kernel/git/stable/linux.git/arch/arm/mm/fault-armv.c, branch master

mm: use linear_page_[index, delta]() consistently

2026-08-05T02:19:01+00:00

There are a number of places where we open code what linear_page_index() and linear_page_delta() calculate. Replace this code with the appropriate functions for consistency. No functional change intended. Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-21-2a5aa403d977@kernel.org Signed-off-by: Lorenzo Stoakes Reviewed-by: Thomas Zimmermann [DRM] Acked-by: Kai Huang # for sgx Reviewed-by: Gregory Price Reviewed-by: Pedro Falcato # for mm Reviewed-by: Ackerley Tng [guest_memfd] Reviewed-by: Vlastimil Babka (SUSE) Cc: David Hildenbrand (Arm) Cc: Marek Szyprowski Cc: SJ Park Cc: Liam R. Howlett (Oracle) Cc: Zi Yan Signed-off-by: Andrew Morton

mm/rmap: rename vma_interval_tree_() to mapping_rmap_tree_()

2026-08-05T02:18:58+00:00

The family of vma_interval_tree_() functions manipulate the address_space (which, of course, is generally referred to as 'mapping') reverse mapping, but are named the 'VMA' interval tree. VMAs may be mapped by an anon_vma, an address_space, or both. Therefore calling the mapping interval tree a 'VMA' interval tree is rather confusing. This is also inconsistent with the anon_vma_interval_tree_*() functions which explicitly reference the rmap object to which they pertain. Rename the vma_interval_tree_*() functions to mapping_rmap_tree_*() to correct this. We will rename the anon rmap functions similarly in a subsequent patch. No functional change intended. Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-8-2a5aa403d977@kernel.org Signed-off-by: Lorenzo Stoakes Reviewed-by: Gregory Price Reviewed-by: Vlastimil Babka (SUSE) Reviewed-by: Zi Yan Cc: Ackerley Tng Cc: David Hildenbrand (Arm) Cc: Kai Huang Cc: Marek Szyprowski Cc: Pedro Falcato Cc: SJ Park Cc: Thomas Zimmermann Cc: Liam R. Howlett (Oracle) Signed-off-by: Andrew Morton

mm/rmap: parameterise vma_interval_tree_*() by address_space

2026-08-05T02:18:57+00:00

The file-backed mapping interval tree functions vma_interval_tree_*() accept a raw rb_root_cached pointer to determine the tree in which they are operating. However, in each case, this is always associated with an address_space data type. So simply pass a pointer to that instead to simplify the code, and more clearly differentiate between these operations and those concerning anonymous mappings. While we're here, make the generated interval tree functions static as they do not need to be used externally (any previously existing external users have now been removed). We also rename VMA parameters from 'node' to 'vma' as calling this a node is simply confusing, update the input index types to pgoff_t since they reference page offsets and rename the parameters to pgoff_start and pgoff_last. No functional change intended. Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-6-2a5aa403d977@kernel.org Signed-off-by: Lorenzo Stoakes Reviewed-by: Pedro Falcato Reviewed-by: Gregory Price Reviewed-by: Vlastimil Babka (SUSE) Reviewed-by: Zi Yan Cc: Ackerley Tng Cc: David Hildenbrand (Arm) Cc: Kai Huang Cc: Marek Szyprowski Cc: SJ Park Cc: Thomas Zimmermann Cc: Liam R. Howlett (Oracle) Signed-off-by: Andrew Morton

