Re: [PATCH v4 05/10] mm: Return faster for non-fatal signals in user mode faults

From: Peter Xu
Date: Thu Sep 26 2019 - 04:59:06 EST


On Tue, Sep 24, 2019 at 08:45:18AM -0700, Matthew Wilcox wrote:

[...]

> Oh, and while you're looking at the callers of handle_mm_fault(), a
> lot of them don't check conditions in the right order. x86, at least,
> handles FAULT_RETRY before handling FAULT_ERROR, which is clearly wrong.
>
> Kirill and I recently discussed it here:
> https://lore.kernel.org/linux-mm/20190911152338.gqqgxrmqycodfocb@box/T/

Is there any existing path in master that we can get VM_FAULT_RETRY
returned with any existing VM_FAULT_ERROR bit? It seems to me that
above link is the first one that is going to introduce such case?

If so, I'm uncertain now on whether I should have one patch to handle
the ERROR case first as you suggested with this series, because
otherwise that patch won't explain itself without a real benefit...

Thanks,

--
Peter Xu