The patch titled
Subject: arm64/mm: implement new [get_and_]clear_full_ptes() batch APIs
has been added to the -mm mm-unstable branch. Its filename is
arm64-mm-implement-new-clear_full_ptes-batch-apis.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/arm64-mm-implement-new-clear_full_ptes-batch-apis.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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------------------------------------------------------
From: Ryan Roberts <ryan.roberts@xxxxxxx>
Subject: arm64/mm: implement new [get_and_]clear_full_ptes() batch APIs
Date: Thu, 15 Feb 2024 10:32:01 +0000
Optimize the contpte implementation to fix some of the
exit/munmap/dontneed performance regression introduced by the initial
contpte commit. Subsequent patches will solve it entirely.
During exit(), munmap() or madvise(MADV_DONTNEED), mappings must be
cleared. Previously this was done 1 PTE at a time. But the core-mm
supports batched clear via the new [get_and_]clear_full_ptes() APIs. So
let's implement those APIs and for fully covered contpte mappings, we no
longer need to unfold the contpte. This significantly reduces unfolding
operations, reducing the number of tlbis that must be issued.
Link: https://lkml.kernel.org/r/20240215103205.2607016-15-ryan.roberts@xxxxxxx
Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Tested-by: John Hubbard <jhubbard@xxxxxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Barry Song <21cnbao@xxxxxxxxx>
Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/pgtable.h | 67 +++++++++++++++++++++++++++++
arch/arm64/mm/contpte.c | 17 +++++++
2 files changed, 84 insertions(+)
--- a/arch/arm64/include/asm/pgtable.h~arm64-mm-implement-new-clear_full_ptes-batch-apis
+++ a/arch/arm64/include/asm/pgtable.h
@@ -965,6 +965,37 @@ static inline pte_t __ptep_get_and_clear
return pte;
}
+static inline void __clear_full_ptes(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep, unsigned int nr, int full)
+{
+ for (;;) {
+ __ptep_get_and_clear(mm, addr, ptep);
+ if (--nr == 0)
+ break;
+ ptep++;
+ addr += PAGE_SIZE;
+ }
+}
+
+static inline pte_t __get_and_clear_full_ptes(struct mm_struct *mm,
+ unsigned long addr, pte_t *ptep,
+ unsigned int nr, int full)
+{
+ pte_t pte, tmp_pte;
+
+ pte = __ptep_get_and_clear(mm, addr, ptep);
+ while (--nr) {
+ ptep++;
+ addr += PAGE_SIZE;
+ tmp_pte = __ptep_get_and_clear(mm, addr, ptep);
+ if (pte_dirty(tmp_pte))
+ pte = pte_mkdirty(pte);
+ if (pte_young(tmp_pte))
+ pte = pte_mkyoung(pte);
+ }
+ return pte;
+}
+
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR
static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
@@ -1160,6 +1191,11 @@ extern pte_t contpte_ptep_get(pte_t *pte
extern pte_t contpte_ptep_get_lockless(pte_t *orig_ptep);
extern void contpte_set_ptes(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte, unsigned int nr);
+extern void contpte_clear_full_ptes(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep, unsigned int nr, int full);
+extern pte_t contpte_get_and_clear_full_ptes(struct mm_struct *mm,
+ unsigned long addr, pte_t *ptep,
+ unsigned int nr, int full);
extern int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep);
extern int contpte_ptep_clear_flush_young(struct vm_area_struct *vma,
@@ -1253,6 +1289,35 @@ static inline void pte_clear(struct mm_s