mm: introduce memdesc_flags_t

2025-09-13T23:55:07+00:00

Patch series "Add and use memdesc_flags_t". At some point struct page will be separated from struct slab and struct folio. This is a step towards that by introducing a type for the 'flags' word of all three structures. This gives us a certain amount of type safety by establishing that some of these unsigned longs are different from other unsigned longs in that they contain things like node ID, section number and zone number in the upper bits. That lets us have functions that can be easily called by anyone who has a slab, folio or page (but not easily by anyone else) to get the node or zone. There's going to be some unusual merge problems with this as some odd bits of the kernel decide they want to print out the flags value or something similar by writing page->flags and now they'll need to write page->flags.f instead. That's most of the churn here. Maybe we should be removing these things from the debug output? This patch (of 11): Wrap the unsigned long flags in a typedef. In upcoming patches, this will provide a strong hint that you can't just pass a random unsigned long to functions which take this as an argument. [willy@infradead.org: s/flags/flags.f/ in several architectures] Link: https://lkml.kernel.org/r/aKMgPRLD-WnkPxYm@casper.infradead.org [nicola.vetrini@gmail.com: mips: fix compilation error] Link: https://lore.kernel.org/lkml/CA+G9fYvkpmqGr6wjBNHY=dRp71PLCoi2341JxOudi60yqaeUdg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20250825214245.1838158-1-nicola.vetrini@gmail.com Link: https://lkml.kernel.org/r/20250805172307.1302730-1-willy@infradead.org Link: https://lkml.kernel.org/r/20250805172307.1302730-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Zi Yan Cc: Shakeel Butt Signed-off-by: Andrew Morton

arm: pgtable: fix NULL pointer dereference issue

2025-03-06T05:36:12+00:00

When update_mmu_cache_range() is called by update_mmu_cache(), the vmf parameter is NULL, which will cause a NULL pointer dereference issue in adjust_pte(): Unable to handle kernel NULL pointer dereference at virtual address 00000030 when read Hardware name: Atmel AT91SAM9 PC is at update_mmu_cache_range+0x1e0/0x278 LR is at pte_offset_map_rw_nolock+0x18/0x2c Call trace: update_mmu_cache_range from remove_migration_pte+0x29c/0x2ec remove_migration_pte from rmap_walk_file+0xcc/0x130 rmap_walk_file from remove_migration_ptes+0x90/0xa4 remove_migration_ptes from migrate_pages_batch+0x6d4/0x858 migrate_pages_batch from migrate_pages+0x188/0x488 migrate_pages from compact_zone+0x56c/0x954 compact_zone from compact_node+0x90/0xf0 compact_node from kcompactd+0x1d4/0x204 kcompactd from kthread+0x120/0x12c kthread from ret_from_fork+0x14/0x38 Exception stack(0xc0d8bfb0 to 0xc0d8bff8) To fix it, do not rely on whether 'ptl' is equal to decide whether to hold the pte lock, but decide it by whether CONFIG_SPLIT_PTE_PTLOCKS is enabled. In addition, if two vmas map to the same PTE page, there is no need to hold the pte lock again, otherwise a deadlock will occur. Just add the need_lock parameter to let adjust_pte() know this information. Link: https://lkml.kernel.org/r/20250217024924.57996-1-zhengqi.arch@bytedance.com Fixes: fc9c45b71f43 ("arm: adjust_pte() use pte_offset_map_rw_nolock()") Signed-off-by: Qi Zheng Reported-by: Ezra Buehler Closes: https://lore.kernel.org/lkml/CAM1KZSmZ2T_riHvay+7cKEFxoPgeVpHkVFTzVVEQ1BO0cLkHEQ@mail.gmail.com/ Acked-by: David Hildenbrand Tested-by: Ezra Buehler Cc: Hugh Dickins Cc: Muchun Song Cc: Qi Zheng Cc: Russel King Cc: Ryan Roberts Cc: Signed-off-by: Andrew Morton

arm: adjust_pte() use pte_offset_map_rw_nolock()

2024-11-06T00:56:27+00:00

In do_adjust_pte(), we may modify the pte entry. The corresponding pmd entry may have been modified concurrently. Therefore, in order to ensure the stability if pmd entry, use pte_offset_map_rw_nolock() to replace pte_offset_map_nolock(), and do pmd_same() check after holding the PTL. All callers of update_mmu_cache_range() hold the vmf->ptl, so we can determined whether split PTE locks is being used by doing the following, just as we do elsewhere in the kernel. ptl != vmf->ptl And then we can delete the do_pte_lock() and do_pte_unlock(). Link: https://lkml.kernel.org/r/0eaf6b69aeb2fe35092a633fed12537efe645303.1727332572.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng Acked-by: David Hildenbrand Reviewed-by: Muchun Song Cc: Hugh Dickins Cc: Matthew Wilcox Cc: Mike Rapoport (Microsoft) Cc: Peter Xu Cc: Ryan Roberts Cc: Vishal Moola (Oracle) Signed-off-by: Andrew Morton

