kernel/arch/m68k/mm, branch 0x221E-v0.0.1-v6.19

m68k: mm: Convert pointer table macros to use ptdescs

2025-06-30T19:20:17Z

Motorola uses its pointer tables for page tables, so its macros should be using struct ptdesc, not struct page. This removes a user of page->lru. Signed-off-by: "Vishal Moola (Oracle)" Reviewed-by: Geert Uytterhoeven Link: https://lore.kernel.org/20250611001255.527952-5-vishal.moola@gmail.com Signed-off-by: Geert Uytterhoeven

m68k: mm: Convert init_pointer_table() to use ptdescs

2025-06-30T19:20:17Z

Motorola uses init_pointer_table() for page tables, so it should be using struct ptdesc, not struct page. This helps us prepare to allocate ptdescs as their own memory descriptor, and prepares to remove a user of page->lru. Signed-off-by: "Vishal Moola (Oracle)" Reviewed-by: Geert Uytterhoeven Link: https://lore.kernel.org/20250611001255.527952-4-vishal.moola@gmail.com Signed-off-by: Geert Uytterhoeven

m68k: mm: Convert free_pointer_table() to use ptdescs

2025-06-30T19:20:17Z

Motorola uses free_pointer_table() for page tables, so it should be using struct ptdesc, not struct page. This helps us prepare to allocate ptdescs as their own memory descriptor, and prepares to remove a user of page->lru. Signed-off-by: "Vishal Moola (Oracle)" Reviewed-by: Geert Uytterhoeven Link: https://lore.kernel.org/20250611001255.527952-3-vishal.moola@gmail.com Signed-off-by: Geert Uytterhoeven

m68k: mm: Convert get_pointer_table() to use ptdescs

2025-06-30T19:20:17Z

Motorola uses get_pointer_table() for page tables, so it should be using struct ptdesc, not struct page. This helps us prepare to allocate ptdescs as their own memory descriptor, and prepares to remove a user of page->lru. Signed-off-by: "Vishal Moola (Oracle)" Reviewed-by: Geert Uytterhoeven Link: https://lore.kernel.org/20250611001255.527952-2-vishal.moola@gmail.com Signed-off-by: Geert Uytterhoeven

m68k: remove use of page->index

2025-06-01T05:46:06Z

Switch to using struct ptdesc to store the markbits which will allow us to remove index from struct page. Link: https://lkml.kernel.org/r/20250516151332.3705351-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Geert Uytterhoeven Signed-off-by: Andrew Morton

