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Tue, 4 Mar 2025 07:05:10 -0800 (PST) From: Ryan Roberts To: Catalin Marinas , Will Deacon , Pasha Tatashin , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , David Hildenbrand , "Matthew Wilcox (Oracle)" , Mark Rutland , Anshuman Khandual , Alexandre Ghiti , Kevin Brodsky Cc: Ryan Roberts , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 08/11] mm/vmalloc: Gracefully unmap huge ptes Date: Tue, 4 Mar 2025 15:04:38 +0000 Message-ID: <20250304150444.3788920-9-ryan.roberts@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250304150444.3788920-1-ryan.roberts@arm.com> References: <20250304150444.3788920-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D4C9C1C0010 X-Rspam-User: X-Stat-Signature: oiufsna4mh7i4nd5p9sy8f99e5wg8eg5 X-HE-Tag: 1741100712-385137 X-HE-Meta: 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 L1aJiO57 f6MFJ+8lcrt1eyODLnwB2+FjbMmV3C4Ggb5CiUOf9tPlZ9kqeFphDWSK94xHc9Fe9DjmSNx3+2KzVHz/dKi95FU/y1oAQrcQRWwTIh6XLfTKK1Ov3D0JRt57HFiceYjuuQqOKdsgdwH1yXy8dfe8OwDimHjBBP3DSLtU9kPEpBfiAibWKkCIqya/8PQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Commit f7ee1f13d606 ("mm/vmalloc: enable mapping of huge pages at pte level in vmap") added its support by reusing the set_huge_pte_at() API, which is otherwise only used for user mappings. But when unmapping those huge ptes, it continued to call ptep_get_and_clear(), which is a layering violation. To date, the only arch to implement this support is powerpc and it all happens to work ok for it. But arm64's implementation of ptep_get_and_clear() can not be safely used to clear a previous set_huge_pte_at(). So let's introduce a new arch opt-in function, arch_vmap_pte_range_unmap_size(), which can provide the size of a (present) pte. Then we can call huge_ptep_get_and_clear() to tear it down properly. Note that if vunmap_range() is called with a range that starts in the middle of a huge pte-mapped page, we must unmap the entire huge page so the behaviour is consistent with pmd and pud block mappings. In this case emit a warning just like we do for pmd/pud mappings. Reviewed-by: Anshuman Khandual Reviewed-by: Uladzislau Rezki (Sony) Reviewed-by: Catalin Marinas Signed-off-by: Ryan Roberts --- include/linux/vmalloc.h | 8 ++++++++ mm/vmalloc.c | 18 ++++++++++++++++-- 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 31e9ffd936e3..16dd4cba64f2 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -113,6 +113,14 @@ static inline unsigned long arch_vmap_pte_range_map_size(unsigned long addr, uns } #endif +#ifndef arch_vmap_pte_range_unmap_size +static inline unsigned long arch_vmap_pte_range_unmap_size(unsigned long addr, + pte_t *ptep) +{ + return PAGE_SIZE; +} +#endif + #ifndef arch_vmap_pte_supported_shift static inline int arch_vmap_pte_supported_shift(unsigned long size) { diff --git a/mm/vmalloc.c b/mm/vmalloc.c index fcdf67d5177a..6111ce900ec4 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -350,12 +350,26 @@ static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pgtbl_mod_mask *mask) { pte_t *pte; + pte_t ptent; + unsigned long size = PAGE_SIZE; pte = pte_offset_kernel(pmd, addr); do { - pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte); +#ifdef CONFIG_HUGETLB_PAGE + size = arch_vmap_pte_range_unmap_size(addr, pte); + if (size != PAGE_SIZE) { + if (WARN_ON(!IS_ALIGNED(addr, size))) { + addr = ALIGN_DOWN(addr, size); + pte = PTR_ALIGN_DOWN(pte, sizeof(*pte) * (size >> PAGE_SHIFT)); + } + ptent = huge_ptep_get_and_clear(&init_mm, addr, pte, size); + if (WARN_ON(end - addr < size)) + size = end - addr; + } else +#endif + ptent = ptep_get_and_clear(&init_mm, addr, pte); WARN_ON(!pte_none(ptent) && !pte_present(ptent)); - } while (pte++, addr += PAGE_SIZE, addr != end); + } while (pte += (size >> PAGE_SHIFT), addr += size, addr != end); *mask |= PGTBL_PTE_MODIFIED; }