kernel/linux.git/lib/test_hmm.c, branch v6.18.21

lib/test_hmm: drop redundant conversion to bool

2025-09-13T23:55:13+00:00

The result of integer comparison already evaluates to bool. No need for explicit conversion. No functional impact. Link: https://lkml.kernel.org/r/20250819070457.486348-1-zhao.xichao@vivo.com Signed-off-by: Xichao Zhao Reviewed-by: Alistair Popple Cc: Jason Gunthorpe Cc: Leon Romanovsky Signed-off-by: Andrew Morton

lib/test_hmm: reduce stack usage

2025-07-10T05:42:05+00:00

The various test ioctl handlers use arrays of 64 integers that add up to 1KiB of stack data, which in turn leads to exceeding the warning limit in some configurations: lib/test_hmm.c:935:12: error: stack frame size (1408) exceeds limit (1280) in 'dmirror_migrate_to_device' [-Werror,-Wframe-larger-than] Use half the size for these arrays, in order to stay under the warning limits. The code can already deal with arbitrary lengths, but this may be a little less efficient. Link: https://lkml.kernel.org/r/20250610092159.2639515-1-arnd@kernel.org Signed-off-by: Arnd Bergmann Cc: Alistair Popple Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Jeff Johnson Cc: Jerome Glisse Cc: Thorsten Blum Signed-off-by: Andrew Morton

mm: allow compound zone device pages

2025-03-18T05:06:39+00:00

Zone device pages are used to represent various type of device memory managed by device drivers. Currently compound zone device pages are not supported. This is because MEMORY_DEVICE_FS_DAX pages are the only user of higher order zone device pages and have their own page reference counting. A future change will unify FS DAX reference counting with normal page reference counting rules and remove the special FS DAX reference counting. Supporting that requires compound zone device pages. Supporting compound zone device pages requires compound_head() to distinguish between head and tail pages whilst still preserving the special struct page fields that are specific to zone device pages. A tail page is distinguished by having bit zero being set in page->compound_head, with the remaining bits pointing to the head page. For zone device pages page->compound_head is shared with page->pgmap. The page->pgmap field must be common to all pages within a folio, even if the folio spans memory sections. Therefore pgmap is the same for both head and tail pages and can be moved into the folio and we can use the standard scheme to find compound_head from a tail page. Link: https://lkml.kernel.org/r/67055d772e6102accf85161d0b57b0b3944292bf.1740713401.git-series.apopple@nvidia.com Signed-off-by: Alistair Popple Signed-off-by: Balbir Singh Reviewed-by: Jason Gunthorpe Reviewed-by: Dan Williams Acked-by: David Hildenbrand Tested-by: Alison Schofield Cc: Alexander Gordeev Cc: Asahi Lina Cc: Bjorn Helgaas Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Christoph Hellwig Cc: Chunyan Zhang Cc: "Darrick J. Wong" Cc: Dave Chinner Cc: Dave Hansen Cc: Dave Jiang Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Huacai Chen Cc: Ira Weiny Cc: Jan Kara Cc: Jason Gunthorpe Cc: John Hubbard Cc: linmiaohe Cc: Logan Gunthorpe Cc: Matthew Wilcow (Oracle) Cc: Michael "Camp Drill Sergeant" Ellerman Cc: Nicholas Piggin Cc: Peter Xu Cc: Sven Schnelle Cc: Ted Ts'o Cc: Vasily Gorbik Cc: Vishal Verma Cc: Vivek Goyal Cc: WANG Xuerui Cc: Will Deacon Signed-off-by: Andrew Morton

lib/test_hmm: make dmirror_atomic_map() consume a single page

2025-03-17T07:05:29+00:00

Patch series "mm: cleanups for device-exclusive entries (hmm)", v2. Some smaller device-exclusive cleanups I have lying around. This patch (of 5): The caller now always passes a single page; let's simplify, and return "0" on success. Link: https://lkml.kernel.org/r/20250226132257.2826043-1-david@redhat.com Link: https://lkml.kernel.org/r/20250226132257.2826043-2-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Alistair Popple Cc: Jason Gunthorpe Cc: Jérôme Glisse Signed-off-by: Andrew Morton

mm/rmap: convert make_device_exclusive_range() to make_device_exclusive()

