From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: pasha.tatashin@soleen.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz,
mhocko@suse.com, 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: [PATCH v4 06/10] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning
Date: Thu, 17 Dec 2020 13:52:39 -0500 [thread overview]
Message-ID: <20201217185243.3288048-7-pasha.tatashin@soleen.com> (raw)
In-Reply-To: <20201217185243.3288048-1-pasha.tatashin@soleen.com>
Document the special handling of page pinning when ZONE_MOVABLE present.
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Suggested-by: David Hildenbrand <david@redhat.com>
---
Documentation/admin-guide/mm/memory-hotplug.rst | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst
index 5c4432c96c4b..c6618f99f765 100644
--- a/Documentation/admin-guide/mm/memory-hotplug.rst
+++ b/Documentation/admin-guide/mm/memory-hotplug.rst
@@ -357,6 +357,15 @@ creates ZONE_MOVABLE as following.
Unfortunately, there is no information to show which memory block belongs
to ZONE_MOVABLE. This is TBD.
+.. note::
+ Techniques that rely on long-term pinnings of memory (especially, RDMA and
+ vfio) are fundamentally problematic with ZONE_MOVABLE and, therefore, memory
+ hot remove. Pinned pages cannot reside on ZONE_MOVABLE, to guarantee that
+ memory can still get hot removed - be aware that pinning can fail even if
+ there is plenty of free memory in ZONE_MOVABLE. In addition, using
+ ZONE_MOVABLE might make page pinning more expensive, because pages have to be
+ migrated off that zone first.
+
.. _memory_hotplug_how_to_offline_memory:
How to offline memory
--
2.25.1
next prev parent reply other threads:[~2020-12-17 18:55 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
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 ` Pavel Tatashin [this message]
2020-12-18 9:44 ` [PATCH v4 06/10] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning 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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