[0/2] A couple hugetlbfs fixes

Message

Mike Kravetz March 8, 2019, 10:48 p.m. UTC

I stumbled on these two hugetlbfs issues while looking at other things:
- The 'restore reserve' functionality at page free time should not
  be adjusting subpool counts.
- A BUG can be triggered (not easily) due to temporarily mapping a
  page before doing a COW.

Both are described in detail in the commit message of the patches.
I would appreciate comments from Davidlohr Bueso as one patch is
directly related to code he added in commit 8382d914ebf7.

I did not cc stable as the first problem has been around since reserves
were added to hugetlbfs and nobody has noticed.  The second is very hard
to hit/reproduce.

Mike Kravetz (2):
  huegtlbfs: on restore reserve error path retain subpool reservation
  hugetlb: use same fault hash key for shared and private mappings

 mm/hugetlb.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)