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[184.145.4.219]) by smtp.gmail.com with ESMTPSA id m15sm2005366qtn.47.2021.05.27.13.23.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 May 2021 13:23:14 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Mike Rapoport , peterx@redhat.com, Andrew Morton , Mike Kravetz , Jerome Glisse , Miaohe Lin , Nadav Amit , Hugh Dickins , Matthew Wilcox , Jason Gunthorpe , "Kirill A . Shutemov" , Andrea Arcangeli , Axel Rasmussen Subject: [PATCH v3 18/27] hugetlb/userfaultfd: Hook page faults for uffd write protection Date: Thu, 27 May 2021 16:23:11 -0400 Message-Id: <20210527202311.31937-1-peterx@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210527201927.29586-1-peterx@redhat.com> References: <20210527201927.29586-1-peterx@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="US-ASCII" Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=J2oaq7rt; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf14.hostedemail.com: domain of peterx@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=peterx@redhat.com X-Stat-Signature: yr6fo9ugwqy7h9ozp1qd9dfbm6uq3za7 X-Rspamd-Queue-Id: 47196C007748 X-Rspamd-Server: rspam02 X-HE-Tag: 1622146990-551517 Content-Transfer-Encoding: quoted-printable 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: Hook up hugetlbfs_fault() with the capability to handle userfaultfd-wp fa= ults. We do this slightly earlier than hugetlb_cow() so that we can avoid takin= g some extra locks that we definitely don't need. Reviewed-by: Mike Kravetz Signed-off-by: Peter Xu --- mm/hugetlb.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 69a4b551c157..4cbbffd50080 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4980,6 +4980,25 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, str= uct vm_area_struct *vma, if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) goto out_ptl; =20 + /* 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 =3D { + .vma =3D vma, + .address =3D haddr, + .flags =3D 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_cow() requires page locks of pte_page(entry) and * pagecache_page, so here we need take the former one --=20 2.31.1