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[174.95.95.253]) by smtp.gmail.com with ESMTPSA id y15sm308813qth.52.2021.02.23.07.38.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Feb 2021 07:38:42 -0800 (PST) Date: Tue, 23 Feb 2021 10:38:40 -0500 From: Peter Xu To: Axel Rasmussen Cc: Alexander Viro , Alexey Dobriyan , Andrea Arcangeli , Andrew Morton , Anshuman Khandual , Catalin Marinas , Chinwen Chang , Huang Ying , Ingo Molnar , Jann Horn , Jerome Glisse , Lokesh Gidra , "Matthew Wilcox (Oracle)" , Michael Ellerman , Michal =?utf-8?Q?Koutn=C3=BD?= , Michel Lespinasse , Mike Kravetz , Mike Rapoport , Nicholas Piggin , Shaohua Li , Shawn Anastasio , Steven Rostedt , Steven Price , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Adam Ruprecht , Cannon Matthews , "Dr . David Alan Gilbert" , David Rientjes , Mina Almasry , Oliver Upton Subject: Re: [PATCH v7 4/6] userfaultfd: add UFFDIO_CONTINUE ioctl Message-ID: <20210223153840.GB154711@xz-x1> References: <20210219004824.2899045-1-axelrasmussen@google.com> <20210219004824.2899045-5-axelrasmussen@google.com> MIME-Version: 1.0 In-Reply-To: <20210219004824.2899045-5-axelrasmussen@google.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7CC404080F46 X-Stat-Signature: nhun9wxwk6846nqsk9qrursgjo9mfjes Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf26; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614094725-770693 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: On Thu, Feb 18, 2021 at 04:48:22PM -0800, Axel Rasmussen wrote: > @@ -4645,8 +4646,18 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, > spinlock_t *ptl; > int ret; > struct page *page; > + int writable; > > - if (!*pagep) { > + mapping = dst_vma->vm_file->f_mapping; > + idx = vma_hugecache_offset(h, dst_vma, dst_addr); > + > + if (is_continue) { > + ret = -EFAULT; > + page = find_lock_page(mapping, idx); > + *pagep = NULL; Why set *pagep to NULL? Shouldn't it be NULL always?.. If that's the case, maybe WARN_ON_ONCE(*pagep) suite more. Otherwise the patch looks good to me. Thanks, -- Peter Xu