On Wed, Jun 14, 2023 at 02:19:00PM +0800, Wupeng Ma wrote:
From: David Hildenbrand david@redhat.com
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
mm/memory_hotplug.c | 105 +++++++++++++++++++++++++++++++++++++------- 1 file changed, 89 insertions(+), 16 deletions(-)
As you forwarded this patch on, you too need to sign-off on it.
Also, what is the git id of the commit in Linus's tree?
thanks,
greg k-h