Il 28/04/2014 16:06, Andrea Arcangeli ha scritto:
>
> "task" is only used to increment task_struct->xxx_flt. I don't think
> async_pf_execute() actually needs this (current is PF_WQ_WORKER after
> all), but I didn't dare to do another change in the code I can hardly
> understand.
Considering the faults would be randomly distributed among the kworker
threads my preference would also be for NULL instead of current.
ptrace and uprobes tends to be the only two places that look into
other mm with gup, ptrace knows the exact pid that it is triggering
the fault into, so it also can specify the correct task so the fault
goes in the right task struct. uprobes uses NULL.
KVM knows the correct task (it was in current when kvm_create_vm was
called), and doing accounting right would be nice. But I agree that
NULL is less misleading than a dummy current, and I applied patch 3 too.
Paolo
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