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b=PiaYdB/6a+Mmpo8s7JnI43D9v3kTtg0YWl0Ywx4jNX47uPO7NvVs5caHtJ8loMX40 QOP77tYBVIbUSxtHmAxPxkndq0Ai65F3GhP+7CBZ5aFRfi2gfdD7PuJFZZzeUg1npd UcDZQjCzpEmieEiD/2DcrBZyExhMwVlRaDykIK4JIJESnesyofEMn8AaLYuc7PyMEy HAuoPdFF4llpLEBFvlYKjSeki9rMcMlMVsDdGmZsspdA/dsPzZmVwzwf0KMORHs2b7 WjjyWbBfckfkdfVZh7b1KDCNp7xVMk3R9vi8RgWDFZFjrX5mEQRUf31A/ro5cUvLnS CUtQpY8UDsWhw== Date: Tue, 21 Apr 2026 13:33:43 +0300 From: Mike Rapoport To: luca.boccassi@gmail.com Cc: kexec@lists.infradead.org, linux-mm@kvack.org, graf@amazon.com, pasha.tatashin@soleen.com, pratyush@kernel.org, brauner@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 3/6] liveupdate: add LUO_SESSION_MAGIC magic inode type Message-ID: References: <20260420141741.2688371-1-luca.boccassi@gmail.com> <20260420141741.2688371-4-luca.boccassi@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260420141741.2688371-4-luca.boccassi@gmail.com> X-Rspamd-Queue-Id: B3FE740006 X-Rspamd-Server: rspam07 X-Stat-Signature: 4udhhuhxwupzy5ceoxc4piptpnat1qcx X-Rspam-User: X-HE-Tag: 1776767630-79555 X-HE-Meta: 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 j8lhSSf+ eVXkD9E1vjjz695a/3BMOtdn2euXd0SyljWPD+dNVgfbTqhF9Mru7jbK3Aml32zI1r1rTgAShEAwBKl8mEWf3dIZInfC09nKp9/fIptkfn/3lhwKjmzo+ooVnsIg/yP80YsFg7nIoFAVYcRuzCLpskhR9REvHp+qLhX/UaWcB15+jjWgq/yVGmR57uagRbL0X4dvcpoIjqsWbVls0T+eiKbmZMDUayLM/F1OimxyKqB5vFcI8Kq/IR07y66ngCOkjZeC9GA6fBcmi2yed3uXpj+PSOVI1y6hsTiq1WqHH6phZOfaLfRvASsS8e5GI0jd3NBpSOT5PR1YAqArltYd2SoLt0nTEG1YNLel1hhgRibXxncNVerCaybIfMPrngYG5rWHwhalTuWzD/qUL1f1zvimRjZDpoyc9ciCu9QWsdNW76HEDKfsJVbKLMAFdvtx1Rd8ZFkLRKPC5oGUkDSgVp4gtCGsJHRy2+oJJ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 20, 2026 at 03:15:11PM +0100, 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 fstatfs(). > > Signed-off-by: Luca Boccassi > Reviewed-by: Pasha Tatashin > --- > include/uapi/linux/magic.h | 1 + > kernel/liveupdate/luo_core.c | 10 +++- > kernel/liveupdate/luo_internal.h | 2 + > kernel/liveupdate/luo_session.c | 91 ++++++++++++++++++++++++++++++-- > 4 files changed, 98 insertions(+), 6 deletions(-) > > diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h > index 4f2da935a76c..4f51005522ff 100644 > --- a/include/uapi/linux/magic.h > +++ b/include/uapi/linux/magic.h > @@ -105,5 +105,6 @@ > #define PID_FS_MAGIC 0x50494446 /* "PIDF" */ > #define GUEST_MEMFD_MAGIC 0x474d454d /* "GMEM" */ > #define NULL_FS_MAGIC 0x4E554C4C /* "NULL" */ > +#define LUO_SESSION_MAGIC 0x4c554f53 /* "LUOS" */ > > #endif /* __LINUX_MAGIC_H__ */ > diff --git a/kernel/liveupdate/luo_core.c b/kernel/liveupdate/luo_core.c > index dda7bb57d421..f1a63ebe4fa4 100644 > --- a/kernel/liveupdate/luo_core.c > +++ b/kernel/liveupdate/luo_core.c > @@ -197,9 +197,17 @@ static int __init luo_late_startup(void) > if (!liveupdate_enabled()) > return 0; > > + err = luo_session_fs_init(); > + if (err) { > + luo_global.enabled = false; Please use goto here and on luo_fdt_setup() failure to handle cleanup on error. Other than that Acked-by: Mike Rapoport (Microsoft) > + return err; > + } > + > err = luo_fdt_setup(); > - if (err) > + if (err) { > + luo_session_fs_cleanup(); > luo_global.enabled = false; > + } > > return err; > } -- Sincerely yours, Mike.