From: Michal Hocko <mhocko@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.com>,
linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org,
Vasily Gorbik <gor@linux.ibm.com>,
linux-sh@vger.kernel.org,
Heiko Carstens <heiko.carstens@de.ibm.com>,
linux-kernel@vger.kernel.org,
Wei Yang <richard.weiyang@gmail.com>,
linux-mm@kvack.org, Mike Rapoport <rppt@linux.vnet.ibm.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Igor Mammedov <imammedo@redhat.com>,
akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org,
Dan Williams <dan.j.williams@intel.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 02/11] s390x/mm: Fail when an altmap is used for arch_add_memory()
Date: Fri, 19 Jul 2019 08:45:10 +0200 [thread overview]
Message-ID: <20190719064510.GL30461@dhcp22.suse.cz> (raw)
In-Reply-To: <86f3ff3d-d035-a806-88b7-b8c7b77c206e@redhat.com>
On Mon 15-07-19 12:51:27, David Hildenbrand wrote:
> On 01.07.19 14:46, Michal Hocko wrote:
> > On Mon 01-07-19 09:43:06, Michal Hocko wrote:
> >> On Mon 27-05-19 13:11:43, David Hildenbrand wrote:
> >>> ZONE_DEVICE is not yet supported, fail if an altmap is passed, so we
> >>> don't forget arch_add_memory()/arch_remove_memory() when unlocking
> >>> support.
> >>
> >> Why do we need this? Sure ZONE_DEVICE is not supported for s390 and so
> >> might be the case for other arches which support hotplug. I do not see
> >> much point in adding warning to each of them.
> >
> > I would drop this one. If there is a strong reason to have something
> > like that it should come with a better explanation and it can be done on
> > top.
> >
>
> This was requested by Dan and I agree it is the right thing to do.
This is probably a matter of taste. I would argue that altmap doesn't
really equal ZONE_DEVICE. This is more a mechanism to use an alternative
memmap allocator. Sure ZONE_DEVICE is the only in tree user of the
feature but I really do not see why the arh specific code should care
about it. The lack of altmap allocator is handled in the sparse code so
this is just adding an early check which might confuse people in future.
> In
> the context of paravirtualized devices (e.g., virtio-pmem), it makes
> sense to block functionality an arch does not support.
Then block it on the config dependences.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-07-19 6:47 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-27 11:11 [PATCH v3 00/11] mm/memory_hotplug: Factor out memory block devicehandling David Hildenbrand
2019-05-27 11:11 ` [PATCH v3 01/11] mm/memory_hotplug: Simplify and fix check_hotplug_memory_range() David Hildenbrand
2019-05-30 17:53 ` Pavel Tatashin
2019-06-10 16:46 ` Oscar Salvador
2019-07-01 7:42 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 02/11] s390x/mm: Fail when an altmap is used for arch_add_memory() David Hildenbrand
2019-06-10 17:07 ` Oscar Salvador
2019-07-01 7:43 ` Michal Hocko
2019-07-01 12:46 ` Michal Hocko
2019-07-15 10:51 ` David Hildenbrand
2019-07-19 6:45 ` Michal Hocko [this message]
2019-05-27 11:11 ` [PATCH v3 03/11] s390x/mm: Implement arch_remove_memory() David Hildenbrand
2019-07-01 7:45 ` Michal Hocko
2019-07-01 12:47 ` Michal Hocko
2019-07-15 10:45 ` David Hildenbrand
2019-05-27 11:11 ` [PATCH v3 04/11] arm64/mm: Add temporary arch_remove_memory() implementation David Hildenbrand
2019-06-03 21:41 ` Wei Yang
2019-06-04 6:56 ` David Hildenbrand
2019-06-04 17:36 ` Robin Murphy
2019-06-04 17:51 ` David Hildenbrand
2019-07-01 12:48 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 05/11] drivers/base/memory: Pass a block_id to init_memory_block() David Hildenbrand
2019-06-03 21:49 ` Wei Yang
2019-06-04 6:56 ` David Hildenbrand
2019-07-01 7:56 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 06/11] mm/memory_hotplug: Allow arch_remove_pages() without CONFIG_MEMORY_HOTREMOVE David Hildenbrand
2019-05-30 17:56 ` Pavel Tatashin
2019-06-03 22:15 ` Wei Yang
2019-06-04 6:59 ` David Hildenbrand
2019-06-04 8:31 ` Wei Yang
2019-06-04 9:00 ` David Hildenbrand
2019-07-01 8:01 ` Michal Hocko
2019-07-01 12:51 ` Michal Hocko
2019-07-15 10:54 ` David Hildenbrand
2019-07-19 6:06 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 07/11] mm/memory_hotplug: Create memory block devices after arch_add_memory() David Hildenbrand
2019-05-30 21:07 ` Pavel Tatashin
2019-06-04 21:42 ` Wei Yang
2019-06-05 8:58 ` David Hildenbrand
2019-06-05 10:58 ` David Hildenbrand
2019-06-05 21:22 ` Wei Yang
2019-06-05 21:50 ` David Hildenbrand
2019-07-01 8:14 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 08/11] mm/memory_hotplug: Drop MHP_MEMBLOCK_API David Hildenbrand
2019-06-04 21:47 ` Wei Yang
2019-07-01 8:15 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 09/11] mm/memory_hotplug: Remove memory block devices before arch_remove_memory() David Hildenbrand
2019-06-04 22:07 ` Wei Yang
2019-06-05 9:00 ` David Hildenbrand
2019-07-01 8:41 ` Michal Hocko
2019-07-15 10:58 ` David Hildenbrand
2019-05-27 11:11 ` [PATCH v3 10/11] mm/memory_hotplug: Make unregister_memory_block_under_nodes() never fail David Hildenbrand
2019-06-05 21:21 ` Wei Yang
2019-06-10 16:56 ` Oscar Salvador
2019-07-01 8:51 ` Michal Hocko
2019-07-01 9:36 ` Oscar Salvador
2019-07-01 10:27 ` Michal Hocko
2019-07-15 11:10 ` David Hildenbrand
2019-07-16 8:46 ` Oscar Salvador
2019-07-16 11:08 ` David Hildenbrand
2019-07-16 11:09 ` David Hildenbrand
2019-07-19 6:05 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 11/11] mm/memory_hotplug: Remove "zone" parameter from sparse_remove_one_section David Hildenbrand
2019-06-05 21:21 ` Wei Yang
2019-06-10 16:58 ` Oscar Salvador
2019-07-01 8:52 ` Michal Hocko
2019-06-03 21:21 ` [PATCH v3 00/11] mm/memory_hotplug: Factor out memory block devicehandling Wei Yang
2019-06-03 21:40 ` David Hildenbrand
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