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, jmorris@namei.org
Subject: [PATCH v9 10/14] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning
Date: Mon, 1 Feb 2021 10:38:23 -0500 [thread overview]
Message-ID: <20210201153827.444374-11-pasha.tatashin@soleen.com> (raw)
In-Reply-To: <20210201153827.444374-1-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>
Acked-by: Michal Hocko <mhocko@suse.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:[~2021-02-01 15:44 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-01 15:38 [PATCH v9 00/14] prohibit pinning pages in ZONE_MOVABLE Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 01/14] mm/gup: don't pin migrated cma pages in movable zone Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 02/14] mm/gup: check every subpage of a compound page during isolation Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 03/14] mm/gup: return an error on migration failure Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 04/14] mm/gup: check for isolation errors Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 05/14] mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_PIN Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 06/14] mm: apply per-task gfp constraints in fast path Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 07/14] mm: honor PF_MEMALLOC_PIN for all movable pages Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 08/14] mm/gup: do not migrate zero page Pavel Tatashin
2021-02-02 2:41 ` kernel test robot
2021-02-02 4:05 ` Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 09/14] mm/gup: migrate pinned pages out of movable zone Pavel Tatashin
2021-02-01 15:38 ` Pavel Tatashin [this message]
2021-02-01 15:38 ` [PATCH v9 11/14] mm/gup: change index type to long as it counts pages Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 12/14] mm/gup: longterm pin migration cleanup Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 13/14] selftests/vm: gup_test: fix test flag Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 14/14] selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages Pavel Tatashin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210201153827.444374-11-pasha.tatashin@soleen.com \
--to=pasha.tatashin@soleen.com \
--cc=akpm@linux-foundation.org \
--cc=dan.j.williams@intel.com \
--cc=david@redhat.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=ira.weiny@intel.com \
--cc=jgg@ziepe.ca \
--cc=jhubbard@nvidia.com \
--cc=jmorris@namei.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=mhocko@suse.com \
--cc=mike.kravetz@oracle.com \
--cc=mingo@redhat.com \
--cc=osalvador@suse.de \
--cc=peterz@infradead.org \
--cc=rientjes@google.com \
--cc=rostedt@goodmis.org \
--cc=sashal@kernel.org \
--cc=tyhicks@linux.microsoft.com \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).