diff options
| author | Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> | 2023-07-25 00:37:49 +0530 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-08-18 10:12:53 -0700 |
| commit | c1a6c536fb088c01d6bdce77731d89ad5e1734c6 (patch) | |
| tree | bc883e4fee5037a319e88a98538e6cd0c475cb57 | |
| parent | f32928ab6fe5abac5a270b6c0bffc4ce77ee8c42 (diff) | |
mm/vmemmap: improve vmemmap_can_optimize and allow architectures to override
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@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/mm.h | 27 | ||||
| -rw-r--r-- | mm/mm_init.c | 2 |
2 files changed, 24 insertions, 5 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 21299a0cfbca..d4ce73c20dcc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3632,13 +3632,32 @@ void vmemmap_free(unsigned long start, unsigned long end, 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) diff --git a/mm/mm_init.c b/mm/mm_init.c index acb0ac194672..641c56fd08a2 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1020,7 +1020,7 @@ static inline unsigned long compound_nr_pages(struct vmem_altmap *altmap, 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, |