From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EC7E15013A5 for ; Fri, 25 Sep 2026 22:28:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790375328; cv=none; b=rOO3t+KLfTwE/RgI4sWUVssrYI0SuPM/tdUje7ogDrsYToUV9cbM7pVoiHKZyXpFC2iADija1ybx6AfU0S9u4ME+JNBm6YkfmldZJkWOVIjc53+svCNoKrpvwbzAJsQZeWmiaEmSu2R4habPdSUhaTOzRS2njQXqu+NZj6nQsEo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790375328; c=relaxed/simple; bh=5dOxOFF6/RTolKGq2Mncf3elMSUCk6E+lEHcV4gEUYI=; h=Date:To:From:Subject:Message-Id; b=FqyRxpCX/9PcWXDkv0nCFlzZ1LY7DSDDShXYdDKIqKgpSwpWHWKTXgiXIEUnTkSoUty3Hy1jjAZYkHkdm5+EzZ8IH6ppFKTqKz+N2AOFQBUCLDAuzMixfSyveH928zK67gAQ6INtonFn/14kFkH8R+9miWIOfsAnPVfCiHYx3j8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=Xbr2eKPZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="Xbr2eKPZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8D7F1F000FF; Fri, 25 Sep 2026 22:28:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1790375325; bh=90cbrPiydkNMAitf87GMab18JQbkd7m+4UVrhx+vm8s=; h=Date:To:From:Subject; b=Xbr2eKPZbczzKpZ6VMAjXOSGq7qqCh2WbACFJFEotpRzzJ2sr7NWXL9SnQyr4xua3 mqkSWVWQpA9y0K4MkSnUTGw71pniQG3zATVplRBrt12yR78CNsb/0VhAqHLTc5NllF BxSdb0bQS7dGgMurja00UPDUSIQzu/qTujY7xUzs= Date: Fri, 25 Sep 2026 15:28:45 -0700 To: mm-commits@vger.kernel.org,ljs@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch added to mm-unstable branch Message-Id: <20260925222845.A8D7F1F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: enable MMU_GATHER_RCU_TABLE_FREE for m68k-motorola has been added to the -mm mm-unstable branch. Its filename is mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: "Lorenzo Stoakes (ARM)" Subject: mm: enable MMU_GATHER_RCU_TABLE_FREE for m68k-motorola Date: Fri, 25 Sep 2026 21:09:44 +0100 sun3 and coldfire are already supported, however motorola requires a little more care. Here, custom table removal logic is required, so CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE is enabled for m68k-motorola. Firstly as part of this change, the page table level must be communicated to the underlying __tlb_remove_table() implementation. Take advantage of the fact that page tables are aligned by more than enough to permit setting TABLE_PTE or TABLE_PMD in the low bits of the pointer, and store this there. Then update __pte_free_tlb() and __pmd_free_tlb() to pass this through, then have __tlb_remove_table() decode this and pass it to free_pointer_table(). The page table freeing is performed via call_rcu(), so free_pointer_table() now will be invoked from softirq context, and as such may be re-entrant. Introduce a spinlock to handle this and hold it over the time a given ptable entry is being referenced in both get_pointer_table() and free_pointer_table(). As softirq is the only asynchronous context in which the lock is taken, it suffices to disable bottom halves while holding it. In order to make things a little easier in this respect, separate out the logic for adding a new ptable entry into add_pointer_table() and only hold the lock during ptable entry insertion in this case. Note that original list_add_tail(new, dp) added new prior to dp, which is ptable_list[type].next, i.e. after ptable_list[type]. The equivalent therefore is list_add(new, &ptable_list[type]), which adds new after ptable_list[type], only without needing to make reference to dp. Note that, as m68k-motorola specifies CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE, it does not enable CONFIG_PT_RECLAIM. This isn't meaningfully impactful. With this applied, all of m68k implements CONFIG_MMU_GATHER_RCU_TABLE_FREE. This forms part of an overall effort to switch every architecture to this mode. Link: https://lore.kernel.org/20260925-rcu-pagetable-freeing-v5-9-31e91065fea4@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Signed-off-by: Andrew Morton Acked-by: Kiryl Shutsemau (Meta) Acked-by: