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Fri, 17 Apr 2026 13:59:37 -0700 (PDT) MIME-Version: 1.0 References: <20260417204039.1827319-1-luca.boccassi@gmail.com> <547dc4f7xmafywo7jfeuordj5uwaq5lq4zfdupvswxy5yn5osj@v67ia535jnfw> In-Reply-To: <547dc4f7xmafywo7jfeuordj5uwaq5lq4zfdupvswxy5yn5osj@v67ia535jnfw> From: Luca Boccassi Date: Fri, 17 Apr 2026 21:59:23 +0100 X-Gm-Features: AQROBzDPb8w6RKJJ7naC7qwRolTzXugdDA1zS20bjZ619PpPhYtV0_RCHxk_70M Message-ID: Subject: Re: [PATCH v3] 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, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 18E4F40008 X-Rspamd-Server: rspam07 X-Stat-Signature: u6dicbbmynwrhhy9io9qdwnyuh864cgk X-Rspam-User: X-HE-Tag: 1776459577-613670 X-HE-Meta: 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 0idbru7u 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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 21:53, Pasha Tatashin wrote: > > On 04-17 21:40, 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(). > > > > Signed-off-by: Luca Boccassi > > --- > > This was requested by Lennart and Christian when discussing integration > > with systemd for LUO management. > > > > v2: apply one fix from bot review about cleanup on error path: > > https://sashiko.dev/#/patchset/20260415184536.1155220-1-luca.boccassi%40gmail.com > > the other comments are invalid: luo is not a kmod, and the write hooks are not set up > > v3: add test case to liveupdate selftest > > This should be split into two patches, also please CC: > linux-kernel@vger.kernel.org ... > Reverse-christmast-tree order please. Done with v4, thanks