mm: pass mm down to pagetable_{pte,pmd}_ctor

2025-05-12T00:48:21Z

Patch series "Always call constructor for kernel page tables", v2. There has been much confusion around exactly when page table constructors/destructors (pagetable_*_[cd]tor) are supposed to be called. They were initially introduced for user PTEs only (to support split page table locks), then at the PMD level for the same purpose. Accounting was added later on, starting at the PTE level and then moving to higher levels (PMD, PUD). Finally, with my earlier series "Account page tables at all levels" [1], the ctor/dtor is run for all levels, all the way to PGD. I thought this was the end of the story, and it hopefully is for user pgtables, but I was wrong for what concerns kernel pgtables. The current situation there makes very little sense: * At the PTE level, the ctor/dtor is not called (at least in the generic implementation). Specific helpers are used for kernel pgtables at this level (pte_{alloc,free}_kernel()) and those have never called the ctor/dtor, most likely because they were initially irrelevant in the kernel case. * At all other levels, the ctor/dtor is normally called. This is potentially wasteful at the PMD level (more on that later). This series aims to ensure that the ctor/dtor is always called for kernel pgtables, as it already is for user pgtables. Besides consistency, the main motivation is to guarantee that ctor/dtor hooks are systematically called; this makes it possible to insert hooks to protect page tables [2], for instance. There is however an extra challenge: split locks are not used for kernel pgtables, and it would therefore be wasteful to initialise them (ptlock_init()). It is worth clarifying exactly when split locks are used. They clearly are for user pgtables, but as illustrated in commit 61444cde9170 ("ARM: 8591/1: mm: use fully constructed struct pages for EFI pgd allocations"), they also are for special page tables like efi_mm. The one case where split locks are definitely unused is pgtables owned by init_mm; this is consistent with the behaviour of apply_to_pte_range(). The approach chosen in this series is therefore to pass the mm associated to the pgtables being constructed to pagetable_{pte,pmd}_ctor() (patch 1), and skip ptlock_init() if mm == &init_mm (patch 3 and 7). This makes it possible to call the PTE ctor/dtor from pte_{alloc,free}_kernel() without unintended consequences (patch 3). As a result the accounting functions are now called at all levels for kernel pgtables, and split locks are never initialised. In configurations where ptlocks are dynamically allocated (32-bit, PREEMPT_RT, etc.) and ARCH_ENABLE_SPLIT_PMD_PTLOCK is selected, this series results in the removal of a kmem_cache allocation for every kernel PMD. Additionally, for certain architectures that do not use such as s390, the same optimisation occurs at the PTE level. === Things get more complicated when it comes to special pgtable allocators (patch 8-12). All architectures need such allocators to create initial kernel pgtables; we are not concerned with those as the ctor cannot be called so early in the boot sequence. However, those allocators may also be used later in the boot sequence or during normal operations. There are two main use-cases: 1. Mapping EFI memory: efi_mm (arm, arm64, riscv) 2. arch_add_memory(): init_mm The ctor is already explicitly run (at the PTE/PMD level) in the first case, as required for pgtables that are not associated with init_mm. However the same allocators may also be used for the second use-case (or others), and this is where it gets messy. Patch 1 calls the ctor with NULL as mm in those situations, as the actual mm isn't available. Practically this means that ptlocks will be unconditionally initialised. This is fine on arm - create_mapping_late() is only used for the EFI mapping. On arm64, __create_pgd_mapping() is also used by arch_add_memory(); patch 8/9/11 ensure that ctors are called at all levels with the appropriate mm. The situation is similar on riscv, but propagating the mm down to the ctor would require significant refactoring. Since they are already called unconditionally, this series leaves riscv no worse off - patch 10 adds comments to clarify the situation. From a cursory look at other architectures implementing arch_add_memory(), s390 and x86 may also need a similar treatment to add constructor calls. This is to be taken care of in a future version or as a follow-up. === The complications in those special pgtable allocators beg the question: does it really make sense to treat efi_mm and init_mm differently in e.g. apply_to_pte_range()? Maybe what we really need is a way to tell if an mm corresponds to user memory or not, and never use split locks for non-user mm's. Feedback and suggestions welcome! This patch (of 12): In preparation for calling constructors for all kernel page tables while eliding unnecessary ptlock initialisation, let's pass down the associated mm to the PTE/PMD level ctors. (These are the two levels where ptlocks are used.) In most cases the mm is already around at the point of calling the ctor so we simply pass it down. This is however not the case for special page table allocators: * arch/arm/mm/mmu.c * arch/arm64/mm/mmu.c * arch/riscv/mm/init.c In those cases, the page tables being allocated are either for standard kernel memory (init_mm) or special page directories, which may not be associated to any mm. For now let's pass NULL as mm; this will be refined where possible in future patches. No functional change in this patch. Link: https://lore.kernel.org/linux-mm/20250103184415.2744423-1-kevin.brodsky@arm.com/ [1] Link: https://lore.kernel.org/linux-hardening/20250203101839.1223008-1-kevin.brodsky@arm.com/ [2] Link: https://lkml.kernel.org/r/20250408095222.860601-1-kevin.brodsky@arm.com Link: https://lkml.kernel.org/r/20250408095222.860601-2-kevin.brodsky@arm.com Signed-off-by: Kevin Brodsky Reviewed-by: Alexander Gordeev [s390] Cc: Albert Ou Cc: Andreas Larsson Cc: Catalin Marinas Cc: David S. Miller Cc: Geert Uytterhoeven Cc: Kevin Brodsky Cc: Linus Waleij Cc: Madhavan Srinivasan Cc: Mark Rutland Cc: Matthew Wilcox (Oracle) Cc: Michael Ellerman Cc: Mike Rapoport Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Qi Zheng Cc: Ryan Roberts Cc: Will Deacon Cc: Yang Shi Cc: Cc: Dave Hansen Signed-off-by: Andrew Morton

