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Sat, 07 Nov 2026 05:50:47 -0800 (PST) Received: from mi-OptiPlex-7060.mioffice.cn ([43.224.245.234]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36fa922c6c7sm21280820eec.10.2026.11.07.05.50.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Nov 2026 05:50:46 -0800 (PST) From: Wen Jiang To: akpm@linux-foundation.org, catalin.marinas@arm.com, will@kernel.org, urezki@gmail.com, linux-mm@kvack.org Cc: baohua@kernel.org, dev.jain@arm.com, ryan.roberts@arm.com, anshuman.khandual@arm.com, david@kernel.org, rppt@kernel.org, leo.yan@arm.com, xueyuan.chen21@gmail.com, chleroy@kernel.org, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, ajd@linux.ibm.com, jiangwen6@xiaomi.com, jiangwenxiaomi@gmail.com, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH v12 07/10] mm/vmalloc: extend page table walk to support larger page_shift sizes and eliminate page table rewalk Date: Sat, 7 Nov 2026 21:49:50 +0800 Message-Id: <20261107134953.748622-8-jiangwenxiaomi@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261107134953.748622-1-jiangwenxiaomi@gmail.com> References: <20261107134953.748622-1-jiangwenxiaomi@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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(). The pages array may hold several physically discontiguous chunks that are mapped with the same @shift. If the virtual range is not aligned to the chunk size, a PMD boundary can split a chunk, and the walk resumes in the next PMD in the middle of it. arch_vmap_pte_range_map_size() only checks CONT_PTE_SIZE alignment there and could map past the end of the chunk, so clamp each PTE-level mapping to the remainder of the current chunk. Signed-off-by: Barry Song (Xiaomi) Signed-off-by: Wen Jiang Tested-by: Xueyuan Chen Tested-by: Leo Yan Reviewed-by: Dev Jain Reviewed-by: Uladzislau Rezki (Sony) --- mm/vmalloc.c | 88 ++++++++++++++++++++++++++++++++-------------------- 1 file changed, 54 insertions(+), 34 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index e3ea9581e68d0..f2dd9bef4de0f 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -558,8 +558,11 @@ 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) { + const unsigned long chunk_pages = 1UL << (shift - PAGE_SHIFT); + unsigned long pfn, size, chunk_end; + unsigned int nr_pages; int err = 0; pte_t *pte; @@ -590,9 +593,13 @@ 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); + + /* A PMD boundary may split a chunk; never map past its end. */ + chunk_end = addr + ((ALIGN(pfn + 1, chunk_pages) - pfn) << PAGE_SHIFT); + size = vmap_set_ptes(pte, addr, min(end, chunk_end), pfn, prot, shift); + nr_pages = PFN_DOWN(size); + } while (pte += nr_pages, *nr += nr_pages, addr += size, addr != end); lazy_mmu_mode_disable(); *mask |= PGTBL_PTE_MODIFIED; @@ -602,60 +609,88 @@ 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 += 1U << (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; @@ -670,7 +705,7 @@ 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); @@ -693,28 +728,13 @@ 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; - if (WARN_ON_ONCE(page_shift < PAGE_SHIFT)) return -EINVAL; - 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