Hi, Suren,
On Fri, Apr 14, 2023 at 03:14:23PM -0700, Suren Baghdasaryan wrote:
> > It also already ignores invalid faults:
> >
> > if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY))
> > return;
>
> Can there be a case of (!VM_FAULT_ERROR && VM_FAULT_RETRY) - basically
> we need to retry but no errors happened? If so then this condition
> would double-count pagefaults in such cases.
If ret==VM_FAULT_RETRY it should return here already, so I assume
mm_account_fault() itself is fine regarding fault retries?
Note that I think "ret & (VM_FAULT_ERROR | VM_FAULT_RETRY)" above means
"either ERROR or RETRY we'll skip the accounting".
IMHO we should have 3 cases here:
- ERROR && !RETRY
error triggered of any kind
- RETRY && !ERROR
we need to try one more time
- !RETRY && !ERROR
we finished the fault
I don't think ERROR & RETRY can even be set at the same time so I assume
there's no option 4) - a RETRY should imply no ERROR already, even though
it's still incomplete so need another attempt.
Thanks,
--
Peter Xu