mm: turn USE_SPLIT_PTE_PTLOCKS / USE_SPLIT_PTE_PTLOCKS into Kconfig options

2024-09-02T03:25:51+00:00

Patch series "mm: split PTE/PMD PT table Kconfig cleanups+clarifications". This series is a follow up to the fixes: "[PATCH v1 0/2] mm/hugetlb: fix hugetlb vs. core-mm PT locking" When working on the fixes, I wondered why 8xx is fine (-> never uses split PT locks) and how PT locking even works properly with PMD page table sharing (-> always requires split PMD PT locks). Let's improve the split PT lock detection, make hugetlb properly depend on it and make 8xx bail out if it would ever get enabled by accident. As an alternative to patch #3 we could extend the Kconfig SPLIT_PTE_PTLOCKS option from patch #2 -- but enforcing it closer to the code that actually implements it feels a bit nicer for documentation purposes, and there is no need to actually disable it because it should always be disabled (!SMP). Did a bunch of cross-compilations to make sure that split PTE/PMD PT locks are still getting used where we would expect them. [1] https://lkml.kernel.org/r/20240725183955.2268884-1-david@redhat.com This patch (of 3): Let's clean that up a bit and prepare for depending on CONFIG_SPLIT_PMD_PTLOCKS in other Kconfig options. More cleanups would be reasonable (like the arch-specific "depends on" for CONFIG_SPLIT_PTE_PTLOCKS), but we'll leave that for another day. Link: https://lkml.kernel.org/r/20240726150728.3159964-1-david@redhat.com Link: https://lkml.kernel.org/r/20240726150728.3159964-2-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Mike Rapoport (Microsoft) Reviewed-by: Russell King (Oracle) Reviewed-by: Qi Zheng Cc: Alexander Viro Cc: Borislav Petkov Cc: Boris Ostrovsky Cc: Christian Brauner Cc: Christophe Leroy Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Juergen Gross Cc: Michael Ellerman Cc: Muchun Song Cc: "Naveen N. Rao" Cc: Nicholas Piggin Cc: Oscar Salvador Cc: Peter Xu Cc: Thomas Gleixner Signed-off-by: Andrew Morton

arm: implement the new page table range API

2023-08-24T23:20:20+00:00

Add set_ptes(), update_mmu_cache_range(), flush_dcache_folio() and flush_icache_pages(). Change the PG_dcache_clear flag from being per-page to per-folio which makes __dma_page_dev_to_cpu() a bit more exciting. Also add flush_cache_pages(), even though this isn't used by generic code (yet?) [m.szyprowski@samsung.com: fix potential endless loop in __dma_page_dev_to_cpu()] Link: https://lkml.kernel.org/r/20230809172737.3574190-1-m.szyprowski@samsung.com [willy@infradead.org: fix folio conversion in __dma_page_dev_to_cpu()] Link: https://lkml.kernel.org/r/20230823191852.1556561-1-willy@infradead.org Link: https://lkml.kernel.org/r/20230802151406.3735276-10-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Marek Szyprowski Acked-by: Mike Rapoport (IBM) Reviewed-by: Russell King (Oracle) Signed-off-by: Andrew Morton

arm: adjust_pte() use pte_offset_map_nolock()

2023-08-18T17:12:23+00:00

Instead of pte_lockptr(), use the recently added pte_offset_map_nolock() in adjust_pte(): because it gives the not-locked ptl for precisely that pte, which the caller can then safely lock; whereas pte_lockptr() is not so tightly coupled, because it dereferences the pmd pointer again. Link: https://lkml.kernel.org/r/4d5258bd-ffa0-018-253a-25f2c9b783f7@google.com Signed-off-by: Hugh Dickins Cc: Alexander Gordeev Cc: Alistair Popple Cc: Aneesh Kumar K.V Cc: Anshuman Khandual Cc: Axel Rasmussen Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Christoph Hellwig Cc: Claudio Imbrenda Cc: David Hildenbrand Cc: "David S. Miller" Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Huang, Ying Cc: Ira Weiny Cc: Jann Horn Cc: Jason Gunthorpe Cc: Kirill A. Shutemov Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Mel Gorman Cc: Miaohe Lin Cc: Michael Ellerman Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Minchan Kim Cc: Naoya Horiguchi Cc: Pavel Tatashin Cc: Peter Xu Cc: Peter Zijlstra Cc: Qi Zheng Cc: Ralph Campbell Cc: Russell King Cc: SeongJae Park Cc: Song Liu Cc: Steven Price Cc: Suren Baghdasaryan Cc: Thomas Hellström Cc: Vasily Gorbik Cc: Vishal Moola (Oracle) Cc: Vlastimil Babka Cc: Will Deacon Cc: Yang Shi Cc: Yu Zhao Cc: Zack Rusin Cc: Zi Yan Signed-off-by: Andrew Morton

