* + mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch added to mm-unstable branch
@ 2026-09-16 2:06 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-09-16 2:06 UTC (permalink / raw)
To: mm-commits, ljs, akpm
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
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
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and is updated there most days
------------------------------------------------------
From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Subject: mm: enable MMU_GATHER_RCU_TABLE_FREE for m68k-motorola
Date: Fri, 11 Sep 2026 20:36:56 +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 an irq save/restore 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().
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/20260911-rcu-pagetable-freeing-v3-9-7b8c86103821@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <james.bottomley@HansenPartnership.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Zi Yan <ziy@nvidia.com>
---
arch/m68k/Kconfig | 3
arch/m68k/include/asm/motorola_pgalloc.h | 9 -
arch/m68k/mm/motorola.c | 121 +++++++++++++--------
3 files changed, 86 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 <linux/init.h>
#include <linux/memblock.h>
#include <linux/gfp.h>
+#include <linux/cleanup.h>
#include <asm/setup.h>
#include <linux/uaccess.h>
@@ -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 +142,66 @@ 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_irqsave, &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;
+ unsigned long flags;
+ 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_irqsave(&ptable_lock, flags);
+ 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_irqrestore(&ptable_lock, flags);
+ return add_pointer_table(mm, type);
}
for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += ptable_size(type))
@@ -194,7 +211,10 @@ 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_irqrestore(&ptable_lock, flags);
+ return ret;
}
int free_pointer_table(void *table, int type)
@@ -203,6 +223,9 @@ int free_pointer_table(void *table, int
unsigned long ptable = (unsigned long)table;
unsigned long pt_addr = ptable & PAGE_MASK;
unsigned int mask = 1U << ((ptable - pt_addr)/ptable_size(type));
+ unsigned long flags;
+
+ spin_lock_irqsave(&ptable_lock, flags);
dp = PD_PTABLE(pt_addr);
if (PD_MARKBITS (dp) & mask)
@@ -213,6 +236,8 @@ 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_irqrestore(&ptable_lock, flags);
+
mmu_page_dtor((void *)pt_addr);
pagetable_dtor_free(virt_to_ptdesc((void *)pt_addr));
return 1;
@@ -223,9 +248,21 @@ int free_pointer_table(void *table, int
*/
list_move(dp, &ptable_list[type]);
}
+
+ spin_unlock_irqrestore(&ptable_lock, flags);
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-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-huge_memory-zap-deposited-page-tables-after-an-rcu-grace-period.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-make-userland-page-table-freeing-rcu-safe.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-predicate-setting-mmap_prepare-vma-fields-on-new-vma-alloc.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
^ permalink raw reply [flat|nested] 3+ messages in thread
* + mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch added to mm-unstable branch
@ 2026-09-23 20:01 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-09-23 20:01 UTC (permalink / raw)
To: mm-commits, ljs, akpm
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)" <ljs@kernel.org>
Subject: mm: enable MMU_GATHER_RCU_TABLE_FREE for m68k-motorola
Date: Tue, 22 Sep 2026 16:35:40 +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 an irq save/restore 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().
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/20260922-rcu-pagetable-freeing-v4-9-fe1ad1f1e303@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Acked-by: Lance Yang <lance.yang@linux.dev>
Tested-by: Lance Yang <lance.yang@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Nico Pache <nico.pache@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Guo Ren <guoren@kernel.org>
Cc: Brian Cain <bcain@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Simon Schuster <schuster.simon@siemens-energy.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Rich Felker <dalias@libc.org>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: James Bottomley <james.bottomley@hansenpartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <chleroy@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Qi Zheng <qi.zheng@linux.dev>
---
arch/m68k/Kconfig | 3
arch/m68k/include/asm/motorola_pgalloc.h | 9 -
arch/m68k/mm/motorola.c | 121 +++++++++++++--------
3 files changed, 86 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 <linux/init.h>
#include <linux/memblock.h>
#include <linux/gfp.h>
+#include <linux/cleanup.h>
#include <asm/setup.h>
#include <linux/uaccess.h>
@@ -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 +142,66 @@ 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_irqsave, &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;
+ unsigned long flags;
+ 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_irqsave(&ptable_lock, flags);
+ 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_irqrestore(&ptable_lock, flags);
+ return add_pointer_table(mm, type);
}
for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += ptable_size(type))
@@ -194,7 +211,10 @@ 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_irqrestore(&ptable_lock, flags);
+ return ret;
}
int free_pointer_table(void *table, int type)
@@ -203,6 +223,9 @@ int free_pointer_table(void *table, int
unsigned long ptable = (unsigned long)table;
unsigned long pt_addr = ptable & PAGE_MASK;
unsigned int mask = 1U << ((ptable - pt_addr)/ptable_size(type));
+ unsigned long flags;
+
+ spin_lock_irqsave(&ptable_lock, flags);
dp = PD_PTABLE(pt_addr);
if (PD_MARKBITS (dp) & mask)
@@ -213,6 +236,8 @@ 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_irqrestore(&ptable_lock, flags);
+
mmu_page_dtor((void *)pt_addr);
pagetable_dtor_free(virt_to_ptdesc((void *)pt_addr));
return 1;
@@ -223,9 +248,21 @@ int free_pointer_table(void *table, int
*/
list_move(dp, &ptable_list[type]);
}
+
+ spin_unlock_irqrestore(&ptable_lock, flags);
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-khugepaged-deposit-a-newly-allocated-page-table-on-collapse-fix.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-make-userland-page-table-freeing-rcu-safe.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
^ permalink raw reply [flat|nested] 3+ messages in thread
* + mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch added to mm-unstable branch
@ 2026-09-25 22:28 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-09-25 22:28 UTC (permalink / raw)
To: mm-commits, ljs, akpm
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)" <ljs@kernel.org>
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) <ljs@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Acked-by: Lance Yang <lance.yang@linux.dev>
Tested-by: Lance Yang <lance.yang@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Nico Pache <nico.pache@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Guo Ren <guoren@kernel.org>
Cc: Brian Cain <bcain@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Simon Schuster <schuster.simon@siemens-energy.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Rich Felker <dalias@libc.org>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: James Bottomley <james.bottomley@hansenpartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <chleroy@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Qi Zheng <qi.zheng@linux.dev>
---
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 <linux/init.h>
#include <linux/memblock.h>
#include <linux/gfp.h>
+#include <linux/cleanup.h>
#include <asm/setup.h>
#include <linux/uaccess.h>
@@ -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
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-09-25 22:28 UTC | newest]
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2026-09-23 20:01 + mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch added to mm-unstable branch Andrew Morton
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2026-09-25 22:28 Andrew Morton
2026-09-16 2:06 Andrew Morton
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