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[99.241.198.116]) by smtp.gmail.com with ESMTPSA id y8-20020a920908000000b002ca38acaa60sm2917919ilg.81.2022.04.04.18.49.02 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 04 Apr 2022 18:49:03 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Mike Kravetz , Nadav Amit , Matthew Wilcox , Mike Rapoport , David Hildenbrand , Hugh Dickins , Jerome Glisse , "Kirill A . Shutemov" , Andrea Arcangeli , Andrew Morton , Axel Rasmussen , Alistair Popple , peterx@redhat.com Subject: [PATCH v8 12/23] mm/hugetlb: Hook page faults for uffd write protection Date: Mon, 4 Apr 2022 21:49:01 -0400 Message-Id: <20220405014901.14590-1-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220405014646.13522-1-peterx@redhat.com> References: <20220405014646.13522-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hook up hugetlbfs_fault() with the capability to handle userfaultfd-wp faults. We do this slightly earlier than hugetlb_cow() so that we can avoid taking some extra locks that we definitely don't need. Reviewed-by: Mike Kravetz Signed-off-by: Peter Xu --- mm/hugetlb.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index dd642cfc538b..82df0fcfedf9 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5711,6 +5711,26 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) goto out_ptl; + /* Handle userfault-wp first, before trying to lock more pages */ + if (userfaultfd_wp(vma) && huge_pte_uffd_wp(huge_ptep_get(ptep)) && + (flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) { + struct vm_fault vmf = { + .vma = vma, + .address = haddr, + .real_address = address, + .flags = flags, + }; + + spin_unlock(ptl); + if (pagecache_page) { + unlock_page(pagecache_page); + put_page(pagecache_page); + } + mutex_unlock(&hugetlb_fault_mutex_table[hash]); + i_mmap_unlock_read(mapping); + return handle_userfault(&vmf, VM_UFFD_WP); + } + /* * hugetlb_wp() requires page locks of pte_page(entry) and * pagecache_page, so here we need take the former one -- 2.32.0