kernel/linux.git/Documentation/core-api, branch v6.18.21

Merge tag 'dma-mapping-6.18-2025-09-30' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux

2025-10-04T00:41:12+00:00

Pull dma-mapping updates from Marek Szyprowski: - Refactoring of DMA mapping API to physical addresses as the primary interface instead of page+offset parameters This gets much closer to Matthew Wilcox's long term wish for struct-pageless IO to cacheable DRAM and is supporting memdesc project which seeks to substantially transform how struct page works. An advantage of this approach is the possibility of introducing DMA_ATTR_MMIO, which covers existing 'dma_map_resource' flow in the common paths, what in turn lets to use recently introduced dma_iova_link() API to map PCI P2P MMIO without creating struct page Developped by Leon Romanovsky and Jason Gunthorpe - Minor clean-up by Petr Tesarik and Qianfeng Rong * tag 'dma-mapping-6.18-2025-09-30' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux: kmsan: fix missed kmsan_handle_dma() signature conversion mm/hmm: properly take MMIO path mm/hmm: migrate to physical address-based DMA mapping API dma-mapping: export new dma_*map_phys() interface xen: swiotlb: Open code map_resource callback dma-mapping: implement DMA_ATTR_MMIO for dma_(un)map_page_attrs() kmsan: convert kmsan_handle_dma to use physical addresses dma-mapping: convert dma_direct_*map_page to be phys_addr_t based iommu/dma: implement DMA_ATTR_MMIO for iommu_dma_(un)map_phys() iommu/dma: rename iommu_dma_*map_page to iommu_dma_*map_phys dma-mapping: rename trace_dma_*map_page to trace_dma_*map_phys dma-debug: refactor to use physical addresses for page mapping iommu/dma: implement DMA_ATTR_MMIO for dma_iova_link(). dma-mapping: introduce new DMA attribute to indicate MMIO memory swiotlb: Remove redundant __GFP_NOWARN dma-direct: clean up the logic in __dma_direct_alloc_pages()

Merge tag 'docs-6.18' of git://git.lwn.net/linux

2025-10-04T00:16:13+00:00

Pull documentation updates from Jonathan Corbet: "It has been a relatively busy cycle in docsland, with changes all over: - Bring the kernel memory-model docs into the Sphinx build in the "literal include" mode. - Lots of build-infrastructure work, further cleaning up long-term kernel-doc technical debt. The sphinx-pre-install tool has been converted to Python and updated for current systems. - A new tool to detect when documents have been moved and generate HTML redirects; this can be used on kernel.org (or any other site hosting the rendered docs) to avoid breaking links. - Automated processing of the YAML files describing the netlink protocol. - A significant update of the maintainer's PGP guide. ... and a seemingly endless series of typo fixes, build-problem fixes, etc" * tag 'docs-6.18' of git://git.lwn.net/linux: (193 commits) Documentation/features: Update feature lists for 6.17-rc7 docs: remove cdomain.py Documentation/process: submitting-patches: fix typo in "were do" docs: dev-tools/lkmm: Fix typo of missing file extension Documentation: trace: histogram: Convert ftrace docs cross-reference Documentation: trace: histogram-design: Wrap introductory note in note:: directive Documentation: trace: historgram-design: Separate sched_waking histogram section heading and the following diagram Documentation: trace: histogram-design: Trim trailing vertices in diagram explanation text Documentation: trace: histogram: Fix histogram trigger subsection number order docs: driver-api: fix spelling of "buses". Documentation: fbcon: Use admonition directives Documentation: fbcon: Reindent 8th step of attach/detach/unload Documentation: fbcon: Add boot options and attach/detach/unload section headings docs: filesystems: sysfs: add remaining top level sysfs directory descriptions docs: filesystems: sysfs: clarify symlink destinations in dev and bus/devices descriptions docs: filesystems: sysfs: remove top level sysfs net directory docs: maintainer: Fix ambiguous subheading formatting docs: kdoc: a few more dump_typedef() tweaks docs: kdoc: remove redundant comment stripping in dump_typedef() docs: kdoc: remove some dead code in dump_typedef() ...

