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[34.127.79.33]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ed090a1475sm11919255ad.41.2026.11.04.14.32.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Nov 2026 14:32:20 -0800 (PST) Date: Wed, 4 Nov 2026 22:32:15 +0000 From: David Matlack To: Pratyush Yadav 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 , Pasha Tatashin , Randy Dunlap , Samiullah Khawaja , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka Subject: Re: [PATCH v3 08/10] mm/shmem_luo: Allow preserving tmpfs files that are still linked Message-ID: References: <20261103010216.3447716-1-dmatlack@google.com> <20261103010216.3447716-9-dmatlack@google.com> <2vxza4nok0ji.fsf@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2vxza4nok0ji.fsf@kernel.org> X-Stat-Signature: n9wpm6thyhzsiimyyyncbro6xp493dqt X-Rspamd-Server: rspam01 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-Rspamd-Queue-Id: 9B5C7120006 X-HE-Tag: 1793831542-428974 X-HE-Meta: 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 8BmF0Aoy ero7JALfYX5JDBx3/bUmVb5RnVHq2O5n0yxeCRbv94OmEmpdJBB1dB738FaKthFRYbsU3ItHBDYrBnjdKnpJOhbX4YBlncL1YmKV0ShN4po2R6R386CWHsIonYoJJrX5sY9mzZx1ykVJA3sziKle7txgz2vwirvMvJGsEi1PCL9R6a04sn6MlVgA3dmU8FXaF+E9S8l08qthIjdpnix7nJwvLA2rbnfgHkz5sCxELoFTzsoTsOVJ7kwv0wPhRC0JeaMUlITud176IIiKYyv4tdDIyYlNxGkO8fUOVi7xJoz73TiAEze/cCGnMGV2ZPTijuR/Talgw6XGzf7WdHu/MJ/BtauGiiyGGCVQmCTKRkvrFP4JIDODEjhVTsy8IIXhqJzcaNFbb617ycpcCKnTP5vBvZ9rUe7oYI4mS 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 2026-11-04 05:45 PM, Pratyush Yadav wrote: [...] > > + * Preserving a file requires it to be opened for reading, since the retrieved > > + * file can be read. It also requires permission to write to the file, since > > + * preserving it affects all of its users, as described below. But the file > > + * doesn't need to be opened for writing. For example, a binary that is being > > + * executed can be preserved through a read-only file descriptor. The owner of > > Why are you talking about preserving binaries being executed? Seems > oddly specific. I didn't know that was a use case we cared about. It's the reason the check looks at permission on the inode instead of requiring an fd opened for writing: a running binary can't be opened for writing (-ETXTBSY), so requiring a writable fd would make it impossible to preserve. Preserving binaries is a use case we care about, e.g. to carry over the binaries of services across a Live Update. I'll keep the comment shorter and more general in v4.