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Fri, 12 Sep 2025 10:48:25 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id RcKSHnn6w2gcWwAAD6G6ig (envelope-from ); Fri, 12 Sep 2025 10:48:25 +0000 Date: Fri, 12 Sep 2025 11:48:15 +0100 From: Pedro Falcato To: "Roy, Patrick" Cc: "Thomson, Jack" , "Kalyazin, Nikita" , "Cali, Marco" , "derekmn@amazon.co.uk" , Elliot Berman , "willy@infradead.org" , "corbet@lwn.net" , "pbonzini@redhat.com" , "maz@kernel.org" , "oliver.upton@linux.dev" , "joey.gouly@arm.com" , "suzuki.poulose@arm.com" , "yuzenghui@huawei.com" , "catalin.marinas@arm.com" , "will@kernel.org" , "chenhuacai@kernel.org" , "kernel@xen0n.name" , "paul.walmsley@sifive.com" , "palmer@dabbelt.com" , "aou@eecs.berkeley.edu" , "alex@ghiti.fr" , "agordeev@linux.ibm.com" , "gerald.schaefer@linux.ibm.com" , "hca@linux.ibm.com" , "gor@linux.ibm.com" , "borntraeger@linux.ibm.com" , "svens@linux.ibm.com" , "dave.hansen@linux.intel.com" , "luto@kernel.org" , "peterz@infradead.org" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "x86@kernel.org" , "hpa@zytor.com" , "trondmy@kernel.org" , "anna@kernel.org" , "hubcap@omnibond.com" , "martin@omnibond.com" , "viro@zeniv.linux.org.uk" , "brauner@kernel.org" , "jack@suse.cz" , "akpm@linux-foundation.org" , "david@redhat.com" , "lorenzo.stoakes@oracle.com" , "Liam.Howlett@oracle.com" , "vbabka@suse.cz" , "rppt@kernel.org" , "surenb@google.com" , "mhocko@suse.com" , "ast@kernel.org" , "daniel@iogearbox.net" , "andrii@kernel.org" , "martin.lau@linux.dev" , "eddyz87@gmail.com" , "song@kernel.org" , "yonghong.song@linux.dev" , "john.fastabend@gmail.com" , "kpsingh@kernel.org" , "sdf@fomichev.me" , "haoluo@google.com" , "jolsa@kernel.org" , "jgg@ziepe.ca" , "jhubbard@nvidia.com" , "peterx@redhat.com" , "jannh@google.com" , "axelrasmussen@google.com" , "yuanchu@google.com" , "weixugc@google.com" , "hannes@cmpxchg.org" , "zhengqi.arch@bytedance.com" , "shakeel.butt@linux.dev" , "shuah@kernel.org" , "seanjc@google.com" , "linux-fsdevel@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.linux.dev" , "loongarch@lists.linux.dev" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" , "linux-nfs@vger.kernel.org" , "devel@lists.orangefs.org" , "linux-mm@kvack.org" , "bpf@vger.kernel.org" , "linux-kselftest@vger.kernel.org" Subject: Re: [PATCH v6 01/11] filemap: Pass address_space mapping to ->free_folio() Message-ID: <2w22wsqar437lyp3w4bltyoql4ksn3exppkyaia5ogtnt2ttte@6nptj6ed4qnm> References: <20250912091708.17502-1-roypat@amazon.co.uk> <20250912091708.17502-2-roypat@amazon.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250912091708.17502-2-roypat@amazon.co.uk> X-Rspamd-Action: no action X-Stat-Signature: jomnmyjff8dij7wu7e8fmw5gfao3u581 X-Rspam-User: X-Rspamd-Queue-Id: 7A36F160002 X-Rspamd-Server: rspam04 X-HE-Tag: 1757674113-887221 X-HE-Meta: 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 4QyTGq7I 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 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: List-Subscribe: List-Unsubscribe: On Fri, Sep 12, 2025 at 09:17:31AM +0000, Roy, Patrick wrote: > From: Elliot Berman > > When guest_memfd removes memory from the host kernel's direct map, > direct map entries must be restored before the memory is freed again. To > do so, ->free_folio() needs to know whether a gmem folio was direct map > removed in the first place though. While possible to keep track of this > information on each individual folio (e.g. via page flags), direct map > removal is an all-or-nothing property of the entire guest_memfd, so it > is less error prone to just check the flag stored in the gmem inode's > private data. However, by the time ->free_folio() is called, > folio->mapping might be cleared. To still allow access to the address > space from which the folio was just removed, pass it in as an additional > argument to ->free_folio, as the mapping is well-known to all callers. > > Link: https://lore.kernel.org/all/15f665b4-2d33-41ca-ac50-fafe24ade32f@redhat.com/ > Suggested-by: David Hildenbrand > Acked-by: David Hildenbrand > Signed-off-by: Elliot Berman > [patrick: rewrite shortlog for new usecase] > Signed-off-by: Patrick Roy Reviewed-by: Pedro Falcato -- Pedro