mm: remove unused zpool layer

2025-09-21T21:21:59+00:00

With zswap using zsmalloc directly, there are no more in-tree users of this code. Remove it. With zpool gone, zsmalloc is now always a simple dependency and no longer something the user needs to configure. Hide CONFIG_ZSMALLOC from the user and have zswap and zram pull it in as needed. Link: https://lkml.kernel.org/r/20250829162212.208258-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Acked-by: SeongJae Park Acked-by: Yosry Ahmed Cc: Chengming Zhou Cc: Nhat Pham Cc: Vitaly Wool Signed-off-by: Andrew Morton

dma-debug: refactor to use physical addresses for page mapping

2025-09-11T22:09:51+00:00

Convert the DMA debug infrastructure from page-based to physical address-based mapping as a preparation to rely on physical address for DMA mapping routines. The refactoring renames debug_dma_map_page() to debug_dma_map_phys() and changes its signature to accept a phys_addr_t parameter instead of struct page and offset. Similarly, debug_dma_unmap_page() becomes debug_dma_unmap_phys(). A new dma_debug_phy type is introduced to distinguish physical address mappings from other debug entry types. All callers throughout the codebase are updated to pass physical addresses directly, eliminating the need for page-to-physical conversion in the debug layer. This refactoring eliminates the need to convert between page pointers and physical addresses in the debug layer, making the code more efficient and consistent with the DMA mapping API's physical address focus. Reviewed-by: Jason Gunthorpe Signed-off-by: Leon Romanovsky [mszyprow: added a fixup] Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/56d1a6769b68dfcbf8b26a75a7329aeb8e3c3b6a.1757423202.git.leonro@nvidia.com Link: https://lore.kernel.org/all/20250910052618.GH341237@unreal/

dma-mapping: introduce new DMA attribute to indicate MMIO memory

2025-09-11T22:08:07+00:00

This patch introduces the DMA_ATTR_MMIO attribute to mark DMA buffers that reside in memory-mapped I/O (MMIO) regions, such as device BARs exposed through the host bridge, which are accessible for peer-to-peer (P2P) DMA. This attribute is especially useful for exporting device memory to other devices for DMA without CPU involvement, and avoids unnecessary or potentially detrimental CPU cache maintenance calls. DMA_ATTR_MMIO is supposed to provide dma_map_resource() functionality without need to call to special function and perform branching when processing generic containers like bio_vec by the callers. Reviewed-by: Jason Gunthorpe Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/6f058ec395c5348014860dbc2eed348c17975843.1757423202.git.leonro@nvidia.com

Documentation: Add real-time to core-api

2025-08-21T20:06:08+00:00

The documents explain the design concepts behind PREEMPT_RT and highlight key differences necessary to achieve it. It also include a list of requirements that must be fulfilled to support PREEMPT_RT on a given architecture. Signed-off-by: Sebastian Andrzej Siewior [jc: tweaked "how they differ" section head] Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250815093858.930751-4-bigeasy@linutronix.de

Merge branch 'bjorn' into docs-mw

2025-08-18T16:40:16+00:00

A big set of typo fixes from Bjorn Helgaas

Documentation: Fix core-api typos

2025-08-18T16:31:19+00:00

Fix typos. Signed-off-by: Bjorn Helgaas Reviewed-by: Randy Dunlap Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250813200526.290420-5-helgaas@kernel.org

docs: folio_queue: Fix minor typo in folio_queue page

2025-08-12T18:40:15+00:00

Specifically, fix typo 'hese'-> 'these' Signed-off-by: Gopi Krishna Menon Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250810235346.4153-1-krishnagopi487@gmail.com

Documentation/printf: Use literal fwnode_handle

2025-08-11T17:00:06+00:00

When looking for fwnode_handle in the printk format documentation, it is only found in the Chinese translation: $ git grep fwnode_handle -- Documentation/*printk-formats.rst Documentation/translations/zh_CN/core-api/printk-formats.rst:用于打印fwnode_handles的消息。默认情况下是打印完整的节点名称，包括路径。 This happens because the original documentation talks about "fwnode handles", without mentioning the actual type name. Signed-off-by: Geert Uytterhoeven Tested-by: Kunwu Chan Reviewed-by: Kunwu Chan Reviewed-by: Andy Shevchenko Reviewed-by: Sakari Ailus Fixes: 3bd32d6a2ee62db3 ("lib/vsprintf: Add %pfw conversion specifier for printing fwnode names") Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/07262c55e82fc4a3e3dbe7c45713b14955271e7f.1754552156.git.geert+renesas@glider.be