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Date: Wed, 09 Oct 2013 23:26:58 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [patch 1/2] qemu: mempath: prefault pages manually
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To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: qemu-devel@nongnu.org

Il 09/10/2013 21:41, Marcelo Tosatti ha scritto:
>> > How was that tested?  For BUS_MCEERR_AO it can work, but BUS_MCEERR_AR
>> > calls force_sig_info which does this:
>> > 
>> >         ignored = action->sa.sa_handler == SIG_IGN;
>> >         blocked = sigismember(&t->blocked, sig);
>> >         if (blocked || ignored) {
>> >                 action->sa.sa_handler = SIG_DFL;
>> >                 if (blocked) {
>> >                         sigdelset(&t->blocked, sig);
>> >                         recalc_sigpending_and_wake(t);
>> >                 }
>> >         
>> >         if (action->sa.sa_handler == SIG_DFL)
>> >                 t->signal->flags &= ~SIGNAL_UNKILLABLE;
>> > 
>> > and kills the process (because that's the default action of SIG_DFL).
> For vcpu context its not blocked?

It causes KVM to exit back to userspace, but as soon as KVM exits it
should be blocked.  Thus a SIGBUS with BUS_MCEERR_AR will never be
returned by sigtimedwait.

Paolo