The patch titled
Subject: mm/arch: provide pud_pfn() fallback
has been added to the -mm mm-unstable branch. Its filename is
mm-arch-provide-pud_pfn-fallback.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-arch-provide-pud_pfn-fallback.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: Peter Xu <peterx@xxxxxxxxxx>
Subject: mm/arch: provide pud_pfn() fallback
Date: Wed, 27 Mar 2024 11:23:24 -0400
The comment in the code explains the reasons. We took a different
approach comparing to pmd_pfn() by providing a fallback function.
Another option is to provide some lower level config options (compare to
HUGETLB_PAGE or THP) to identify which layer an arch can support for such
huge mappings. However that can be an overkill.
Link: https://lkml.kernel.org/r/20240327152332.950956-6-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Andrew Jones <andrew.jones@xxxxxxxxx>
Cc: Aneesh Kumar K.V (IBM) <aneesh.kumar@xxxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: James Houghton <jthoughton@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/riscv/include/asm/pgtable.h | 1 +
arch/s390/include/asm/pgtable.h | 1 +
arch/sparc/include/asm/pgtable_64.h | 1 +
arch/x86/include/asm/pgtable.h | 1 +
include/linux/pgtable.h | 10 ++++++++++
5 files changed, 14 insertions(+)
--- a/arch/riscv/include/asm/pgtable.h~mm-arch-provide-pud_pfn-fallback
+++ a/arch/riscv/include/asm/pgtable.h
@@ -642,6 +642,7 @@ static inline unsigned long pmd_pfn(pmd_
#define __pud_to_phys(pud) (__page_val_to_pfn(pud_val(pud)) << PAGE_SHIFT)
+#define pud_pfn pud_pfn
static inline unsigned long pud_pfn(pud_t pud)
{
return ((__pud_to_phys(pud) & PUD_MASK) >> PAGE_SHIFT);
--- a/arch/s390/include/asm/pgtable.h~mm-arch-provide-pud_pfn-fallback
+++ a/arch/s390/include/asm/pgtable.h
@@ -1414,6 +1414,7 @@ static inline unsigned long pud_deref(pu
return (unsigned long)__va(pud_val(pud) & origin_mask);
}
+#define pud_pfn pud_pfn
static inline unsigned long pud_pfn(pud_t pud)
{
return __pa(pud_deref(pud)) >> PAGE_SHIFT;
--- a/arch/sparc/include/asm/pgtable_64.h~mm-arch-provide-pud_pfn-fallback
+++ a/arch/sparc/include/asm/pgtable_64.h
@@ -875,6 +875,7 @@ static inline bool pud_leaf(pud_t pud)
return pte_val(pte) & _PAGE_PMD_HUGE;
}
+#define pud_pfn pud_pfn
static inline unsigned long pud_pfn(pud_t pud)
{
pte_t pte = __pte(pud_val(pud));
--- a/arch/x86/include/asm/pgtable.h~mm-arch-provide-pud_pfn-fallback
+++ a/arch/x86/include/asm/pgtable.h
@@ -234,6 +234,7 @@ static inline unsigned long pmd_pfn(pmd_
return (pfn & pmd_pfn_mask(pmd)) >> PAGE_SHIFT;
}
+#define pud_pfn pud_pfn
static inline unsigned long pud_pfn(pud_t pud)
{
phys_addr_t pfn = pud_val(pud);
--- a/include/linux/pgtable.h~mm-arch-provide-pud_pfn-fallback
+++ a/include/linux/pgtable.h
@@ -1820,6 +1820,16 @@ typedef unsigned int pgtbl_mod_mask;
#endif
/*
+ * We always define pmd_pfn for all archs as it's used in lots of generic
+ * code. Now it happens too for pud_pfn (and can happen for larger
+ * mappings too in the future; we're not there yet). Instead of defining
+ * it for all archs (like pmd_pfn), provide a fallback.
+ */
+#ifndef pud_pfn
+#define pud_pfn(x) ({ BUILD_BUG(); 0; })
+#endif
+
+/*
* Some architectures have MMUs that are configurable or selectable at boot
* time. These lead to variable PTRS_PER_x. For statically allocated arrays it
* helps to have a static maximum value.
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-hmm-process-pud-swap-entry-without-pud_huge.patch
mm-gup-cache-p4d-in-follow_p4d_mask.patch
mm-gup-check-p4d-presence-before-going-on.patch
mm-x86-change-pxd_huge-behavior-to-exclude-swap-entries.patch
mm-sparc-change-pxd_huge-behavior-to-exclude-swap-entries.patch
mm-arm-use-macros-to-define-pmd-pud-helpers.patch
mm-arm-redefine-pmd_huge-with-pmd_leaf.patch
mm-arm64-merge-pxd_huge-and-pxd_leaf-definitions.patch
mm-powerpc-redefine-pxd_huge-with-pxd_leaf.patch
mm-gup-merge-pxd-huge-mapping-checks.patch
mm-treewide-replace-pxd_huge-with-pxd_leaf.patch
mm-treewide-remove-pxd_huge.patch
mm-arm-remove-pmd_thp_or_huge.patch
mm-document-pxd_leaf-api.patch
selftests-mm-run_vmtestssh-fix-hugetlb-mem-size-calculation.patch
mm-kconfig-config_pgtable_has_huge_leaves.patch
mm-hugetlb-declare-hugetlbfs_pagecache_present-non-static.patch
mm-make-hpage_pxd_-macros-even-if-thp.patch
mm-introduce-vma_pgtable_walk_beginend.patch
mm-arch-provide-pud_pfn-fallback.patch
mm-gup-drop-folio_fast_pin_allowed-in-hugepd-processing.patch
mm-gup-refactor-record_subpages-to-find-1st-small-page.patch
mm-gup-handle-hugetlb-for-no_page_table.patch
mm-gup-cache-pudp-in-follow_pud_mask.patch
mm-gup-handle-huge-pud-for-follow_pud_mask.patch
mm-gup-handle-huge-pmd-for-follow_pmd_mask.patch
mm-gup-handle-hugepd-for-follow_page.patch
mm-gup-handle-hugetlb-in-the-generic-follow_page_mask-code.patch