arch, mm: make releasing of memory to page allocator more explicit

2025-03-18T05:06:53Z

The point where the memory is released from memblock to the buddy allocator is hidden inside arch-specific mem_init()s and the call to memblock_free_all() is needlessly duplicated in every artiste cure and after introduction of arch_mm_preinit() hook, mem_init() implementation on many architecture only contains the call to memblock_free_all(). Pull memblock_free_all() call into mm_core_init() and drop mem_init() on relevant architectures to make it more explicit where the free memory is released from memblock to the buddy allocator and to reduce code duplication in architecture specific code. Link: https://lkml.kernel.org/r/20250313135003.836600-14-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) Acked-by: Dave Hansen [x86] Acked-by: Geert Uytterhoeven [m68k] Tested-by: Mark Brown Cc: Alexander Gordeev Cc: Andreas Larsson Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Arnd Bergmann Cc: Borislav Betkov Cc: Catalin Marinas Cc: David S. Miller Cc: Dinh Nguyen Cc: Gerald Schaefer Cc: Guo Ren (csky) Cc: Heiko Carstens Cc: Helge Deller Cc: Huacai Chen Cc: Ingo Molnar Cc: Jiaxun Yang Cc: Johannes Berg Cc: John Paul Adrian Glaubitz Cc: Madhavan Srinivasan Cc: Matt Turner Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Palmer Dabbelt Cc: Richard Weinberger Cc: Russel King Cc: Stafford Horne Cc: Thomas Bogendoerfer Cc: Thomas Gleinxer Cc: Vasily Gorbik Cc: Vineet Gupta Cc: Will Deacon Signed-off-by: Andrew Morton

mm/memblock: add memblock_alloc_or_panic interface

2025-01-26T04:22:38Z

Before SLUB initialization, various subsystems used memblock_alloc to allocate memory. In most cases, when memory allocation fails, an immediate panic is required. To simplify this behavior and reduce repetitive checks, introduce `memblock_alloc_or_panic`. This function ensures that memory allocation failures result in a panic automatically, improving code readability and consistency across subsystems that require this behavior. [guoweikang.kernel@gmail.com: arch/s390: save_area_alloc default failure behavior changed to panic] Link: https://lkml.kernel.org/r/20250109033136.2845676-1-guoweikang.kernel@gmail.com Link: https://lore.kernel.org/lkml/Z2fknmnNtiZbCc7x@kernel.org/ Link: https://lkml.kernel.org/r/20250102072528.650926-1-guoweikang.kernel@gmail.com Signed-off-by: Guo Weikang Acked-by: Geert Uytterhoeven [m68k] Reviewed-by: Alexander Gordeev [s390] Acked-by: Mike Rapoport (Microsoft) Cc: Alexander Gordeev Signed-off-by: Andrew Morton

mm: introduce ctor/dtor at PGD level

2025-01-26T04:22:24Z

Following on from the introduction of P4D-level ctor/dtor, let's finish the job and introduce ctor/dtor at PGD level. The incurred improvement in page accounting is minimal - the main motivation is to create a single, generic place where construction/destruction hooks can be added for all page table pages. This patch should cover all architectures and all configurations where PGDs are one or more regular pages. This excludes any configuration where PGDs are allocated from a kmem_cache object. Link: https://lkml.kernel.org/r/20250103184415.2744423-7-kevin.brodsky@arm.com Signed-off-by: Kevin Brodsky Acked-by: Dave Hansen Acked-by: Qi Zheng Cc: Andy Lutomirski Cc: Catalin Marinas Cc: Ingo Molnar Cc: Linus Walleij Cc: Matthew Wilcox (Oracle) Cc: Mike Rapoport (Microsoft) Cc: Peter Zijlstra Cc: Ryan Roberts Cc: Thomas Gleixner Cc: Will Deacon Signed-off-by: Andrew Morton

m68k: mm: add calls to pagetable_pmd_[cd]tor

2025-01-26T04:22:24Z

get_pointer_table() and free_pointer_table() already special-case TABLE_PTE to call pagetable_pte_[cd]tor. Let's do the same at PMD level to improve accounting further. TABLE_PGD and TABLE_PMD are currently defined to the same value, so we first need to separate them. That also implies separating ptable_list for PMD/PGD levels. Link: https://lkml.kernel.org/r/20250103184415.2744423-4-kevin.brodsky@arm.com Signed-off-by: Kevin Brodsky Acked-by: Dave Hansen Acked-by: Qi Zheng Cc: Andy Lutomirski Cc: Catalin Marinas Cc: Ingo Molnar Cc: Linus Walleij Cc: Matthew Wilcox (Oracle) Cc: Mike Rapoport (Microsoft) Cc: Peter Zijlstra Cc: Ryan Roberts Cc: Thomas Gleixner Cc: Will Deacon Signed-off-by: Andrew Morton