On Thu, 12 Nov 2020 14:38:13 +0100 David Hildenbrand <david@xxxxxxxxxx> 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. Acked-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
