mm: introduce ctor/dtor at PGD level

Following on from the introduction of P4D-level ctor/dtor, let's finish
the job and introduce ctor/dtor at PGD level.  The incurred improvement in
page accounting is minimal - the main motivation is to create a single,
generic place where construction/destruction hooks can be added for all
page table pages.

This patch should cover all architectures and all configurations where
PGDs are one or more regular pages.  This excludes any configuration where
PGDs are allocated from a kmem_cache object.

Link: https://lkml.kernel.org/r/20250103184415.2744423-7-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/m68k/include/asm/mcf_pgalloc.h b/arch/m68k/include/asm/mcf_pgalloc.h
index 22d6c1f..4c648b5 100644 (file)
--- a/arch/m68k/include/asm/mcf_pgalloc.h
+++ b/arch/m68k/include/asm/mcf_pgalloc.h
@@ -73,7 +73,7 @@ static inline void pte_free(struct mm_struct *mm, pgtable_t pgtable)
 
 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 {
-       pagetable_free(virt_to_ptdesc(pgd));
+       pagetable_dtor_free(virt_to_ptdesc(pgd));
 }
 
 static inline pgd_t *pgd_alloc(struct mm_struct *mm)
@@ -84,6 +84,7 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
 
        if (!ptdesc)
                return NULL;
+       pagetable_pgd_ctor(ptdesc);
        new_pgd = ptdesc_address(ptdesc);
 
        memcpy(new_pgd, swapper_pg_dir, PTRS_PER_PGD * sizeof(pgd_t));

diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
index 12de00d..0fb8b09 100644 (file)
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -169,6 +169,9 @@ void *get_pointer_table(int type)
                case TABLE_PMD:
                        pagetable_pmd_ctor(virt_to_ptdesc(page));
                        break;
+               case TABLE_PGD:
+                       pagetable_pgd_ctor(virt_to_ptdesc(page));
+                       break;
                }
 
                mmu_page_ctor(page);
@@ -207,8 +210,7 @@ int free_pointer_table(void *table, int type)
                /* all tables in page are free, free page */
                list_del(dp);
                mmu_page_dtor((void *)page);
-               if (type == TABLE_PTE || type == TABLE_PMD)
-                       pagetable_dtor(virt_to_ptdesc((void *)page));
+               pagetable_dtor(virt_to_ptdesc((void *)page));
                free_page (page);
                return 1;
        } else if (ptable_list[type].next != dp) {

diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index 5fced6d..b19b6ed 100644 (file)
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -130,11 +130,18 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 
 static inline pgd_t *pgd_alloc(struct mm_struct *mm)
 {
-       return (pgd_t *) crst_table_alloc(mm);
+       unsigned long *table = crst_table_alloc(mm);
+
+       if (!table)
+               return NULL;
+       pagetable_pgd_ctor(virt_to_ptdesc(table));
+
+       return (pgd_t *) table;
 }
 
 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 {
+       pagetable_dtor(virt_to_ptdesc(pgd));
        crst_table_free(mm, (unsigned long *) pgd);
 }
 

diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index de4df14..892ece4 100644 (file)
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -271,6 +271,7 @@ static inline pgd_t *__pgd_alloc_noprof(struct mm_struct *mm, unsigned int order
        if (!ptdesc)
                return NULL;
 
+       pagetable_pgd_ctor(ptdesc);
        return ptdesc_address(ptdesc);
 }
 #define __pgd_alloc(...)       alloc_hooks(__pgd_alloc_noprof(__VA_ARGS__))
@@ -280,7 +281,7 @@ static inline void __pgd_free(struct mm_struct *mm, pgd_t *pgd)
        struct ptdesc *ptdesc = virt_to_ptdesc(pgd);
 
        BUG_ON((unsigned long)pgd & (PAGE_SIZE-1));
-       pagetable_free(ptdesc);
+       pagetable_dtor_free(ptdesc);
 }
 
 #ifndef __HAVE_ARCH_PGD_FREE

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2949b58..3550cbe 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3159,6 +3159,11 @@ static inline void pagetable_p4d_ctor(struct ptdesc *ptdesc)
        __pagetable_ctor(ptdesc);
 }
 
+static inline void pagetable_pgd_ctor(struct ptdesc *ptdesc)
+{
+       __pagetable_ctor(ptdesc);
+}
+
 extern void __init pagecache_init(void);
 extern void free_initmem(void);