Hi Andrew,
Here is another device-dax fix that requires touching some mm code. When device-dax is operating in huge-page mode we want it to behave like hugetlbfs and fail attempts to split vmas into unaligned ranges. It would be messy to teach the munmap path about device-dax alignment constraints in the same (hstate) way that hugetlbfs communicates this constraint. Instead, these patches introduce a new ->split() vm operation.
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Dan Williams (2): mm, hugetlbfs: introduce ->split() to vm_operations_struct device-dax: implement ->split() to catch invalid munmap attempts
drivers/dax/device.c | 12 ++++++++++++ include/linux/mm.h | 1 + mm/hugetlb.c | 8 ++++++++ mm/mmap.c | 8 +++++--- 4 files changed, 26 insertions(+), 3 deletions(-)