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Fri, 17 Apr 2026 13:34:02 -0700 (PDT) Date: Fri, 17 Apr 2026 20:34:00 +0000 From: Pasha Tatashin To: luca.boccassi@gmail.com Cc: kexec@lists.infradead.org, linux-mm@kvack.org, graf@amazon.com, rppt@kernel.org, pratyush@kernel.org, brauner@kernel.org Subject: Re: [PATCH v2] liveupdate: add LUO_SESSION_MAGIC magic inode type Message-ID: <3rtwn7lkj5icexyammer5limslchbkm4xdgynp5llbt3wwybnp@ikjv5si2xodg> References: <20260417094426.1556849-1-luca.boccassi@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260417094426.1556849-1-luca.boccassi@gmail.com> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 9A789120006 X-Stat-Signature: qitrouq4qnwp6j79yoftjsymi73ntagw X-Rspam-User: X-HE-Tag: 1776458043-782542 X-HE-Meta: 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 /JZ9m1nY AGPhuyr5cDNpIzTUPkAoAshbEFWKD54y7+qBm455sio16CSJnkNRcngwFLRY+fJmAOSSuvUOJtvXhYXttFirUa6s2bkysjnZ0T3BUOOJw1Mxxz5yjn0y3idXR/hrBTFwojGuNvgDrtwXjlpVnQM/Pf7edm1b9Y5Iv580gHOP1OjLNKxNVVVnyuGGbBM6ktw/pkLau7cT1kgZ97/rijN0dgwSkSdB823ficHvKJKK0YWbBKbPMiYE4D9AOSRSr640fH749RN0YCFtTTiy8ZjfRVX0pLei1fTVSjaju9JCU3is20nYoX1pIh1YKwM/1SrVuHIHO/S5mLMzKfm97L1RWcEtOEhqiDBuJ/HfHLiZdFxtHmX7S7pT87x5ojGrKIuKDB4ovEyhVCNyTcU1OzorTP4U6n8QuC5orIhbr8Fkpte+hbSRMi6prsbz5aJRCrb5qr05YgnwQJt5vL8VJQuOP9MQH8iL5k3EBh0iU Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 04-17 10:44, luca.boccassi@gmail.com wrote: > From: Luca Boccassi > > In userspace when managing LUO sessions we want to be able to identify > a FD as a LUO session, in order to be able to do the special handling > that they require in order to function as intended on kexec. > > Currently this requires scraping procfs and doing string matching on > the prefix of the dname, which is not an ideal interface. > > Add a singleton inode type with a magic value, so that we can > programmatically identify a fd as a LUO session via fstat(). Hi Luca, The patch looks good to me, but please add a self-test to selftests/liveupdate/liveupdate.c to verify that the fstat interface works as expected. Pasha