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Shutemov" , Hugh Dickins , Axel Rasmussen , Matthew Wilcox , Andrew Morton , Andrea Arcangeli , Nadav Amit Subject: [PATCH RFC 20/30] hugetlb/userfaultfd: Handle UFFDIO_WRITEPROTECT Date: Fri, 15 Jan 2021 12:08:57 -0500 Message-Id: <20210115170907.24498-21-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210115170907.24498-1-peterx@redhat.com> References: <20210115170907.24498-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This starts from passing cp_flags into hugetlb_change_protection() so hugetlb will be able to handle MM_CP_UFFD_WP[_RESOLVE] requests. huge_pte_clear_uffd_wp() is introduced to handle the case where the UFFDIO_WRITEPROTECT is requested upon migrating huge page entries. Signed-off-by: Peter Xu --- include/asm-generic/hugetlb.h | 5 +++++ include/linux/hugetlb.h | 6 ++++-- mm/hugetlb.c | 13 ++++++++++++- mm/mprotect.c | 3 ++- mm/userfaultfd.c | 8 ++++++++ 5 files changed, 31 insertions(+), 4 deletions(-) diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h index 548212eccbd6..181cdc3297e7 100644 --- a/include/asm-generic/hugetlb.h +++ b/include/asm-generic/hugetlb.h @@ -32,6 +32,11 @@ static inline pte_t huge_pte_mkuffd_wp(pte_t pte) return pte_mkuffd_wp(pte); } +static inline pte_t huge_pte_clear_uffd_wp(pte_t pte) +{ + return pte_clear_uffd_wp(pte); +} + static inline pte_t huge_pte_modify(pte_t pte, pgprot_t newprot) { return pte_modify(pte, newprot); diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index bd061f7eedcb..fe1dde0afbaf 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -185,7 +185,8 @@ struct page *follow_huge_pgd(struct mm_struct *mm, unsigned long address, int pmd_huge(pmd_t pmd); int pud_huge(pud_t pud); unsigned long hugetlb_change_protection(struct vm_area_struct *vma, - unsigned long address, unsigned long end, pgprot_t newprot); + unsigned long address, unsigned long end, pgprot_t newprot, + unsigned long cp_flags); bool is_hugetlb_entry_migration(pte_t pte); @@ -343,7 +344,8 @@ static inline void move_hugetlb_state(struct page *oldpage, static inline unsigned long hugetlb_change_protection( struct vm_area_struct *vma, unsigned long address, - unsigned long end, pgprot_t newprot) + unsigned long end, pgprot_t newprot, + unsigned long cp_flags) { return 0; } diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 563b8f70537f..18b236bac6cd 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4938,7 +4938,8 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, #endif unsigned long hugetlb_change_protection(struct vm_area_struct *vma, - unsigned long address, unsigned long end, pgprot_t newprot) + unsigned long address, unsigned long end, + pgprot_t newprot, unsigned long cp_flags) { struct mm_struct *mm = vma->vm_mm; unsigned long start = address; @@ -4948,6 +4949,8 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, unsigned long pages = 0; bool shared_pmd = false; struct mmu_notifier_range range; + bool uffd_wp = cp_flags & MM_CP_UFFD_WP; + bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; /* * In the case of shared PMDs, the area to flush could be beyond @@ -4988,6 +4991,10 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, make_migration_entry_read(&entry); newpte = swp_entry_to_pte(entry); + if (uffd_wp) + newpte = pte_swp_mkuffd_wp(newpte); + else if (uffd_wp_resolve) + newpte = pte_swp_clear_uffd_wp(newpte); set_huge_swap_pte_at(mm, address, ptep, newpte, huge_page_size(h)); pages++; @@ -5001,6 +5008,10 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, old_pte = huge_ptep_modify_prot_start(vma, address, ptep); pte = pte_mkhuge(huge_pte_modify(old_pte, newprot)); pte = arch_make_huge_pte(pte, vma, NULL, 0); + if (uffd_wp) + pte = huge_pte_mkuffd_wp(huge_pte_wrprotect(pte)); + else if (uffd_wp_resolve) + pte = huge_pte_clear_uffd_wp(pte); huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte); pages++; } diff --git a/mm/mprotect.c b/mm/mprotect.c index 055871322007..fce87ac99117 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -416,7 +416,8 @@ unsigned long change_protection(struct vm_area_struct *vma, unsigned long start, BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); if (is_vm_hugetlb_page(vma)) - pages = hugetlb_change_protection(vma, start, end, newprot); + pages = hugetlb_change_protection(vma, start, end, newprot, + cp_flags); else pages = change_protection_range(vma, start, end, newprot, cp_flags); diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index b00e5e6b8b8b..480d91b783d4 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -644,6 +644,7 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, unsigned long len, bool enable_wp, bool *mmap_changing) { struct vm_area_struct *dst_vma; + unsigned long page_mask; pgprot_t newprot; int err; @@ -680,6 +681,13 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, if (!vma_is_anonymous(dst_vma)) goto out_unlock; + if (is_vm_hugetlb_page(dst_vma)) { + err = -EINVAL; + page_mask = vma_kernel_pagesize(dst_vma) - 1; + if ((start & page_mask) || (len & page_mask)) + goto out_unlock; + } + if (enable_wp) newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE)); else -- 2.26.2