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    Subject[PATCH 3.16.y-ckt 068/135] um: Skip futex_atomic_cmpxchg_inatomic() test
    Date
    3.16.7-ckt6 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Richard Weinberger <richard@nod.at>

    commit f911d731054ab3d82ee72a16b889e17ca3a2332a upstream.

    futex_atomic_cmpxchg_inatomic() does not work on UML because
    it triggers a copy_from_user() in kernel context.
    On UML copy_from_user() can only be used if the kernel was called
    by a real user space process such that UML can use ptrace()
    to fetch the value.

    Reported-by: Miklos Szeredi <miklos@szeredi.hu>
    Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
    Signed-off-by: Richard Weinberger <richard@nod.at>
    Tested-by: Daniel Walter <d.walter@0x90.at>
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    ---
    arch/um/Kconfig.common | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common
    index 6915d28cf118..85a70c14d70f 100644
    --- a/arch/um/Kconfig.common
    +++ b/arch/um/Kconfig.common
    @@ -3,6 +3,7 @@ config UML
    default y
    select HAVE_ARCH_AUDITSYSCALL
    select HAVE_UID16
    + select HAVE_FUTEX_CMPXCHG if FUTEX
    select GENERIC_IRQ_SHOW
    select GENERIC_CPU_DEVICES
    select GENERIC_IO
    --
    2.1.4


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