These changes are based on Jason's rdma/hmm branch (5.4.0-rc1). Patch 1 was previously posted here [1] but was dropped from that orginal series. Hopefully, the tests will reduce concerns about edge conditions. I'm sure more tests could be usefully added but I thought this was a good starting point. Changes since v2: patch 1: Removed hmm_range_needs_fault() and just use hmm_range_need_fault(). Updated the change log to include that it fixes a bug where hmm_range_fault() incorrectly returned an error when no fault is requested. patch 2: Removed the confusing change log wording about DMA. Changed hmm_range_fault() to return the PFN of the zero page like any other page. patch 3: Adjusted the test code to match the new zero page behavior. Changes since v1: Rebased to Jason's rdma/hmm branch (5.4.0-rc1). Cleaned up locking for the test driver's page tables. Incorporated Christoph Hellwig's comments. [1] https://lore.kernel.org/linux-mm/20190726005650.2566-6-rcampbell@xxxxxxxxxx/ Ralph Campbell (3): mm/hmm: make full use of walk_page_range() mm/hmm: allow snapshot of the special zero page mm/hmm/test: add self tests for HMM MAINTAINERS | 3 + drivers/char/Kconfig | 11 + drivers/char/Makefile | 1 + drivers/char/hmm_dmirror.c | 1566 ++++++++++++++++++++++++ include/Kbuild | 1 + include/uapi/linux/hmm_dmirror.h | 74 ++ mm/hmm.c | 136 +- tools/testing/selftests/vm/.gitignore | 1 + tools/testing/selftests/vm/Makefile | 3 + tools/testing/selftests/vm/config | 3 + tools/testing/selftests/vm/hmm-tests.c | 1311 ++++++++++++++++++++ tools/testing/selftests/vm/run_vmtests | 16 + tools/testing/selftests/vm/test_hmm.sh | 97 ++ 13 files changed, 3158 insertions(+), 65 deletions(-) create mode 100644 drivers/char/hmm_dmirror.c create mode 100644 include/uapi/linux/hmm_dmirror.h create mode 100644 tools/testing/selftests/vm/hmm-tests.c create mode 100755 tools/testing/selftests/vm/test_hmm.sh -- 2.20.1
