Messages in this thread | | | Subject | Re: [PATCH v2 27/29] mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block | From | David Hildenbrand <> | Date | Wed, 18 Nov 2020 09:59:45 +0100 |
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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
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