2025-03-17T05:05:57+00:00

The single "real" user in the tree of make_device_exclusive_range() always requests making only a single address exclusive. The current implementation is hard to fix for properly supporting anonymous THP / large folios and for avoiding messing with rmap walks in weird ways. So let's always process a single address/page and return folio + page to minimize page -> folio lookups. This is a preparation for further changes. Reject any non-anonymous or hugetlb folios early, directly after GUP. While at it, extend the documentation of make_device_exclusive() to clarify some things. Link: https://lkml.kernel.org/r/20250210193801.781278-4-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Simona Vetter Reviewed-by: Alistair Popple Tested-by: Alistair Popple Cc: Alex Shi Cc: Danilo Krummrich Cc: Dave Airlie Cc: Jann Horn Cc: Jason Gunthorpe Cc: Jerome Glisse Cc: John Hubbard Cc: Jonathan Corbet Cc: Karol Herbst Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Lyude Cc: "Masami Hiramatsu (Google)" Cc: Oleg Nesterov Cc: Pasha Tatashin Cc: Peter Xu Cc: Peter Zijlstra (Intel) Cc: SeongJae Park Cc: Vlastimil Babka Cc: Yanteng Si Cc: Barry Song Signed-off-by: Andrew Morton

lib: test_hmm: use min() to improve dmirror_exclusive()

2024-09-02T03:25:52+00:00

Use min() to simplify the dmirror_exclusive() function and improve its readability. Link: https://lkml.kernel.org/r/20240726131245.161695-1-thorsten.blum@toblux.com Signed-off-by: Thorsten Blum Reviewed-by: David Hildenbrand Cc: Jérôme Glisse Signed-off-by: Andrew Morton

lib: test_hmm: add missing MODULE_DESCRIPTION() macro

2024-07-04T02:30:05+00:00

make allmodconfig && make W=1 C=1 reports: WARNING: modpost: missing MODULE_DESCRIPTION() in lib/test_hmm.o Add the missing invocation of the MODULE_DESCRIPTION() macro. Link: https://lkml.kernel.org/r/20240531-lib-md-test_hmm-v1-1-e4aa17daa57b@quicinc.com Signed-off-by: Jeff Johnson Cc: Jérôme Glisse Signed-off-by: Andrew Morton

lib/test_hmm.c: handle src_pfns and dst_pfns allocation failure

2024-04-26T03:55:48+00:00

The kcalloc() in dmirror_device_evict_chunk() will return null if the physical memory has run out. As a result, if src_pfns or dst_pfns is dereferenced, the null pointer dereference bug will happen. Moreover, the device is going away. If the kcalloc() fails, the pages mapping a chunk could not be evicted. So add a __GFP_NOFAIL flag in kcalloc(). Finally, as there is no need to have physically contiguous memory, Switch kcalloc() to kvcalloc() in order to avoid failing allocations. Link: https://lkml.kernel.org/r/20240312005905.9939-1-duoming@zju.edu.cn Fixes: b2ef9f5a5cb3 ("mm/hmm/test: add selftest driver for HMM") Signed-off-by: Duoming Zhou Cc: Jérôme Glisse Signed-off-by: Andrew Morton

lib: replace kmap() with kmap_local_page()

2023-08-18T17:18:50+00:00

kmap() has been deprecated in favor of the kmap_local_page() due to high cost, restricted mapping space, the overhead of a global lock for synchronization, and making the process sleep in the absence of free slots. kmap_local_page() is faster than kmap() and offers thread-local and CPU-local mappings, take pagefaults in a local kmap region and preserves preemption by saving the mappings of outgoing tasks and restoring those of the incoming one during a context switch. The mappings are kept thread local in the functions “dmirror_do_read” and “dmirror_do_write” in test_hmm.c Therefore, replace kmap() with kmap_local_page() and use mempcy_from/to_page() to avoid open coding kmap_local_page() + memcpy() + kunmap_local(). Remove the unused variable “tmp”. Link: https://lkml.kernel.org/r/20230610175712.GA348514@sumitra.com Signed-off-by: Sumitra Sharma Suggested-by: Fabio M. De Francesco Reviewed-by: Fabio M. De Francesco Reviewed-by: Ira Weiny Cc: Deepak R Varma Cc: Jérôme Glisse Signed-off-by: Andrew Morton

hmm-tests: add test for migrate_device_range()

2022-10-13T01:51:50+00:00

Link: https://lkml.kernel.org/r/a73cf109de0224cfd118d22be58ddebac3ae2897.1664366292.git-series.apopple@nvidia.com Signed-off-by: Alistair Popple Cc: Jason Gunthorpe Cc: Ralph Campbell Cc: John Hubbard Cc: Alex Sierra Cc: Felix Kuehling Cc: Alex Deucher Cc: Ben Skeggs Cc: Christian König Cc: Dan Williams Cc: David Hildenbrand Cc: "Huang, Ying" Cc: Lyude Paul Cc: Matthew Wilcox Cc: Michael Ellerman Cc: Yang Shi Cc: Zi Yan Signed-off-by: Andrew Morton