mm/hmm: use reference counting for HMM struct

Every time I read the code to check that the HMM structure does not vanish
before it should thanks to the many lock protecting its removal i get a
headache.  Switch to reference counting instead it is much easier to
follow and harder to break.  This also remove some code that is no longer
needed with refcounting.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Jérôme Glisse <[email protected]>
Reviewed-by: Ralph Campbell <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Dan Carpenter <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Souptick Joarder <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions