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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id c25-20020ac86619000000b004195faf1e2csm1154119qtp.97.2023.09.28.09.24.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Sep 2023 09:24:56 -0700 (PDT) Date: Thu, 28 Sep 2023 12:24:53 -0400 From: Peter Xu To: David Hildenbrand Cc: Jann Horn , Suren Baghdasaryan , akpm@linux-foundation.org, viro@zeniv.linux.org.uk, brauner@kernel.org, shuah@kernel.org, aarcange@redhat.com, lokeshgidra@google.com, hughd@google.com, mhocko@suse.com, axelrasmussen@google.com, rppt@kernel.org, willy@infradead.org, Liam.Howlett@oracle.com, zhangpeng362@huawei.com, bgeffon@google.com, kaleshsingh@google.com, ngeoffray@google.com, jdduke@google.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v2 2/3] userfaultfd: UFFDIO_REMAP uABI Message-ID: References: <20230923013148.1390521-1-surenb@google.com> <20230923013148.1390521-3-surenb@google.com> <03f95e90-82bd-6ee2-7c0d-d4dc5d3e15ee@redhat.com> MIME-Version: 1.0 In-Reply-To: <03f95e90-82bd-6ee2-7c0d-d4dc5d3e15ee@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 6AE3580015 X-Stat-Signature: o84zipgjkd5tuupzotqwjcetqykrifdt X-HE-Tag: 1695918299-694651 X-HE-Meta: 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 ylWUQkBX WINdXU32MDK9Fzal+DQSHAKYnqZ8OiqJwOOH7AL20Wd2P5pU9Ez/oWJO4UQ1P/H8Lf+uxwK0Gw7Er1CoLt1IwgrSfNquIyL71rVzQzACHrmjAgOTErICDeEMIPfy+VOcGVZoVYBCffKsUu2/TJH9BiR2PJthgN5pRmaS9nKv/iJOqXg1cC/GICa7QWtBCaqOTnOMv/eXMCwixnY4yOTSyA8sA2kN+fad82dMyNahOm3SKL5dqtKYA6n4wav96UhS6hkheYn18pQPzrjQj2H/+oMQsMayAhpqAwMRYElUZfGYg/iYT3c2GsBn07ewTdUdhsNT7JzEA6YViDUILTxgdL2ug3QhmRTj/HJormgOUvxJfZPJw0X6RwTe46zc4n5pTlOOjd+ZS2tlGeH+fxh0555Hsf9dub6PoJ0Tf X-Bogosity: Ham, tests=bogofilter, spamicity=0.067837, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Sep 27, 2023 at 03:29:35PM +0200, David Hildenbrand wrote: > > > + if (!pte_same(*src_pte, orig_src_pte) || > > > + !pte_same(*dst_pte, orig_dst_pte) || > > > + folio_test_large(src_folio) || > > > + folio_estimated_sharers(src_folio) != 1) { > > ^ here you should check PageAnonExclusive. Please get rid of any implicit > explicit/implcit mapcount checks. David, is PageAnon 100% accurate now in the current tree? IOW, can it be possible that the page has total_mapcount==1 but missing AnonExclusive bit in any possible way? Thanks, -- Peter Xu