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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
Date: Thu, 26 Sep 2019 16:58:49 +0800	[thread overview]
Message-ID: <20190926085849.GA3077@xz-x1> (raw)
In-Reply-To: <20190924154518.GG1855@bombadil.infradead.org>

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


  parent reply	other threads:[~2019-09-26  8:59 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-23  4:25 [PATCH v4 00/10] mm: Page fault enhancements Peter Xu
2019-09-23  4:25 ` [PATCH v4 01/10] mm/gup: Rename "nonblocking" to "locked" where proper Peter Xu
2019-09-23  4:25 ` [PATCH v4 02/10] mm/gup: Fix __get_user_pages() on fault retry of hugetlb Peter Xu
2019-09-23  4:25 ` [PATCH v4 03/10] mm: Introduce FAULT_FLAG_DEFAULT Peter Xu
2019-09-23  4:25 ` [PATCH v4 04/10] mm: Introduce FAULT_FLAG_INTERRUPTIBLE Peter Xu
2019-09-23  4:25 ` [PATCH v4 05/10] mm: Return faster for non-fatal signals in user mode faults Peter Xu
2019-09-23 18:03   ` Linus Torvalds
2019-09-24  2:47     ` Peter Xu
2019-09-24  2:54       ` Matthew Wilcox
2019-09-24  3:19         ` Peter Xu
2019-09-24 15:45           ` Matthew Wilcox
2019-09-25  3:46             ` Peter Xu
2019-09-26  8:58             ` Peter Xu [this message]
2019-10-08 22:43   ` Palmer Dabbelt
2019-10-09  7:41     ` Peter Xu
2019-09-23  4:25 ` [PATCH v4 06/10] userfaultfd: Don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-09-23  4:25 ` [PATCH v4 07/10] mm: Allow VM_FAULT_RETRY for multiple times Peter Xu
2019-09-23  4:25 ` [PATCH v4 08/10] mm/gup: " Peter Xu
2019-09-23  4:25 ` [PATCH v4 09/10] mm/gup: Allow to react to fatal signals Peter Xu
2019-09-23  4:25 ` [PATCH v4 10/10] mm/userfaultfd: Honor FAULT_FLAG_KILLABLE in fault path Peter Xu

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