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author | David Hildenbrand <david@redhat.com> | 2020-11-12 16:38:13 +0300 |
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committer | Michael S. Tsirkin <mst@redhat.com> | 2020-12-19 00:14:27 +0300 |
commit | 8dc4bb58a146655eb057247d7c9d19e73928715b (patch) | |
tree | 47829ea9a12e73d2872a1401f98e78f4743126e2 /drivers/virtio/virtio_mem.c | |
parent | faa45ff4ce885af93a3233a408c5a74b2943226b (diff) | |
download | linux-8dc4bb58a146655eb057247d7c9d19e73928715b.tar.xz |
mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block
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.
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20201112133815.13332-28-david@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers/virtio/virtio_mem.c')
0 files changed, 0 insertions, 0 deletions