From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: Michal Hocko <mhocko@suse.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
David Hildenbrand <david@redhat.com>,
Oscar Salvador <osalvador@suse.de>,
Dan Williams <dan.j.williams@intel.com>,
Sasha Levin <sashal@kernel.org>,
Tyler Hicks <tyhicks@linux.microsoft.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
mike.kravetz@oracle.com, Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>, Jason Gunthorpe <jgg@ziepe.ca>,
Peter Zijlstra <peterz@infradead.org>,
Mel Gorman <mgorman@suse.de>,
Matthew Wilcox <willy@infradead.org>,
David Rientjes <rientjes@google.com>,
John Hubbard <jhubbard@nvidia.com>,
Linux Doc Mailing List <linux-doc@vger.kernel.org>,
Ira Weiny <ira.weiny@intel.com>,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v4 05/10] mm/gup: migrate pinned pages out of movable zone
Date: Wed, 13 Jan 2021 14:14:11 -0500 [thread overview]
Message-ID: <CA+CK2bBLZu3X5P3qkaTV7To4qx2W79Y1MQdpJM3134LtkzkhXA@mail.gmail.com> (raw)
In-Reply-To: <20201218130825.GY32193@dhcp22.suse.cz>
On Fri, Dec 18, 2020 at 8:08 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Fri 18-12-20 07:24:53, Pavel Tatashin wrote:
> > On Fri, Dec 18, 2020 at 4:43 AM Michal Hocko <mhocko@suse.com> wrote:
> > >
> > > On Thu 17-12-20 13:52:38, Pavel Tatashin wrote:
> > > > + * 1. Pinned pages: (long-term) pinning of movable pages is avoided
> > > > + * when pages are pinned and faulted, but it is still possible that
> > > > + * address space already has pages in ZONE_MOVABLE at the time when
> > > > + * pages are pinned (i.e. user has touches that memory before
> > > > + * pinning). In such case we try to migrate them to a different zone,
> > > > + * but if migration fails the pages can still end-up pinned in
> > > > + * ZONE_MOVABLE. In such case, memory offlining might retry a long
> > > > + * time and will only succeed once user application unpins pages.
> > >
> > > I still dislike this. Pinning can fail so there shouldn't be any reasons
> > > to break MOVABLE constrain for something that can be handled. If
> > > anything there should be a very good reasoning behind this decision
> > > documented.
> >
> > This is basically current behaviour, after patch 8, we can never pin
> > pages in the movable zone, so I will update this comment in that
> > patch.
>
> Then it would be much easier for review to state that the existing
> behavior is unchanged and do not update this comment just to remove it
> in a later patch. Because this patch should be straightforward change of
> the condition which pages to migrate (+some renaming which should be
> reasonably easy to follow).
Makes sense, I will update this comment correctly right away when the
behaviour changes.
next prev parent reply other threads:[~2021-01-13 19:15 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-17 18:52 [PATCH v4 00/10] prohibit pinning pages in ZONE_MOVABLE Pavel Tatashin
2020-12-17 18:52 ` [PATCH v4 01/10] mm/gup: don't pin migrated cma pages in movable zone Pavel Tatashin
2020-12-17 18:52 ` [PATCH v4 02/10] mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_PIN Pavel Tatashin
2020-12-17 18:52 ` [PATCH v4 03/10] mm: apply per-task gfp constraints in fast path Pavel Tatashin
2020-12-18 9:36 ` Michal Hocko
2020-12-18 12:23 ` Pavel Tatashin
2020-12-17 18:52 ` [PATCH v4 04/10] mm: honor PF_MEMALLOC_PIN for all movable pages Pavel Tatashin
2020-12-17 18:52 ` [PATCH v4 05/10] mm/gup: migrate pinned pages out of movable zone Pavel Tatashin
2020-12-18 9:43 ` Michal Hocko
2020-12-18 12:24 ` Pavel Tatashin
2020-12-18 13:08 ` Michal Hocko
2021-01-13 19:14 ` Pavel Tatashin [this message]
2020-12-17 18:52 ` [PATCH v4 06/10] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning Pavel Tatashin
2020-12-18 9:44 ` Michal Hocko
2020-12-17 18:52 ` [PATCH v4 07/10] mm/gup: change index type to long as it counts pages Pavel Tatashin
2020-12-18 9:50 ` Michal Hocko
2020-12-18 12:32 ` Pavel Tatashin
2020-12-17 18:52 ` [PATCH v4 08/10] mm/gup: limit number of gup migration failures, honor failures Pavel Tatashin
2020-12-17 20:50 ` Jason Gunthorpe
2020-12-17 22:02 ` Pavel Tatashin
2020-12-18 14:19 ` Jason Gunthorpe
2021-01-13 19:43 ` Pavel Tatashin
2021-01-13 19:55 ` Jason Gunthorpe
2021-01-13 20:05 ` Pavel Tatashin
2021-01-13 23:40 ` Jason Gunthorpe
2021-01-15 18:10 ` Pavel Tatashin
2021-01-15 18:40 ` Jason Gunthorpe
2020-12-18 10:46 ` Michal Hocko
2020-12-18 12:43 ` Pavel Tatashin
2020-12-18 13:04 ` David Hildenbrand
2020-12-18 13:14 ` Michal Hocko
2021-01-13 19:49 ` Pavel Tatashin
2020-12-17 18:52 ` [PATCH v4 09/10] selftests/vm: test flag is broken Pavel Tatashin
2020-12-18 9:06 ` John Hubbard
2020-12-18 9:11 ` John Hubbard
2020-12-17 18:52 ` [PATCH v4 10/10] selftests/vm: test faulting in kernel, and verify pinnable pages Pavel Tatashin
2020-12-19 5:57 ` John Hubbard
2020-12-19 15:22 ` Pavel Tatashin
2020-12-19 23:51 ` John Hubbard
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