Lance Yang Tested-by: Lance Yang Cc: David Hildenbrand Cc: Zi Yan Cc: Baolin Wang Cc: Liam R. Howlett Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Usama Arif Cc: Guo Ren Cc: Brian Cain Cc: Geert Uytterhoeven Cc: Dinh Nguyen Cc: Simon Schuster Cc: Jonas Bonn Cc: Stefan Kristiansson Cc: Stafford Horne Cc: Rich Felker Cc: John Paul Adrian Glaubitz Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Albert Ou Cc: Alexandre Ghiti Cc: Russell King Cc: Vineet Gupta Cc: Michal Simek Cc: Chris Zankel Cc: Max Filippov Cc: Will Deacon Cc: Aneesh Kumar K.V Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: David S. Miller Cc: Andreas Larsson Cc: Richard Henderson Cc: Matt Turner Cc: Magnus Lindholm Cc: Catalin Marinas Cc: Mark Rutland Cc: Huacai Chen Cc: WANG Xuerui Cc: Thomas Bogendoerfer Cc: James Bottomley Cc: Helge Deller Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Christophe Leroy Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Alexander Gordeev Cc: Christian Borntraeger Cc: Sven Schnelle Cc: Richard Weinberger Cc: Anton Ivanov Cc: Johannes Berg Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Arnd Bergmann Cc: Vlastimil Babka Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: Jason Gunthorpe Cc: John Hubbard Cc: Peter Xu Cc: Yoshinori Sato Cc: Shakeel Butt Cc: Jonathan Corbet Cc: Randy Dunlap Cc: Hugh Dickins Cc: Qi Zheng --- arch/m68k/Kconfig | 3 arch/m68k/include/asm/motorola_pgalloc.h | 9 - arch/m68k/mm/motorola.c | 119 +++++++++++++-------- 3 files changed, 84 insertions(+), 47 deletions(-) --- a/arch/m68k/include/asm/motorola_pgalloc.h~mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola +++ a/arch/m68k/include/asm/motorola_pgalloc.h @@ -17,6 +17,7 @@ enum m68k_table_types { extern void init_pointer_table(void *table, int type); extern void *get_pointer_table(struct mm_struct *mm, int type); extern int free_pointer_table(void *table, int type); +extern void __tlb_remove_table(void *table); /* * Allocate and free page tables. The xxx_kernel() versions are @@ -47,7 +48,7 @@ static inline void pte_free(struct mm_st static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pgtable, unsigned long address) { - free_pointer_table(pgtable, TABLE_PTE); + tlb_remove_table(tlb, (void *)((unsigned long)pgtable | TABLE_PTE)); } @@ -61,10 +62,10 @@ static inline int pmd_free(struct mm_str return free_pointer_table(pmd, TABLE_PMD); } -static inline int __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd, - unsigned long address) +static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd, + unsigned long address) { - return free_pointer_table(pmd, TABLE_PMD); + tlb_remove_table(tlb, (void *)((unsigned long)pmd | TABLE_PMD)); } --- a/arch/m68k/Kconfig~mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola +++ a/arch/m68k/Kconfig @@ -29,6 +29,7 @@ config M68K select HAVE_ARCH_LIBGCC_H select HAVE_ARCH_SECCOMP select HAVE_ARCH_SECCOMP_FILTER + select HAVE_ARCH_TLB_REMOVE_TABLE if MMU_MOTOROLA select HAVE_ASM_MODVERSIONS select HAVE_DEBUG_BUGVERBOSE select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_HAS_NO_UNALIGNED @@ -36,7 +37,7 @@ config M68K select HAVE_MOD_ARCH_SPECIFIC select HAVE_UID16 select MMU_GATHER_NO_RANGE if MMU - select MMU_GATHER_RCU_TABLE_FREE if MMU && (SUN3 || COLDFIRE) + select MMU_GATHER_RCU_TABLE_FREE if MMU select MODULES_USE_ELF_REL select MODULES_USE_ELF_RELA select NO_DMA if !MMU && !COLDFIRE --- a/arch/m68k/mm/motorola.c~mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola +++ a/arch/m68k/mm/motorola.