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Wed, 15 Jul 2026 05:08:44 -0700 (PDT) From: Wen Jiang X-Google-Original-From: Wen Jiang To: akpm@linux-foundation.org, catalin.marinas@arm.com, linux-mm@kvack.org, urezki@gmail.com, will@kernel.org Cc: Xueyuan.chen21@gmail.com, ajd@linux.ibm.com, anshuman.khandual@arm.com, david@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, rppt@kernel.org, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, Wen Jiang , Xueyuan Chen , Leo Yan Subject: [PATCH v7 4/7] mm/vmalloc: Extend page table walk to support larger page_shift sizes and eliminate page table rewalk Date: Wed, 15 Jul 2026 20:08:10 +0800 Message-Id: <20260715120813.3609949-5-jiangwen6@xiaomi.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260715120813.3609949-1-jiangwen6@xiaomi.com> References: <20260715120813.3609949-1-jiangwen6@xiaomi.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Barry Song (Xiaomi)" vmap_pages_range_noflush_walk() (formerly vmap_small_pages_range_noflush()) provides a clean interface by taking struct page **pages and mapping them via direct PTE iteration. This avoids the page table rewalk seen when using vmap_range_noflush() for page_shift values other than PAGE_SHIFT. Extend it to support larger page_shift values, and add PMD- and contiguous-PTE mappings as well. Rename it to vmap_pages_range_noflush_walk() since it now handles more than just small pages. For vmalloc() allocations with VM_ALLOW_HUGE_VMAP, we no longer need to iterate over pages one by one via vmap_range_noflush(), which would otherwise lead to page table rewalk. The code is now unified with the PAGE_SHIFT case by simply calling vmap_pages_range_noflush_walk(). Signed-off-by: Barry Song (Xiaomi) Signed-off-by: Wen Jiang Tested-by: Xueyuan Chen Tested-by: Leo Yan Reviewed-by: Dev Jain --- mm/vmalloc.c | 86 +++++++++++++++++++++++++++++++--------------------- 1 file changed, 52 insertions(+), 34 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index b9b29f7857bb2..afc695d5973e8 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -541,8 +541,10 @@ void vunmap_range(unsigned long addr, unsigned long end) static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, int *nr, - pgtbl_mod_mask *mask) + pgtbl_mod_mask *mask, unsigned int shift) { + unsigned long pfn, size; + unsigned int steps; int err = 0; pte_t *pte; @@ -573,9 +575,10 @@ static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr, break; } - set_pte_at(&init_mm, addr, pte, mk_pte(page, prot)); - (*nr)++; - } while (pte++, addr += PAGE_SIZE, addr != end); + pfn = page_to_pfn(page); + size = vmap_set_ptes(pte, addr, end, pfn, prot, shift); + steps = PFN_DOWN(size); + } while (pte += steps, *nr += steps, addr += size, addr != end); lazy_mmu_mode_disable(); *mask |= PGTBL_PTE_MODIFIED; @@ -585,60 +588,90 @@ static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr, static int vmap_pages_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, int *nr, - pgtbl_mod_mask *mask) + pgtbl_mod_mask *mask, unsigned int shift) { pmd_t *pmd; unsigned long next; + int err; pmd = pmd_alloc_track(&init_mm, pud, addr, mask); if (!pmd) return -ENOMEM; do { next = pmd_addr_end(addr, end); - if (vmap_pages_pte_range(pmd, addr, next, prot, pages, nr, mask)) - return -ENOMEM; + + if (shift >= PMD_SHIFT) { + struct page *page = pages[*nr]; + phys_addr_t phys_addr; + + if (WARN_ON(!page)) + return -ENOMEM; + if (WARN_ON(!pfn_valid(page_to_pfn(page)))) + return -EINVAL; + + phys_addr = page_to_phys(page); + + if (vmap_try_huge_pmd(pmd, addr, next, phys_addr, prot, + shift)) { + *mask |= PGTBL_PMD_MODIFIED; + *nr += 1 << (PMD_SHIFT - PAGE_SHIFT); + continue; + } + } + + err = vmap_pages_pte_range(pmd, addr, next, prot, pages, nr, mask, shift); + if (err) + return err; } while (pmd++, addr = next, addr != end); return 0; } static int vmap_pages_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, int *nr, - pgtbl_mod_mask *mask) + pgtbl_mod_mask *mask, unsigned int shift) { pud_t *pud; unsigned long next; + int err; pud = pud_alloc_track(&init_mm, p4d, addr, mask); if (!pud) return -ENOMEM; do { next = pud_addr_end(addr, end); - if (vmap_pages_pmd_range(pud, addr, next, prot, pages, nr, mask)) - return -ENOMEM; + err = vmap_pages_pmd_range(pud, addr, next, prot, pages, nr, mask, shift); + if (err) + return err; } while (pud++, addr = next, addr != end); return 0; } static int vmap_pages_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, int *nr, - pgtbl_mod_mask *mask) + pgtbl_mod_mask *mask, unsigned int shift) { p4d_t *p4d; unsigned long next; + int err; p4d = p4d_alloc_track(&init_mm, pgd, addr, mask); if (!p4d) return -ENOMEM; do { next = p4d_addr_end(addr, end); - if (vmap_pages_pud_range(p4d, addr, next, prot, pages, nr, mask)) - return -ENOMEM; + err = vmap_pages_pud_range(p4d, addr, next, prot, pages, nr, mask, shift); + if (err) + return err; } while (p4d++, addr = next, addr != end); return 0; } -static int vmap_small_pages_range_noflush(unsigned long addr, unsigned long end, - pgprot_t prot, struct page **pages) +/* + * It can take an array of pages which are not all contiguous, but it + * may have contiguous chunks, as hinted by @shift. + */ +static int vmap_pages_range_noflush_walk(unsigned long addr, unsigned long end, + pgprot_t prot, struct page **pages, unsigned int shift) { unsigned long start = addr; pgd_t *pgd; @@ -653,7 +686,7 @@ static int vmap_small_pages_range_noflush(unsigned long addr, unsigned long end, next = pgd_addr_end(addr, end); if (pgd_bad(*pgd)) mask |= PGTBL_PGD_MODIFIED; - err = vmap_pages_p4d_range(pgd, addr, next, prot, pages, &nr, &mask); + err = vmap_pages_p4d_range(pgd, addr, next, prot, pages, &nr, &mask, shift); if (err) break; } while (pgd++, addr = next, addr != end); @@ -676,27 +709,12 @@ static int vmap_small_pages_range_noflush(unsigned long addr, unsigned long end, int __vmap_pages_range_noflush(unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, unsigned int page_shift) { - unsigned int i, nr = (end - addr) >> PAGE_SHIFT; - WARN_ON(page_shift < PAGE_SHIFT); - if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || - page_shift == PAGE_SHIFT) - return vmap_small_pages_range_noflush(addr, end, prot, pages); + if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC)) + page_shift = PAGE_SHIFT; - for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) { - int err; - - err = vmap_range_noflush(addr, addr + (1UL << page_shift), - page_to_phys(pages[i]), prot, - page_shift); - if (err) - return err; - - addr += 1UL << page_shift; - } - - return 0; + return vmap_pages_range_noflush_walk(addr, end, prot, pages, page_shift); } int vmap_pages_range_noflush(unsigned long addr, unsigned long end, -- 2.34.1