DAX compound vmemmap population still reserves one extra tail vmemmap page after the head page, and only maps the remaining tail pages through the shared tail page.
Drop that extra reservation and let the shared tail page cover all tail vmemmap pages after the head page, so DAX follows the same reservation model as HugeTLB. This reduces the reserved vmemmap pages for optimized DAX mappings to OPTIMIZED_FOLIO_VMEMMAP_PAGES and removes the now-unneeded first-tail population from the generic and powerpc paths. Signed-off-by: Muchun Song <[email protected]> --- arch/powerpc/mm/book3s64/radix_pgtable.c | 44 +----------------------- include/linux/mm.h | 2 +- mm/sparse-vmemmap.c | 8 +---- 3 files changed, 3 insertions(+), 51 deletions(-) diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c index 95e65ac8cdea..fb8738016b30 100644 --- a/arch/powerpc/mm/book3s64/radix_pgtable.c +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c @@ -1217,39 +1217,6 @@ int __meminit radix__vmemmap_populate(unsigned long start, unsigned long end, in return 0; } -static pte_t * __meminit radix__vmemmap_populate_address(unsigned long addr, int node, - struct vmem_altmap *altmap, - struct page *reuse) -{ - pgd_t *pgd; - p4d_t *p4d; - pud_t *pud; - pmd_t *pmd; - pte_t *pte; - - pgd = pgd_offset_k(addr); - p4d = p4d_offset(pgd, addr); - pud = vmemmap_pud_alloc(p4d, node, addr); - if (!pud) - return NULL; - pmd = vmemmap_pmd_alloc(pud, node, addr); - if (!pmd) - return NULL; - if (pmd_leaf(*pmd)) - /* - * The second page is mapped as a hugepage due to a nearby request. - * Force our mapping to page size without deduplication - */ - return NULL; - pte = vmemmap_pte_alloc(pmd, node, addr); - if (!pte) - return NULL; - radix__vmemmap_pte_populate(pmd, addr, node, NULL, NULL); - vmemmap_verify(pte, node, addr, addr + PAGE_SIZE); - - return pte; -} - int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn, unsigned long start, unsigned long end, int node, @@ -1316,16 +1283,7 @@ int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn, return -ENOMEM; vmemmap_verify(pte, node, addr, addr + PAGE_SIZE); - /* - * Populate the tail pages vmemmap page - * It can fall in different pmd, hence - * vmemmap_populate_address() - */ - pte = radix__vmemmap_populate_address(addr + PAGE_SIZE, node, NULL, NULL); - if (!pte) - return -ENOMEM; - - next = addr + 2 * PAGE_SIZE; + next = addr + PAGE_SIZE; continue; } diff --git a/include/linux/mm.h b/include/linux/mm.h index 5281f073230c..86d7cecb834e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4898,7 +4898,7 @@ static inline void vmem_altmap_free(struct vmem_altmap *altmap, } #endif -#define VMEMMAP_RESERVE_NR 2 +#define VMEMMAP_RESERVE_NR OPTIMIZED_FOLIO_VMEMMAP_PAGES #ifdef CONFIG_ARCH_WANT_OPTIMIZE_DAX_VMEMMAP static inline bool __vmemmap_can_optimize(struct vmem_altmap *altmap, struct dev_pagemap *pgmap) diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index 0c0b54e94c07..b5c109b8af6f 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -473,17 +473,11 @@ static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn, if (!pte) return -ENOMEM; - /* Populate the tail pages vmemmap page */ - next = addr + PAGE_SIZE; - pte = vmemmap_populate_address(next, node, NULL, -1); - if (!pte) - return -ENOMEM; - /* * Reuse the shared page for the rest of tail pages * See layout diagram in Documentation/mm/vmemmap_dedup.rst */ - next += PAGE_SIZE; + next = addr + PAGE_SIZE; rc = vmemmap_populate_range(next, last, node, NULL, page_to_pfn(page)); if (rc) -- 2.54.0
