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[34.127.75.64]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ae6e973ac6sm1327770a91.11.2026.10.28.16.09.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Oct 2026 16:09:13 -0700 (PDT) Date: Wed, 28 Oct 2026 23:09:09 +0000 From: David Matlack To: Pasha Tatashin Cc: kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Alexander Graf , Andrew Morton , Baolin Wang , Christian Brauner , David Hildenbrand , Hugh Dickins , Jonathan Corbet , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Pratyush Yadav , Randy Dunlap , Samiullah Khawaja , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka Subject: Re: [PATCH v2 07/10] mm/shmem_luo: Retrieve tmpfs files onto a tmpfs mount chosen by userspace Message-ID: References: <20261022225035.377445-1-dmatlack@google.com> <20261022225035.377445-8-dmatlack@google.com> <179322496574.1894369.544573858973645958.b4-review@b4> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <179322496574.1894369.544573858973645958.b4-review@b4> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 0D7414000D X-Stat-Signature: ffahzefhhzsgrkcs5zi89o6zr7rtgr65 X-Rspam-User: X-Spam-Status: No, score=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1793228957-915862 X-HE-Meta: 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 eC40KKls ZLMu7enlStpapN0UncRxSDcZqIjqH5hdtcM3qwxfvpLeadp1AMkUoUbQ3e9BI7w8yWPVkCYxnV40GnSOkgsPL/guTSJEC2/DeAOe4DIBVkQ6ixv0X2C4Q/eYtWmmkE4c7focHbzyTWcejS8/l9HPwzw9Id8P+BCahSUo5y9pIBvmgSWLsvNs75m0+V2vGOVzsxj3dtaMNNqmGtCRm1GW3iweMEq6QLFUw1jrVDYqtZ4USwZtekcwmlhNbNjLyiQYLL79wqH8ClL8jPQVo1Xd9rw/EITLZaIhTQ2rpEN31umQcoYLzkTzAo+K/Gv7TBBKscD8b31Wm6TzBMAMwF7lsd76gafpw/PuSeiFNocZTvKlk8j+j3o0MxAR/K2raRw4RJsB6b/g4Zg/Z79dmEXOLYO5ImDp6G1q0Empv Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 2026-10-28 06:02 PM, Pasha Tatashin wrote: > > +/* > > + * Whether @inode is on the internal shmem mount, which is used by > > + * shmem_file_setup() and thus by memfd_create(). > > + */ > > +bool shmem_inode_on_internal_mount(const struct inode *inode) > > +{ > > + return inode->i_sb == shm_mnt->mnt_sb; > > +} > > Please fix the warning reported by kernel test robot. Will do. The prototype for shmem_inode_on_internal_mount() is in mm/internal.h, which mm/shmem.c only includes if CONFIG_SHMEM=y, but the robot was building without CONFIG_SHMEM. I've moved the definition of this function into CONFIG_SHMEM in v3 to fix this. > Looking at this together with Pratyush's mapping-freeze series ([PATCH > 0/3] mm: allow freezing mappings), I think we should extend the mapping > freeze lifecycle from preserve() -> retrieve() to preserve() -> > finish(). > > When retrieve() returns an fd, its mapping should still come out frozen > and only become fully user-owned/mutable once a successful session > finish() happens. That keeps the index -> folio mapping invariant across > the entire live update until every fd in the session (e.g. vmfd, > iommufd, vfiofd that depend on the memfd) has been retrieved, passed > can_finish(), and been finalized together in finish(). > > (Doesn't have to block this series, we can do it on top or as part of > Pratyush's AS_FROZEN series.), but I think we must fix it either here or > there.) Ok that sounds reasonable. Should we do that as part of Pratyush's series then? Pratyuh's series replaces shmem_freeze() with mapping_set_frozen(), so retrieve() would freeze the new file and finish() would unfreeze it. That should work the same for memfds and tmpfs files.. BTW, this tmpfs series does a lot of renames and code motion so it conflicts with Pratyush's series. How should we order these?