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Fri, 17 Apr 2026 13:41:17 -0700 (PDT) MIME-Version: 1.0 References: <20260417094426.1556849-1-luca.boccassi@gmail.com> <3rtwn7lkj5icexyammer5limslchbkm4xdgynp5llbt3wwybnp@ikjv5si2xodg> In-Reply-To: <3rtwn7lkj5icexyammer5limslchbkm4xdgynp5llbt3wwybnp@ikjv5si2xodg> From: Luca Boccassi Date: Fri, 17 Apr 2026 21:41:06 +0100 X-Gm-Features: AQROBzCSC3rE7AP0-H4hL0tA9NAIE5JD2R9rjoGlXVxZSGuKx95-rERAc1LspiI Message-ID: Subject: Re: [PATCH v2] liveupdate: add LUO_SESSION_MAGIC magic inode type To: Pasha Tatashin Cc: kexec@lists.infradead.org, linux-mm@kvack.org, graf@amazon.com, rppt@kernel.org, pratyush@kernel.org, brauner@kernel.org Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: dwqor4hm5nqa8fckk8k8wqdwfp16n4as X-Rspamd-Queue-Id: 4747040002 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1776458478-60737 X-HE-Meta: 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 rWgQKjMy 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 17 Apr 2026 at 21:34, Pasha Tatashin wrote: > > 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. Sure thing, added and sent v3