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pgtable: create struct ptdesc

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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/20230807230513.102486-3-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Guo Ren <guoren@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Vishal Moola (Oracle) 2023-08-07 16:04:44 -07:00 committed by Andrew Morton
parent f7bda0d85d
commit 9a35de4ffc
1 changed files with 70 additions and 0 deletions
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70
include/linux/mm_types.h
View File

@ -397,6 +397,76 @@ FOLIO_MATCH(flags, _flags_2);
FOLIO_MATCH(compound_head, _head_2);
#undef FOLIO_MATCH
/**
* 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));
/*
* Used for sizing the vmemmap region on some architectures
*/