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    Subject[PATCH 1/3] futex: do not pagefault_disable in futex_atomic_cmpxchg_inatomic()
    kernel/futex.c disables page faults before calling
    futex_atomic_cmpxchg_inatomic(), so there is no need to do it again
    within that function.

    Signed-off-by: Michel Lespinasse <walken@google.com>

    diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h
    index b33fe70..7133a86 100644
    --- a/arch/arm/include/asm/futex.h
    +++ b/arch/arm/include/asm/futex.h
    @@ -95,7 +95,8 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
    if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
    return -EFAULT;

    - pagefault_disable(); /* implies preempt_disable() */
    + /* Note that preemption is disabled by futex_atomic_cmpxchg_inatomic
    + * call sites. */

    __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
    "1: " T(ldr) " %0, [%3]\n"
    @@ -115,8 +116,6 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
    : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
    : "cc", "memory");

    - pagefault_enable(); /* subsumes preempt_enable() */
    -
    return val;
    }

    --
    Michel "Walken" Lespinasse
    A program is never fully debugged until the last user dies.

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