From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
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>,
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 v6 10/14] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning
Date: Wed, 20 Jan 2021 09:28:56 -0500 [thread overview]
Message-ID: <CA+CK2bAcbLzWTC3b=FqtSODG2ZWEK56AoWAQKnPWbJTzn3w6+g@mail.gmail.com> (raw)
In-Reply-To: <20210120132223.GH4605@ziepe.ca>
On Wed, Jan 20, 2021 at 8:22 AM Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
> On Tue, Jan 19, 2021 at 08:43:29PM -0500, Pavel Tatashin wrote:
> > +.. 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.
>
> Just to point out, if anyone is using RDMA/etc with hotplug memory,
> this series is likekly going to be a major regression for those users.
Right: one is because we now prohibit pinning any pages in a movable
zone, second reason is because we now check every page during
migration that fixes an existing bug.
>
> Jason
next prev parent reply other threads:[~2021-01-20 14:29 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 1:43 [PATCH v6 00/14] prohibit pinning pages in ZONE_MOVABLE Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 01/14] mm/gup: don't pin migrated cma pages in movable zone Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 02/14] mm/gup: check every subpage of a compound page during isolation Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 03/14] mm/gup: return an error on migration failure Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 04/14] mm/gup: check for isolation errors Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 05/14] mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_PIN Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 06/14] mm: apply per-task gfp constraints in fast path Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 07/14] mm: honor PF_MEMALLOC_PIN for all movable pages Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 08/14] mm/gup: do not migrate zero page Pavel Tatashin
2021-01-20 13:14 ` Jason Gunthorpe
2021-01-20 14:26 ` Pavel Tatashin
2021-01-25 14:28 ` Jason Gunthorpe
2021-01-25 15:38 ` Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 09/14] mm/gup: migrate pinned pages out of movable zone Pavel Tatashin
2021-01-20 17:50 ` kernel test robot
2021-01-20 21:31 ` Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 10/14] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning Pavel Tatashin
2021-01-20 13:22 ` Jason Gunthorpe
2021-01-20 14:28 ` Pavel Tatashin [this message]
2021-01-20 1:43 ` [PATCH v6 11/14] mm/gup: change index type to long as it counts pages Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 12/14] mm/gup: longterm pin migration cleaup Pavel Tatashin
2021-01-20 13:19 ` Jason Gunthorpe
2021-01-20 14:17 ` Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 13/14] selftests/vm: test flag is broken Pavel Tatashin
2021-01-20 1:43 ` [PATCH v6 14/14] selftests/vm: test faulting in kernel, and verify pinnable pages Pavel Tatashin
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