The patch titled
Subject: pgtable: create struct ptdesc
has been added to the -mm mm-unstable branch. Its filename is
pgtable-create-struct-ptdesc.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/pgtable-create-struct-ptdesc.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: "Vishal Moola (Oracle)" <vishal.moola@xxxxxxxxx>
Subject: pgtable: create struct ptdesc
Date: Mon, 31 Jul 2023 10:03:03 -0700
Currently, page table information is stored within struct page. As part
of simplifying struct page, create struct ptdesc for page table
information.
Link: https://lkml.kernel.org/r/20230731170332.69404-3-vishal.moola@xxxxxxxxx
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Acked-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Dinh Nguyen <dinguyen@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Cc: Guo Ren <guoren@xxxxxxxxxx>
Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
Cc: Jonas Bonn <jonas@xxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pgtable.h | 71 ++++++++++++++++++++++++++++++++++++++
1 file changed, 71 insertions(+)
--- a/include/linux/pgtable.h~pgtable-create-struct-ptdesc
+++ a/include/linux/pgtable.h
@@ -998,6 +998,77 @@ static inline void ptep_modify_prot_comm
#endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */
#endif /* CONFIG_MMU */
+
+/**
+ * struct ptdesc - Memory descriptor for page tables.
+ * @__page_flags: Same as page flags. Unused for page tables.
+ * @pt_rcu_head: For freeing page table pages.
+ * @pt_list: List of used page tables. Used for s390 and x86.
+ * @_pt_pad_1: Padding that aliases with page's compound head.
+ * @pmd_huge_pte: Protected by ptdesc->ptl, used for THPs.
+ * @__page_mapping: Aliases with page->mapping. Unused for page tables.
+ * @pt_mm: Used for x86 pgds.
+ * @pt_frag_refcount: For fragmented page table tracking. Powerpc and s390 only.
+ * @_pt_pad_2: Padding to ensure proper alignment.
+ * @ptl: Lock for the page table.
+ * @__page_type: Same as page->page_type. Unused for page tables.
+ * @_refcount: Same as page refcount. Used for s390 page tables.
+ * @pt_memcg_data: Memcg data. Tracked for page tables here.
+ *
+ * This struct overlays struct page for now. Do not modify without a good
+ * understanding of the issues.
+ */
+struct ptdesc {
+ unsigned long __page_flags;
+
+ union {
+ struct rcu_head pt_rcu_head;
+ struct list_head pt_list;
+ struct {
+ unsigned long _pt_pad_1;
+ pgtable_t pmd_huge_pte;
+ };
+ };
+ unsigned long __page_mapping;
+
+ union {
+ struct mm_struct *pt_mm;
+ atomic_t pt_frag_refcount;
+ };
+
+ union {
+ unsigned long _pt_pad_2;
+#if ALLOC_SPLIT_PTLOCKS
+ spinlock_t *ptl;
+#else
+ spinlock_t ptl;
+#endif
+ };
+ unsigned int __page_type;
+ atomic_t _refcount;
+#ifdef CONFIG_MEMCG
+ unsigned long pt_memcg_data;
+#endif
+};
+
+#define TABLE_MATCH(pg, pt) \
+ static_assert(offsetof(struct page, pg) == offsetof(struct ptdesc, pt))
+TABLE_MATCH(flags, __page_flags);
+TABLE_MATCH(compound_head, pt_list);
+TABLE_MATCH(compound_head, _pt_pad_1);
+TABLE_MATCH(pmd_huge_pte, pmd_huge_pte);
+TABLE_MATCH(mapping, __page_mapping);
+TABLE_MATCH(pt_mm, pt_mm);
+TABLE_MATCH(ptl, ptl);
+TABLE_MATCH(rcu_head, pt_rcu_head);
+TABLE_MATCH(page_type, __page_type);
+TABLE_MATCH(_refcount, _refcount);
+#ifdef CONFIG_MEMCG
+TABLE_MATCH(memcg_data, pt_memcg_data);
+#endif
+#undef TABLE_MATCH
+static_assert(sizeof(struct ptdesc) <= sizeof(struct page));
+
/*
* No-op macros that just return the current protection value. Defined here
* because these macros can be used even if CONFIG_MMU is not defined.
_
Patches currently in -mm which might be from vishal.moola@xxxxxxxxx are
mm-add-page_type_op-folio-functions.patch
pgtable-create-struct-ptdesc.patch
mm-add-utility-functions-for-ptdesc.patch
mm-convert-pmd_pgtable_page-callers-to-use-pmd_ptdesc.patch
mm-convert-ptlock_alloc-to-use-ptdescs.patch
mm-convert-ptlock_ptr-to-use-ptdescs.patch
mm-convert-pmd_ptlock_init-to-use-ptdescs.patch
mm-convert-ptlock_init-to-use-ptdescs.patch
mm-convert-pmd_ptlock_free-to-use-ptdescs.patch
mm-convert-ptlock_free-to-use-ptdescs.patch
mm-create-ptdesc-equivalents-for-pgtable_ptepmd_page_ctordtor.patch
powerpc-convert-various-functions-to-use-ptdescs.patch
x86-convert-various-functions-to-use-ptdescs.patch
s390-convert-various-pgalloc-functions-to-use-ptdescs.patch
mm-remove-page-table-members-from-struct-page.patch
pgalloc-convert-various-functions-to-use-ptdescs.patch
arm-convert-various-functions-to-use-ptdescs.patch
arm64-convert-various-functions-to-use-ptdescs.patch
csky-convert-__pte_free_tlb-to-use-ptdescs.patch
hexagon-convert-__pte_free_tlb-to-use-ptdescs.patch
loongarch-convert-various-functions-to-use-ptdescs.patch
m68k-convert-various-functions-to-use-ptdescs.patch
mips-convert-various-functions-to-use-ptdescs.patch
nios2-convert-__pte_free_tlb-to-use-ptdescs.patch
openrisc-convert-__pte_free_tlb-to-use-ptdescs.patch
riscv-convert-alloc_pmd-pte_late-to-use-ptdescs.patch
sh-convert-pte_free_tlb-to-use-ptdescs.patch
sparc64-convert-various-functions-to-use-ptdescs.patch
sparc-convert-pgtable_pte_page_ctor-dtor-to-ptdesc-equivalents.patch
um-convert-pmd-pte_free_tlb-to-use-ptdescs.patch
mm-remove-pgtable_pmd-pte_page_ctor-dtor-wrappers.patch
