From: David Hildenbrand <david@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
"Michael S . Tsirkin" <mst@redhat.com>,
Wei Yang <richard.weiyang@linux.alibaba.com>,
Jason Wang <jasowang@redhat.com>,
Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
Michal Hocko <mhocko@kernel.org>,
Oscar Salvador <osalvador@suse.de>
Subject: Re: [PATCH v2 27/29] mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block
Date: Wed, 18 Nov 2020 09:59:45 +0100 [thread overview]
Message-ID: <842683af-0a1e-78ea-5b94-178eaf8f3239@redhat.com> (raw)
In-Reply-To: <20201117205301.bcef9773f3557a764d17b8df@linux-foundation.org>
On 18.11.20 05:53, Andrew Morton wrote:
> On Thu, 12 Nov 2020 14:38:13 +0100 David Hildenbrand <david@redhat.com> wrote:
>
>> virtio-mem soon wants to use offline_and_remove_memory() memory that
>> exceeds a single Linux memory block (memory_block_size_bytes()). Let's
>> remove that restriction.
>>
>> Let's remember the old state and try to restore that if anything goes
>> wrong. While re-onlining can, in general, fail, it's highly unlikely to
>> happen (usually only when a notifier fails to allocate memory, and these
>> are rather rare).
>>
>> This will be used by virtio-mem to offline+remove memory ranges that are
>> bigger than a single memory block - for example, with a device block
>> size of 1 GiB (e.g., gigantic pages in the hypervisor) and a Linux memory
>> block size of 128MB.
>>
>> While we could compress the state into 2 bit, using 8 bit is much
>> easier.
>>
>> This handling is similar, but different to acpi_scan_try_to_offline():
>>
>> a) We don't try to offline twice. I am not sure if this CONFIG_MEMCG
>> optimization is still relevant - it should only apply to ZONE_NORMAL
>> (where we have no guarantees). If relevant, we can always add it.
>>
>> b) acpi_scan_try_to_offline() simply onlines all memory in case
>> something goes wrong. It doesn't restore previous online type. Let's do
>> that, so we won't overwrite what e.g., user space configured.
>>
>> ...
>>
>
> uint8_t is a bit of a mouthful. u8 is less typing ;) Doesn't matter.
In case I have to resend, I'll change it :)
>
> Acked-by: Andrew Morton <akpm@linux-foundation.org>
Thanks!
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-11-18 9:00 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 13:37 [PATCH v2 00/29] virtio-mem: Big Block Mode (BBM) David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 01/29] virtio-mem: determine nid only once using memory_add_physaddr_to_nid() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 02/29] virtio-mem: more precise calculation in virtio_mem_mb_state_prepare_next_mb() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 03/29] virtio-mem: simplify MAX_ORDER - 1 / pageblock_order handling David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 04/29] virtio-mem: drop rc2 in virtio_mem_mb_plug_and_add() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 05/29] virtio-mem: use "unsigned long" for nr_pages when fake onlining/offlining David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 06/29] virtio-mem: factor out calculation of the bit number within the subblock bitmap David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 07/29] virtio-mem: print debug messages from virtio_mem_send_*_request() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 08/29] virtio-mem: factor out fake-offlining into virtio_mem_fake_offline() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 09/29] virtio-mem: factor out handling of fake-offline pages in memory notifier David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 10/29] virtio-mem: retry fake-offlining via alloc_contig_range() on ZONE_MOVABLE David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 11/29] virtio-mem: generalize check for added memory David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 12/29] virtio-mem: generalize virtio_mem_owned_mb() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 13/29] virtio-mem: generalize virtio_mem_overlaps_range() David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 14/29] virtio-mem: drop last_mb_id David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 15/29] virtio-mem: don't always trigger the workqueue when offlining memory David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 16/29] virtio-mem: generalize handling when memory is getting onlined deferred David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 17/29] virito-mem: document Sub Block Mode (SBM) David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 18/29] virtio-mem: memory block states are specific to " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 19/29] virito-mem: subblock " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 20/29] virtio-mem: nb_sb_per_mb and subblock_size " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 21/29] virtio-mem: memory block ids " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 22/29] virito-mem: existing (un)plug functions " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 23/29] virtio-mem: memory notifier callbacks " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 24/29] virtio-mem: factor out adding/removing memory from Linux David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 25/29] virtio-mem: Big Block Mode (BBM) memory hotplug David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 26/29] virtio-mem: allow to force Big Block Mode (BBM) and set the big block size David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 27/29] mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block David Hildenbrand
2020-11-18 4:53 ` Andrew Morton
2020-11-18 8:59 ` David Hildenbrand [this message]
2020-11-12 13:38 ` [PATCH v2 28/29] virtio-mem: Big Block Mode (BBM) - basic memory hotunplug David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 29/29] virtio-mem: Big Block Mode (BBM) - safe " David Hildenbrand
2020-11-18 9:00 ` [PATCH v2 00/29] virtio-mem: Big Block Mode (BBM) Michael S. Tsirkin
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