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From: Michal Hocko <mhocko@suse.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux-MM <linux-mm@kvack.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Yu Zhao <yuzhao@google.com>, Andy Lutomirski <luto@kernel.org>,
	Peter Xu <peterx@redhat.com>, Pavel Emelyanov <xemul@openvz.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Minchan Kim <minchan@kernel.org>, Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Hugh Dickins <hughd@google.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Matthew Wilcox <willy@infradead.org>,
	Oleg Nesterov <oleg@redhat.com>, Jann Horn <jannh@google.com>,
	Kees Cook <keescook@chromium.org>,
	Leon Romanovsky <leonro@nvidia.com>, Jan Kara <jack@suse.cz>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	Nadav Amit <nadav.amit@gmail.com>, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 0/1] mm: restore full accuracy in COW page reuse
Date: Mon, 11 Jan 2021 17:15:47 +0100	[thread overview]
Message-ID: <20210111161547.GD22493@dhcp22.suse.cz> (raw)
In-Reply-To: <20210111160549.GN504133@ziepe.ca>

On Mon 11-01-21 12:05:49, Jason Gunthorpe wrote:
> On Sun, Jan 10, 2021 at 11:26:57PM -0800, John Hubbard wrote:
> 
> > So:
> > 
> > FOLL_PIN: would use DMA_PIN_COUNTING_BIAS to increment page refcount.
> > These are long term pins for dma.
> > 
> > FOLL_GET: would use GUP_PIN_COUNTING_BIAS to increment page refcount.
> > These are not long term pins.
> 
> Do we have any places yet that care about the long-term-ness?

I was hoping to use that information to distinguish ephemeral migration
failures due to page reference from long term pins. The later would be a
hard failure for the migration.

-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2021-01-11 16:16 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-10  0:44 [PATCH 0/1] mm: restore full accuracy in COW page reuse Andrea Arcangeli
2021-01-10  0:44 ` [PATCH 1/1] " Andrea Arcangeli
2021-01-10  2:54   ` Andrea Arcangeli
2021-01-11 14:11     ` Kirill A. Shutemov
2021-01-10  0:55 ` [PATCH 0/1] " Linus Torvalds
2021-01-10  0:55   ` Linus Torvalds
2021-01-10  1:19   ` Linus Torvalds
2021-01-10  1:19     ` Linus Torvalds
2021-01-10  1:37     ` Linus Torvalds
2021-01-10  1:37       ` Linus Torvalds
2021-01-10  3:24       ` Andrea Arcangeli
2021-01-10  2:51     ` Andrea Arcangeli
2021-01-10  3:51       ` Linus Torvalds
2021-01-10  3:51         ` Linus Torvalds
2021-01-10 19:30         ` Linus Torvalds
2021-01-10 19:30           ` Linus Torvalds
2021-01-11  1:18           ` Jason Gunthorpe
2021-01-11  7:26           ` John Hubbard
2021-01-11 12:42             ` Matthew Wilcox
2021-01-11 16:05             ` Jason Gunthorpe
2021-01-11 16:15               ` Michal Hocko [this message]
2021-01-11 19:19             ` Linus Torvalds
2021-01-11 19:19               ` Linus Torvalds
2021-01-11 22:18               ` Linus Torvalds
2021-01-11 22:18                 ` Linus Torvalds
2021-01-12 17:07                 ` Andy Lutomirski
2021-01-12 17:07                   ` Andy Lutomirski
2021-01-12 23:51                 ` Jerome Glisse
2021-01-13  2:16                 ` Matthew Wilcox
2021-01-13  2:43                   ` Linus Torvalds
2021-01-13  2:43                     ` Linus Torvalds
2021-01-13  3:31                   ` Linus Torvalds
2021-01-13  3:31                     ` Linus Torvalds
2021-01-13  8:52                     ` David Hildenbrand
2021-01-13  8:57                       ` David Hildenbrand
2021-01-13 12:32                     ` Kirill A. Shutemov
2021-01-13 12:55                       ` Matthew Wilcox
2021-01-13 19:54                         ` Linus Torvalds
2021-01-13 19:54                           ` Linus Torvalds
2021-01-13 23:54           ` Peter Xu
2021-01-11 15:52       ` Jason Gunthorpe
2021-01-15  8:59 ` David Hildenbrand
2021-01-15 18:37   ` Jason Gunthorpe
2021-01-15 19:46     ` David Hildenbrand
2021-01-15 19:53       ` Jason Gunthorpe
2021-01-16  3:40       ` John Hubbard
2021-01-16 11:42         ` David Hildenbrand

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