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include @@ -103,6 +104,8 @@ static struct list_head ptable_list[3] = LIST_HEAD_INIT(ptable_list[2]), }; +static DEFINE_SPINLOCK(ptable_lock); + #define PD_PTABLE(ptdesc) ((ptable_desc *)&(virt_to_ptdesc((void *)(ptdesc))->pt_list)) #define PD_PTDESC(ptable) (list_entry(ptable, struct ptdesc, pt_list)) #define PD_MARKBITS(dp) (*(unsigned int *)&PD_PTDESC(dp)->pt_index) @@ -139,52 +142,65 @@ void __init init_pointer_table(void *tab return; } +/* + * For a pointer table for a user process address space, a + * table is taken from a ptdesc allocated for the purpose. Each + * ptdesc can hold 8 pointer tables. The ptdesc is remapped in + * virtual address space to be noncacheable. + */ +static void *add_pointer_table(struct mm_struct *mm, int type) +{ + struct ptdesc *ptdesc; + ptable_desc *new; + void *pt_addr; + + ptdesc = pagetable_alloc(GFP_KERNEL | __GFP_ZERO, 0); + if (!ptdesc) + return NULL; + + pt_addr = ptdesc_address(ptdesc); + + switch (type) { + case TABLE_PTE: + /* + * m68k doesn't have SPLIT_PTE_PTLOCKS for not having + * SMP. + */ + pagetable_pte_ctor(mm, ptdesc); + break; + case TABLE_PMD: + pagetable_pmd_ctor(mm, ptdesc); + break; + case TABLE_PGD: + pagetable_pgd_ctor(ptdesc); + break; + } + + mmu_page_ctor(pt_addr); + + new = PD_PTABLE(pt_addr); + + PD_MARKBITS(new) = ptable_mask(type) - 1; + scoped_guard(spinlock_bh, &ptable_lock) + list_add(new, &ptable_list[type]); + + return (pmd_t *)pt_addr; +} + void *get_pointer_table(struct mm_struct *mm, int type) { - ptable_desc *dp = ptable_list[type].next; - unsigned int mask = list_empty(&ptable_list[type]) ? 0 : PD_MARKBITS(dp); unsigned int tmp, off; + unsigned long mask; + ptable_desc *dp; + void *ret; - /* - * For a pointer table for a user process address space, a - * table is taken from a ptdesc allocated for the purpose. Each - * ptdesc can hold 8 pointer tables. The ptdesc is remapped in - * virtual address space to be noncacheable. - */ - if (mask == 0) { - struct ptdesc *ptdesc; - ptable_desc *new; - void *pt_addr; - - ptdesc = pagetable_alloc(GFP_KERNEL | __GFP_ZERO, 0); - if (!ptdesc) - return NULL; - - pt_addr = ptdesc_address(ptdesc); - - switch (type) { - case TABLE_PTE: - /* - * m68k doesn't have SPLIT_PTE_PTLOCKS for not having - * SMP. - */ - pagetable_pte_ctor(mm, ptdesc); - break; - case TABLE_PMD: - pagetable_pmd_ctor(mm, ptdesc); - break; - case TABLE_PGD: - pagetable_pgd_ctor(ptdesc); - break; - } - - mmu_page_ctor(pt_addr); - - new = PD_PTABLE(pt_addr); - PD_MARKBITS(new) = ptable_mask(type) - 1; - list_add_tail(new, dp); + spin_lock_bh(&ptable_lock); + dp = ptable_list[type].next; + mask = list_empty(&ptable_list[type]) ? 0 : PD_MARKBITS(dp); - return (pmd_t *)pt_addr; + if (mask == 0) { + spin_unlock_bh(&ptable_lock); + return add_pointer_table(mm, type); } for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += ptable_size(type)) @@ -194,7 +210,10 @@ void *get_pointer_table(struct mm_struct /* move to end of list */ list_move_tail(dp, &ptable_list[type]); } - return ptdesc_address(PD_PTDESC(dp)) + off; + + ret = ptdesc_address(PD_PTDESC(dp)) + off; + spin_unlock_bh(&ptable_lock); + return ret; } int free_pointer_table(void *table, int type) @@ -204,6 +223,8 @@ int free_pointer_table(void *table, int unsigned long pt_addr = ptable & PAGE_MASK; unsigned int mask = 1U << ((ptable - pt_addr)/ptable_size(type)); + spin_lock_bh(&ptable_lock); + dp = PD_PTABLE(pt_addr); if (PD_MARKBITS (dp) & mask) panic ("table already free!"); @@ -213,6 +234,8 @@ int free_pointer_table(void *table, int if (PD_MARKBITS(dp) == ptable_mask(type)) { /* all tables in ptdesc are free, free ptdesc */ list_del(dp); + spin_unlock_bh(&ptable_lock); + mmu_page_dtor((void *)pt_addr); pagetable_dtor_free(virt_to_ptdesc((void *)pt_addr)); return 1; @@ -223,9 +246,21 @@ int free_pointer_table(void *table, int */ list_move(dp, &ptable_list[type]); } + + spin_unlock_bh(&ptable_lock); return 0; } +void __tlb_remove_table(void *table) +{ + /* The bottom 2 bits are used to encode page table type. */ + const unsigned long encoded = (unsigned long)table; + void *addr = (void *)(encoded & ~3UL); + const int type = encoded & 