__pte_clear(mm, addr, ptep);
}
+#define clear_full_ptes clear_full_ptes
+static inline void clear_full_ptes(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep, unsigned int nr, int full)
+{
+ if (likely(nr == 1)) {
+ contpte_try_unfold(mm, addr, ptep, __ptep_get(ptep));
+ __clear_full_ptes(mm, addr, ptep, nr, full);
+ } else {
+ contpte_clear_full_ptes(mm, addr, ptep, nr, full);
+ }
+}
+
+#define get_and_clear_full_ptes get_and_clear_full_ptes
+static inline pte_t get_and_clear_full_ptes(struct mm_struct *mm,
+ unsigned long addr, pte_t *ptep,
+ unsigned int nr, int full)
+{
+ pte_t pte;
+
+ if (likely(nr == 1)) {
+ contpte_try_unfold(mm, addr, ptep, __ptep_get(ptep));
+ pte = __get_and_clear_full_ptes(mm, addr, ptep, nr, full);
+ } else {
+ pte = contpte_get_and_clear_full_ptes(mm, addr, ptep, nr, full);
+ }
+
+ return pte;
+}
+
#define __HAVE_ARCH_PTEP_GET_AND_CLEAR
static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
@@ -1337,6 +1402,8 @@ static inline int ptep_set_access_flags(
#define set_pte __set_pte
#define set_ptes __set_ptes
#define pte_clear __pte_clear
+#define clear_full_ptes __clear_full_ptes
+#define get_and_clear_full_ptes __get_and_clear_full_ptes
#define __HAVE_ARCH_PTEP_GET_AND_CLEAR
#define ptep_get_and_clear __ptep_get_and_clear
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
--- a/arch/arm64/mm/contpte.c~arm64-mm-implement-new-clear_full_ptes-batch-apis
+++ a/arch/arm64/mm/contpte.c
@@ -212,6 +212,23 @@ void contpte_set_ptes(struct mm_struct *
}
EXPORT_SYMBOL(contpte_set_ptes);
+void contpte_clear_full_ptes(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep, unsigned int nr, int full)
+{
+ contpte_try_unfold_partial(mm, addr, ptep, nr);
+ __clear_full_ptes(mm, addr, ptep, nr, full);
+}
+EXPORT_SYMBOL(contpte_clear_full_ptes);
+
+pte_t contpte_get_and_clear_full_ptes(struct mm_struct *mm,
+ unsigned long addr, pte_t *ptep,
+ unsigned int nr, int full)
+{
+ contpte_try_unfold_partial(mm, addr, ptep, nr);
+ return __get_and_clear_full_ptes(mm, addr, ptep, nr, full);
+}
+EXPORT_SYMBOL(contpte_get_and_clear_full_ptes);
+
int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep)
{
_
Patches currently in -mm which might be from ryan.roberts@xxxxxxx are
tools-mm-add-thpmaps-script-to-dump-thp-usage-info.patch
arm64-mm-make-set_ptes-robust-when-oas-cross-48-bit-boundary.patch
mm-clarify-the-spec-for-set_ptes.patch
mm-thp-batch-collapse-pmd-with-set_ptes.patch
mm-introduce-pte_advance_pfn-and-use-for-pte_next_pfn.patch
arm64-mm-convert-pte_next_pfn-to-pte_advance_pfn.patch
x86-mm-convert-pte_next_pfn-to-pte_advance_pfn.patch
mm-tidy-up-pte_next_pfn-definition.patch
arm64-mm-convert-read_onceptep-to-ptep_getptep.patch
arm64-mm-convert-set_pte_at-to-set_ptes-1.patch
arm64-mm-convert-ptep_clear-to-ptep_get_and_clear.patch
arm64-mm-new-ptep-layer-to-manage-contig-bit.patch
arm64-mm-split-__flush_tlb_range-to-elide-trailing-dsb.patch
arm64-mm-wire-up-pte_cont-for-user-mappings.patch
arm64-mm-implement-new-wrprotect_ptes-batch-api.patch
arm64-mm-implement-new-clear_full_ptes-batch-apis.patch
mm-add-pte_batch_hint-to-reduce-scanning-in-folio_pte_batch.patch
arm64-mm-implement-pte_batch_hint.patch
arm64-mm-__always_inline-to-improve-fork-perf.patch
arm64-mm-automatically-fold-contpte-mappings.patch
