mm/hotplug: make remove_memory() interface usable

Presently the remove_memory() interface is inherently broken.  It tries
to remove memory but panics if some memory is not offline.  The problem
is that it is impossible to ensure that all memory blocks are offline as
this function also takes lock_device_hotplug that is required to change
memory state via sysfs.

So, between calling this function and offlining all memory blocks there
is always a window when lock_device_hotplug is released, and therefore,
there is always a chance for a panic during this window.

Make this interface to return an error if memory removal fails.  This
way it is safe to call this function without panicking machine, and also
makes it symmetric to add_memory() which already returns an error.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Pavel Tatashin <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Fengguang Wu <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: James Morris <[email protected]>
Cc: Jérôme Glisse <[email protected]>
Cc: Keith Busch <[email protected]>
Cc: Ross Zwisler <[email protected]>
Cc: Sasha Levin <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Yaowei Bai <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions