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
Subject: Re: [PATCH v3 5/6] mm/gup: migrate pinned pages out of movable zone
Date: Mon, 14 Dec 2020 15:19:46 +0100 [thread overview]
Message-ID: <20201214141946.GG32193@dhcp22.suse.cz> (raw)
In-Reply-To: <20201211202140.396852-6-pasha.tatashin@soleen.com>
On Fri 11-12-20 15:21:39, Pavel Tatashin wrote:
[...]
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index b593316bff3d..25c0c13ba4b1 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -386,9 +386,14 @@ enum zone_type {
> * likely to succeed, and to locally limit unmovable allocations - e.g.,
> * to increase the number of THP/huge pages. Notable special cases are:
> *
> - * 1. Pinned pages: (long-term) pinning of movable pages might
> - * essentially turn such pages unmovable. Memory offlining might
> - * retry a long time.
> + * 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 do agree with others in the thread. This is not really helping out the
current situation much. You should simply fail the pin rather than
pretend all is just fine.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-12-14 14:20 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-11 20:21 [PATCH v3 0/6] prohibit pinning pages in ZONE_MOVABLE Pavel Tatashin
2020-12-11 20:21 ` [PATCH v3 1/6] mm/gup: don't pin migrated cma pages in movable zone Pavel Tatashin
2020-12-11 20:21 ` [PATCH v3 2/6] mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_PIN Pavel Tatashin
2020-12-14 14:03 ` Michal Hocko
2020-12-15 4:37 ` Pavel Tatashin
2020-12-11 20:21 ` [PATCH v3 3/6] mm: apply per-task gfp constraints in fast path Pavel Tatashin
2020-12-14 14:09 ` Michal Hocko
2020-12-15 5:20 ` Pavel Tatashin
2020-12-15 8:25 ` Michal Hocko
2020-12-15 17:35 ` Pavel Tatashin
2020-12-11 20:21 ` [PATCH v3 4/6] mm: honor PF_MEMALLOC_PIN for all movable pages Pavel Tatashin
2020-12-14 14:17 ` Michal Hocko
2020-12-15 5:24 ` Pavel Tatashin
2020-12-15 8:27 ` Michal Hocko
2020-12-15 17:28 ` Pavel Tatashin
2020-12-11 20:21 ` [PATCH v3 5/6] mm/gup: migrate pinned pages out of movable zone Pavel Tatashin
2020-12-11 20:23 ` Jason Gunthorpe
2020-12-11 20:40 ` Pavel Tatashin
2020-12-11 20:46 ` Jason Gunthorpe
2020-12-11 21:09 ` Pavel Tatashin
2020-12-11 21:29 ` David Hildenbrand
2020-12-11 21:35 ` Pavel Tatashin
2020-12-11 21:53 ` David Hildenbrand
2020-12-11 23:00 ` Pavel Tatashin
2020-12-12 0:07 ` John Hubbard
2020-12-11 23:50 ` Jason Gunthorpe
2020-12-12 7:29 ` David Hildenbrand
2020-12-14 13:36 ` Jason Gunthorpe
2020-12-14 14:21 ` David Hildenbrand
2020-12-14 14:30 ` Michal Hocko
2020-12-14 14:19 ` Michal Hocko [this message]
2020-12-11 20:21 ` [PATCH v3 6/6] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning Pavel Tatashin
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