The patch titled
Subject: mm/vmemmap: improve vmemmap_can_optimize and allow architectures to override
has been added to the -mm mm-unstable branch. Its filename is
mm-vmemmap-improve-vmemmap_can_optimize-and-allow-architectures-to-override.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmemmap-improve-vmemmap_can_optimize-and-allow-architectures-to-override.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: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>
Subject: mm/vmemmap: improve vmemmap_can_optimize and allow architectures to override
Date: Tue, 25 Jul 2023 00:37:49 +0530
dax vmemmap optimization requires a minimum of 2 PAGE_SIZE area within
vmemmap such that tail page mapping can point to the second PAGE_SIZE
area. Enforce that in vmemmap_can_optimize() function.
Architectures like powerpc also want to enable vmemmap optimization
conditionally (only with radix MMU translation). Hence allow architecture
override.
Link: https://lkml.kernel.org/r/20230724190759.483013-4-aneesh.kumar@xxxxxxxxxxxxx
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Joao Martins <joao.m.martins@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 27 +++++++++++++++++++++++----
mm/mm_init.c | 2 +-
2 files changed, 24 insertions(+), 5 deletions(-)
--- a/include/linux/mm.h~mm-vmemmap-improve-vmemmap_can_optimize-and-allow-architectures-to-override
+++ a/include/linux/mm.h
@@ -3665,13 +3665,32 @@ void vmemmap_free(unsigned long start, u
struct vmem_altmap *altmap);
#endif
+#define VMEMMAP_RESERVE_NR 2
#ifdef CONFIG_ARCH_WANT_OPTIMIZE_VMEMMAP
-static inline bool vmemmap_can_optimize(struct vmem_altmap *altmap,
- struct dev_pagemap *pgmap)
+static inline bool __vmemmap_can_optimize(struct vmem_altmap *altmap,
+ struct dev_pagemap *pgmap)
{
- return is_power_of_2(sizeof(struct page)) &&
- pgmap && (pgmap_vmemmap_nr(pgmap) > 1) && !altmap;
+ unsigned long nr_pages;
+ unsigned long nr_vmemmap_pages;
+
+ if (!pgmap || !is_power_of_2(sizeof(struct page)))
+ return false;
+
+ nr_pages = pgmap_vmemmap_nr(pgmap);
+ nr_vmemmap_pages = ((nr_pages * sizeof(struct page)) >> PAGE_SHIFT);
+ /*
+ * For vmemmap optimization with DAX we need minimum 2 vmemmap
+ * pages. See layout diagram in Documentation/mm/vmemmap_dedup.rst
+ */
+ return !altmap && (nr_vmemmap_pages > VMEMMAP_RESERVE_NR);
}
+/*
+ * If we don't have an architecture override, use the generic rule
+ */
+#ifndef vmemmap_can_optimize
+#define vmemmap_can_optimize __vmemmap_can_optimize
+#endif
+
#else
static inline bool vmemmap_can_optimize(struct vmem_altmap *altmap,
struct dev_pagemap *pgmap)
--- a/mm/mm_init.c~mm-vmemmap-improve-vmemmap_can_optimize-and-allow-architectures-to-override
+++ a/mm/mm_init.c
@@ -1020,7 +1020,7 @@ static inline unsigned long compound_nr_
if (!vmemmap_can_optimize(altmap, pgmap))
return pgmap_vmemmap_nr(pgmap);
- return 2 * (PAGE_SIZE / sizeof(struct page));
+ return VMEMMAP_RESERVE_NR * (PAGE_SIZE / sizeof(struct page));
}
static void __ref memmap_init_compound(struct page *head,
_
Patches currently in -mm which might be from aneesh.kumar@xxxxxxxxxxxxx are
mm-hugepage-pud-allow-arch-specific-helper-function-to-check-huge-page-pud-support.patch
mm-change-pudp_huge_get_and_clear_full-take-vm_area_struct-as-arg.patch
mm-vmemmap-improve-vmemmap_can_optimize-and-allow-architectures-to-override.patch
mm-vmemmap-allow-architectures-to-override-how-vmemmap-optimization-works.patch
mm-add-pud_same-similar-to-__have_arch_p4d_same.patch
mm-huge-pud-use-transparent-huge-pud-helpers-only-with-config_transparent_hugepage.patch
mm-vmemmap-optimization-split-hugetlb-and-devdax-vmemmap-optimization.patch
powerpc-mm-trace-convert-trace-event-to-trace-event-class.patch
powerpc-book3s64-mm-enable-transparent-pud-hugepage.patch
powerpc-book3s64-vmemmap-switch-radix-to-use-a-different-vmemmap-handling-function.patch
powerpc-book3s64-radix-add-support-for-vmemmap-optimization-for-radix.patch
powerpc-book3s64-radix-remove-mmu_vmemmap_psize.patch
powerpc-book3s64-radix-add-debug-message-to-give-more-details-of-vmemmap-allocation.patch
