From: Jason Gunthorpe <jgg@ziepe.ca>
To: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: 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, 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 v6 10/14] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning
Date: Wed, 20 Jan 2021 09:22:23 -0400 [thread overview]
Message-ID: <20210120132223.GH4605@ziepe.ca> (raw)
In-Reply-To: <20210120014333.222547-11-pasha.tatashin@soleen.com>
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.
Jason
next prev parent reply other threads:[~2021-01-20 13:22 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 [this message]
2021-01-20 14:28 ` Pavel Tatashin
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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