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    SubjectRe: [PATCH 5/5] x86,mm: make pagefault killable
    On 03/22, KOSAKI Motohiro wrote:
    >
    > This patch makes pagefault interruptible by SIGKILL.

    Not a comment, but the question...

    > --- a/arch/x86/mm/fault.c
    > +++ b/arch/x86/mm/fault.c
    > @@ -1035,6 +1035,7 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code)
    > if (user_mode_vm(regs)) {
    > local_irq_enable();
    > error_code |= PF_USER;
    > + flags |= FAULT_FLAG_KILLABLE;

    OK, this is clear.

    I am wondering, can't we set FAULT_FLAG_KILLABLE unconditionally
    but check PF_USER when we get VM_FAULT_RETRY? I mean,

    if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
    if (!(error_code & PF_USER))
    no_context(...);
    return;
    }


    Probably not... but I can't find any example of in-kernel fault which
    can be broken by -EFAULT if current was killed.

    mm_release()->put_user(clear_child_tid) should be fine...

    Just curious, I feel I missed something obvious.

    Oleg.



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