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Date:   Thu, 26 Sep 2019 16:58:49 +0800
From:   Peter Xu <peterx@redhat.com>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Linux-MM <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Hugh Dickins <hughd@google.com>,
        Maya Gokhale <gokhale2@llnl.gov>,
        Jerome Glisse <jglisse@redhat.com>,
        Pavel Emelyanov <xemul@virtuozzo.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Martin Cracauer <cracauer@cons.org>,
        Marty McFadden <mcfadden8@llnl.gov>, Shaohua Li <shli@fb.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Denis Plotnikov <dplotnikov@virtuozzo.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Mel Gorman <mgorman@suse.de>,
        "Kirill A . Shutemov" <kirill@shutemov.name>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH v4 05/10] mm: Return faster for non-fatal signals in user
 mode faults
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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