Linus,
    >
    > Please pull the latest futexes-for-linus git tree from:
    >
    > git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git futexes-for-linus
    >
    > Thanks,
    >
    > tglx
    >
    > ------------------>
    > Thomas Gleixner (1):
    > futex: Fix the write access fault problem for real
    >
    >
    > kernel/futex.c | 45 ++++++++++++++++++++++++---------------------
    > 1 files changed, 24 insertions(+), 21 deletions(-)
    >
    > diff --git a/kernel/futex.c b/kernel/futex.c
    > index 80b5ce7..1c33711 100644
    > --- a/kernel/futex.c
    > +++ b/kernel/futex.c
    > @@ -284,6 +284,25 @@ void put_futex_key(int fshared, union futex_key *key)
    > drop_futex_key_refs(key);
    > }
    >
    > +/*
    > + * fault_in_user_writeable - fault in user address and verify RW access
    > + * @uaddr: pointer to faulting user space address
    > + *
    > + * Slow path to fixup the fault we just took in the atomic write
    > + * access to @uaddr.
    > + *
    > + * We have no generic implementation of a non destructive write to the
    > + * user address. We know that we faulted in the atomic pagefault
    > + * disabled section so we can as well avoid the #PF overhead by
    > + * calling get_user_pages() right away.
    > + */
    > +static int fault_in_user_writeable(u32 __user *uaddr)
    > +{
    > + int ret = get_user_pages(current, current->mm, (unsigned long)uaddr,
    > + sizeof(*uaddr), 1, 0, NULL, NULL);
    The 4th parameter of get_user_pages means page number. sizeof(*uaddr) is equal to
    4, so you want 4 pages?

    Yanmin


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