HMM patches for 5.3-rc

Fix the locking around nouveau's use of the hmm_range_* APIs. It works
 correctly in the success case, but many of the the edge cases have missing
 unlocks or double unlocks.
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Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

Pull HMM fixes from Jason Gunthorpe:
 "Fix the locking around nouveau's use of the hmm_range_* APIs. It works
  correctly in the success case, but many of the the edge cases have
  missing unlocks or double unlocks.

  The diffstat is a bit big as Christoph did a comprehensive job to move
  the obsolete API from the core header and into the driver before
  fixing its flow, but the risk of regression from this code motion is
  low"

* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
  nouveau: unlock mmap_sem on all errors from nouveau_range_fault
  nouveau: remove the block parameter to nouveau_range_fault
  mm/hmm: move hmm_vma_range_done and hmm_vma_fault to nouveau
  mm/hmm: always return EBUSY for invalid ranges in hmm_range_{fault,snapshot}

Documentation/vm/hmm.rst

@@ -237,7 +237,7 @@ The usage pattern is::
       ret = hmm_range_snapshot(&range);
       if (ret) {
           up_read(&mm->mmap_sem);
-          if (ret == -EAGAIN) {
+          if (ret == -EBUSY) {
             /*
              * No need to check hmm_range_wait_until_valid() return value
              * on retry we will get proper error with hmm_range_snapshot()