arm: allow pte_offset_map[_lock]() to fail

2023-06-19T23:19:05+00:00

Patch series "arch: allow pte_offset_map[_lock]() to fail", v2. What is it all about? Some mmap_lock avoidance i.e. latency reduction. Initially just for the case of collapsing shmem or file pages to THPs; but likely to be relied upon later in other contexts e.g. freeing of empty page tables (but that's not work I'm doing). mmap_write_lock avoidance when collapsing to anon THPs? Perhaps, but again that's not work I've done: a quick attempt was not as easy as the shmem/file case. I would much prefer not to have to make these small but wide-ranging changes for such a niche case; but failed to find another way, and have heard that shmem MADV_COLLAPSE's usefulness is being limited by that mmap_write_lock it currently requires. These changes (though of course not these exact patches, and not all of these architectures!) have been in Google's data centre kernel for three years now: we do rely upon them. What are the per-arch changes about? Generally, two things. One: the current mmap locking may not be enough to guard against that tricky transition between pmd entry pointing to page table, and empty pmd entry, and pmd entry pointing to huge page: pte_offset_map() will have to validate the pmd entry for itself, returning NULL if no page table is there. What to do about that varies: often the nearby error handling indicates just to skip it; but in some cases a "goto again" looks appropriate (and if that risks an infinite loop, then there must have been an oops, or pfn 0 mistaken for page table, before). Deeper study of each site might show that 90% of them here in arch code could only fail if there's corruption e.g. a transition to THP would be surprising on an arch without HAVE_ARCH_TRANSPARENT_HUGEPAGE. But given the likely extension to freeing empty page tables, I have not limited this set of changes to THP; and it has been easier, and sets a better example, if each site is given appropriate handling. Two: pte_offset_map() will need to do an rcu_read_lock(), with the corresponding rcu_read_unlock() in pte_unmap(). But most architectures never supported CONFIG_HIGHPTE, so some don't always call pte_unmap() after pte_offset_map(), or have used userspace pte_offset_map() where pte_offset_kernel() is more correct. No problem in the current tree, but a problem once an rcu_read_unlock() will be needed to keep balance. A common special case of that comes in arch/*/mm/hugetlbpage.c, if the architecture supports hugetlb pages down at the lowest PTE level. huge_pte_alloc() uses pte_alloc_map(), but generic hugetlb code does no corresponding pte_unmap(); similarly for huge_pte_offset(). In rare transient cases, not yet made possible, pte_offset_map() and pte_offset_map_lock() may not find a page table: handle appropriately. Link: https://lkml.kernel.org/r/a4963be9-7aa6-350-66d0-2ba843e1af44@google.com Link: https://lkml.kernel.org/r/813429a1-204a-1844-eeae-7fd72826c28@google.com Signed-off-by: Hugh Dickins Cc: Alexander Gordeev Cc: Alexandre Ghiti Cc: Aneesh Kumar K.V Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Chris Zankel Cc: Claudio Imbrenda Cc: David Hildenbrand Cc: "David S. Miller" Cc: Geert Uytterhoeven Cc: Greg Ungerer Cc: Heiko Carstens Cc: Helge Deller Cc: John David Anglin Cc: John Paul Adrian Glaubitz Cc: Kirill A. Shutemov Cc: Matthew Wilcox (Oracle) Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Palmer Dabbelt Cc: Peter Zijlstra Cc: Qi Zheng Cc: Russell King Cc: Suren Baghdasaryan Cc: Thomas Bogendoerfer Cc: Will Deacon Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Thomas Gleixner Signed-off-by: Andrew Morton