3; + + free_pointer_table(addr, type); +} + /* size of memory already mapped in head.S */ extern __initdata unsigned long m68k_init_mapped_size; _ Patches currently in -mm which might be from ljs@kernel.org are mm-vma-predicate-setting-mmap_prepare-vma-fields-on-new-vma-alloc.patch mm-mremap-fix-locked_vm-leak-from-mremap_dontunmap-self-merge.patch mm-mremap-fix-locked_vm-leak-by-splitting-vma-for-mremap_dontunmap.patch mm-vmpressure-remove-window-size-todo.patch tools-testing-selftests-mm-add-missing-gitignore-entries.patch mm-move-drivers-char-memc-to-mm-char-memc.patch mm-implement-file_is_dev_zero-to-uniquely-identify-dev-zero.patch mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch mm-madvise-swap-in-cowd-map_private-file-mappings-on-madv_willneed.patch mm-khugepaged-deposit-a-newly-allocated-page-table-on-collapse.patch mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-riscv.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-arm.patch mm-enable-mmu_gather_rcu_table_free-for-arc-microblaze-xtensa.patch mm-enable-mmu_gather_rcu_table_free-for-sparc64.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-coldfire.patch mm-enable-mmu_gather_rcu_table_free-for-sh-x2.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch mm-enable-mmu_gather_rcu_table_free-for-sparc32.patch mm-userland-pgtable-freeing-is-rcu-safe-now-remove-leftover-bits.patch mm-change-the-contract-for-free_pgtables-update-docs.patch mm-vma-fix-mmap_prepare-file-handling-remove-file_doesnt_need_get.patch mm-vma-introduce-and-use-vma_can_merge.patch mm-consistently-validate-vma-state-after-mmap-hooks.patch mm-vma-ensure-mmap_prepare-doesnt-set-actions-on-a-mergeable-vma.patch mm-make-map_kernel_pages_-internal-and-unexported.patch mm-vma-tidy-up-map-kernel-pages-enum-values.patch mm-add-mmap-action-for-discontiguous-kernel-page-mapping.patch docs-filesystems-update-mmap_prepare-docs-for-discontig-kernel-pgs.patch drivers-usb-mon-update-to-use-mmap_prepare-map-kernel-pages.patch infiniband-update-hfi1-to-use-remap_vmalloc_range.patch selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch alsa-pcm-use-vm_insert_page-to-map-pcm-status-page.patch bpf-arena-mark-arena_map_mmap-mappings-vm_mixedmap.patch mm-vma-add-vma_is_kernel_owned-predicates.patch mm-vma-only-allow-mmap-to-clear-vma_maywrite_bit-if-kernel-owned.patch mm-vma-add-and-use-vma__is_fixed_mapping.patch scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch fbdev-defio-assert-fbinfo_virtfb-drop-vm_io-add-vm_mixedmap.patch hsi-cmt_speech-convert-mmap-hook-to-mmap_prepare-refactor.patch mm-gup-error-out-early-on-vma_mayread_bit-vmas.patch uprobes-remove-vm_io-set-vm_mixedmap-for-mapped-kernel-pages.patch mm-mlock-clear-vma_locked_mask-over-mmap-callback.patch mm-mlock-eliminate-weird-vma_io_bit-abuse-and-simplify.patch mm-vma-enforce-that-only-kernel-owned-mappings-may-set-vma_io_bit.patch mm-remove-vma_io_bit-check-in-vma_is_kernel_owned.patch mm-remove-hugetlb_inlineh.patch mm-rename-is_vm_hugetlb_page-to-vma_is_hugetlb.patch mm-drop-some-redundant-checks-around-hugetlb-vmas.patch mm-madvise-update-is_valid_guard_vma-to-use-vma_can_merge.patch mm-vma-introduce-vma_is_persistent.patch mm-uffd-use-predicates-for-userfaultfd-checks.patch mm-madvise-use-predicates-for-madvise-madv_dofork.patch mm-eliminate-vma_special_flags-usage-when-hugetlb-explicitly-tested.patch mm-eliminate-vma_special_flags-check-in-lru_gen_look_around.patch mm-avoid-use-of-vma_special_flags-in-migrate_vma_setup.patch mm-eliminate-vm_special-vma_special_flags.patch fuse-dax-do-not-set-vm_mixedmap.patch mm-huge_memory-remove-vma_is_special_huge.patch mm-vma-introduce-and-use-vma_can_gup.patch mm-vma-const-ify-vma_assert_stabilised-and-associated-functions.patch mm-implement-and-use-vma_has_anon_rmap-silence-kcsan.patch mm-update-comments-to-refer-to-anon-rmap-rather-than-anon_vma.patch