From: Michal Hocko <mhocko@suse.com>
To: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, vbabka@suse.cz, david@redhat.com,
osalvador@suse.de, dan.j.williams@intel.com, sashal@kernel.org,
tyhicks@linux.microsoft.com, iamjoonsoo.kim@lge.com,
mike.kravetz@oracle.com, rostedt@goodmis.org, mingo@redhat.com,
jgg@ziepe.ca, peterz@infradead.org, mgorman@suse.de,
willy@infradead.org, rientjes@google.com, jhubbard@nvidia.com,
linux-doc@vger.kernel.org, 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: Fri, 18 Dec 2020 10:43:24 +0100 [thread overview]
Message-ID: <20201218094324.GT32193@dhcp22.suse.cz> (raw)
In-Reply-To: <20201217185243.3288048-6-pasha.tatashin@soleen.com>
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.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-12-18 9:44 UTC|newest]
Thread overview: 50+ 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
2020-12-18 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 [this message]
2020-12-18 12:24 ` Pavel Tatashin
2020-12-18 12:24 ` Pavel Tatashin
2020-12-18 13:08 ` Michal Hocko
2021-01-13 19:14 ` Pavel Tatashin
2021-01-13 19:14 ` Pavel Tatashin
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
2020-12-18 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
2020-12-17 22:02 ` Pavel Tatashin
2020-12-18 14:19 ` Jason Gunthorpe
2021-01-13 19:43 ` Pavel Tatashin
2021-01-13 19:43 ` Pavel Tatashin
2021-01-13 19:55 ` Jason Gunthorpe
2021-01-13 20:05 ` Pavel Tatashin
2021-01-13 20:05 ` Pavel Tatashin
2021-01-13 23:40 ` Jason Gunthorpe
2021-01-15 18:10 ` Pavel Tatashin
2021-01-15 18:10 ` 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 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
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 15:22 ` Pavel Tatashin
2020-12-19 23:51 ` John Hubbard
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