Patchset for fixing poison failure of THP.

I found the following problems while testing the poison of THP:
1. If the poisoned THP is failed to be split, the process could not be killed.
2. The reported address with sigbus is the address of the head page. This will make that the unexpected process on Guest OS(running on KVM) to be killed.
3. The test of poisoned tail page always fails. This is because the lru check of THP is done always, though the tail page is not set with PG_lru flag.

To resolve the above problems, I made the following patches.

Jin Dongming (3):
[PATCH 1/3] Fix splitting poisoned THP.
[PATCH 2/3] Fix the wrong reported address of poisoned THP. [PATCH 3/3] Fix unsuitable behavior for poisoned tail pages of THP.

 mm/huge_memory.c    |    7 ++++-
 mm/memory-failure.c |   84 +++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 71 insertions(+), 20 deletions(-)