Re: [PATCH v3 07/11] mm/memory_hotplug: Create memory block devices after arch_add_memory()

From: Pavel Tatashin
Date: Thu May 30 2019 - 17:10:57 EST

On Mon, May 27, 2019 at 7:12 AM David Hildenbrand <david@xxxxxxxxxx> wrote:
> Only memory to be added to the buddy and to be onlined/offlined by
> user space using /sys/devices/system/memory/... needs (and should have!)
> memory block devices.
> Factor out creation of memory block devices. Create all devices after
> arch_add_memory() succeeded. We can later drop the want_memblock parameter,
> because it is now effectively stale.
> Only after memory block devices have been added, memory can be onlined
> by user space. This implies, that memory is not visible to user space at
> all before arch_add_memory() succeeded.
> While at it
> - use WARN_ON_ONCE instead of BUG_ON in moved unregister_memory()
> - introduce find_memory_block_by_id() to search via block id
> - Use find_memory_block_by_id() in init_memory_block() to catch
> duplicates
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: "mike.travis@xxxxxxx" <mike.travis@xxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Andrew Banman <andrew.banman@xxxxxxx>
> Cc: Oscar Salvador <osalvador@xxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
> Cc: Qian Cai <cai@xxxxxx>
> Cc: Wei Yang <richard.weiyang@xxxxxxxxx>
> Cc: Arun KS <arunks@xxxxxxxxxxxxxx>
> Cc: Mathieu Malaterre <malat@xxxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>

Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>