kernel/linux.git/include/linux/memremap.h, branch v6.18.21

mm/memremap: remove unused get_dev_pagemap() parameter

2025-09-21T21:22:21+00:00

GUP no longer uses get_dev_pagemap(). As it was the only user of the get_dev_pagemap() pgmap caching feature it can be removed. Link: https://lkml.kernel.org/r/20250903225926.34702-2-apopple@nvidia.com Signed-off-by: Alistair Popple Acked-by: David Hildenbrand Reviewed-by: Jason Gunthorpe Reviewed-by: Dan Williams Cc: John Hubbard Cc: Oscar Salvador Cc: Peter Xu Signed-off-by: Andrew Morton

mm: add folio_is_pci_p2pdma()

2025-09-13T23:55:10+00:00

Reimplement is_pci_p2pdma_page() in terms of folio_is_pci_p2pdma(). Moves the page_folio() call from inside page_pgmap() to is_pci_p2pdma_page(). This removes a page_folio() call from try_grab_folio() which already has a folio and can pass it in. Link: https://lkml.kernel.org/r/20250805172307.1302730-12-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Shakeel Butt Cc: Zi Yan Signed-off-by: Andrew Morton

mm: reimplement folio_is_fsdax()

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

For callers of folio_is_fsdax(), we save a folio->page->folio conversion. Callers of is_fsdax_page() simply move the conversion of page->folio from the implementation of page_pgmap() to is_fsdax_page(). Link: https://lkml.kernel.org/r/20250805172307.1302730-11-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Zi Yan Cc: Shakeel Butt Signed-off-by: Andrew Morton

mm: reimplement folio_is_device_coherent()

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

For callers of folio_is_device_coherent(), we save a folio->page->folio conversion. Callers of is_device_coherent_page() simply move the conversion of page->folio from the implementation of page_pgmap() to is_device_coherent_page(). Link: https://lkml.kernel.org/r/20250805172307.1302730-10-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Zi Yan Cc: Shakeel Butt Signed-off-by: Andrew Morton

mm: reimplement folio_is_device_private()

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

For callers of folio_is_device_private(), we save a folio->page->folio conversion. Callers of is_device_private_page() simply move the conversion of page->folio from the implementation of page_pgmap() to is_device_private_page(). Link: https://lkml.kernel.org/r/20250805172307.1302730-9-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Zi Yan Cc: Shakeel Butt Signed-off-by: Andrew Morton

mm/gup: don't allow FOLL_LONGTERM pinning of FS DAX pages

2025-03-18T05:06:40+00:00

Longterm pinning of FS DAX pages should already be disallowed by various pXX_devmap checks. However a future change will cause these checks to be invalid for FS DAX pages so make folio_is_longterm_pinnable() return false for FS DAX pages. Link: https://lkml.kernel.org/r/250a31876704b79f7c65b159f3c835e547f052df.1740713401.git-series.apopple@nvidia.com Signed-off-by: Alistair Popple Reviewed-by: John Hubbard Reviewed-by: Dan Williams Acked-by: David Hildenbrand Tested-by: Alison Schofield Cc: Alexander Gordeev Cc: Asahi Lina Cc: Balbir Singh 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: Jason Gunthorpe 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

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

memremap.h: correct an error in a comment

2024-02-22T18:24:55+00:00

It tried to send me off to memory_hotplug.h for an enum that is a few lines above... Link: https://lkml.kernel.org/r/dba0f5f01162d6fa16e4da2a9fede7f97080e92d.1707179960.git.john@groves.net Signed-off-by: John Groves Reviewed-by: Dan Williams Cc: Christoph Hellwig Signed-off-by: Andrew Morton

mm/memory_hotplug: introduce MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers

2024-02-22T00:00:01+00:00

Patch series "implement "memmap on memory" feature on s390". This series provides "memmap on memory" support on s390 platform. "memmap on memory" allows struct pages array to be allocated from the hotplugged memory range instead of allocating it from main system memory. s390 currently preallocates struct pages array for all potentially possible memory, which ensures memory onlining always succeeds, but with the cost of significant memory consumption from the available system memory during boottime. In certain extreme configuration, this could lead to ipl failure. "memmap on memory" ensures struct pages array are populated from self contained hotplugged memory range instead of depleting the available system memory and this could eliminate ipl failure on s390 platform. On other platforms, system might go OOM when the physically hotplugged memory depletes the available memory before it is onlined. Hence, "memmap on memory" feature was introduced as described in commit a08a2ae34613 ("mm,memory_hotplug: allocate memmap from the added memory range"). Unlike other architectures, s390 memory blocks are not physically accessible until it is online. To make it physically accessible two new memory notifiers MEM_PREPARE_ONLINE / MEM_FINISH_OFFLINE are added and this notifier lets the hypervisor inform that the memory should be made physically accessible. This allows for "memmap on memory" initialization during memory hotplug onlining phase, which is performed before calling MEM_GOING_ONLINE notifier. Patch 1 introduces MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers to prepare the transition of memory to and from a physically accessible state. New mhp_flag MHP_OFFLINE_INACCESSIBLE is introduced to ensure altmap cannot be written when adding memory - before it is set online. This enhancement is crucial for implementing the "memmap on memory" feature for s390 in a subsequent patch. Patches 2 allocates vmemmap pages from self-contained memory range for s390. It allocates memory map (struct pages array) from the hotplugged memory range, rather than using system memory by passing altmap to vmemmap functions. Patch 3 removes unhandled memory notifier types on s390. Patch 4 implements MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers on s390. MEM_PREPARE_ONLINE memory notifier makes memory block physical accessible via sclp assign command. The notifier ensures self-contained memory maps are accessible and hence enabling the "memmap on memory" on s390. MEM_FINISH_OFFLINE memory notifier shifts the memory block to an inaccessible state via sclp unassign command. Patch 5 finally enables MHP_MEMMAP_ON_MEMORY on s390. This patch (of 5): Introduce MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers to prepare the transition of memory to and from a physically accessible state. This enhancement is crucial for implementing the "memmap on memory" feature for s390 in a subsequent patch. Platforms such as x86 can support physical memory hotplug via ACPI. When there is physical memory hotplug, ACPI event leads to the memory addition with the following callchain: acpi_memory_device_add() -> acpi_memory_enable_device() -> __add_memory() After this, the hotplugged memory is physically accessible, and altmap support prepared, before the "memmap on memory" initialization in memory_block_online() is called. On s390, memory hotplug works in a different way. The available hotplug memory has to be defined upfront in the hypervisor, but it is made physically accessible only when the user sets it online via sysfs, currently in the MEM_GOING_ONLINE notifier. This is too late and "memmap on memory" initialization is performed before calling MEM_GOING_ONLINE notifier. During the memory hotplug addition phase, altmap support is prepared and during the memory onlining phase s390 requires memory to be physically accessible and then subsequently initiate the "memmap on memory" initialization process. The memory provider will handle new MEM_PREPARE_ONLINE / MEM_FINISH_OFFLINE notifications and make the memory accessible. The mhp_flag MHP_OFFLINE_INACCESSIBLE is introduced and is relevant when used along with MHP_MEMMAP_ON_MEMORY, because the altmap cannot be written (e.g., poisoned) when adding memory -- before it is set online. This allows for adding memory with an altmap that is not currently made available by a hypervisor. When onlining that memory, the hypervisor can be instructed to make that memory accessible via the new notifiers and the onlining phase will not require any memory allocations, which is helpful in low-memory situations. All architectures ignore unknown memory notifiers. Therefore, the introduction of these new notifiers does not result in any functional modifications across architectures. Link: https://lkml.kernel.org/r/20240108132747.3238763-1-sumanthk@linux.ibm.com Link: https://lkml.kernel.org/r/20240108132747.3238763-2-sumanthk@linux.ibm.com Signed-off-by: Sumanth Korikkar Suggested-by: Gerald Schaefer Suggested-by: David Hildenbrand Acked-by: David Hildenbrand Cc: Alexander Gordeev Cc: Aneesh Kumar K.V Cc: Anshuman Khandual Cc: Heiko Carstens Cc: Michal Hocko Cc: Oscar Salvador Cc: Vasily Gorbik Signed-off-by: Andrew Morton

mm: use vmem_altmap code without CONFIG_ZONE_DEVICE

2023-12-11T00:51:48+00:00

vmem_altmap_free() and vmem_altmap_offset() could be utlized without CONFIG_ZONE_DEVICE enabled. For example, mm/memory_hotplug.c:__add_pages() relies on that. The altmap is no longer restricted to ZONE_DEVICE handling, but instead depends on CONFIG_SPARSEMEM_VMEMMAP. When CONFIG_SPARSEMEM_VMEMMAP is disabled, these functions are defined as inline stubs, ensuring compatibility with configurations that do not use sparsemem vmemmap. Without it, lkp reported the following: ld: arch/x86/mm/init_64.o: in function `remove_pagetable': init_64.c:(.meminit.text+0xfc7): undefined reference to `vmem_altmap_free' Link: https://lkml.kernel.org/r/20231120145354.308999-4-sumanthk@linux.ibm.com Signed-off-by: Sumanth Korikkar Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202311180545.VeyRXEDq-lkp@intel.com/ Reviewed-by: Gerald Schaefer Acked-by: David Hildenbrand Cc: Alexander Gordeev Cc: Aneesh Kumar K.V Cc: Anshuman Khandual Cc: Heiko Carstens Cc: Michal Hocko Cc: Oscar Salvador Cc: Vasily Gorbik Signed-off-by: Andrew Morton