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Wong" , "Namhyung Kim" , "Ingo Molnar" , "Andrei Vagin" , "Alexander Mikhalitsyn" Subject: Re: [PATCH v2 1/1] statmount: accept fd as a parameter From: "Bhavik Sachdev" To: "Miklos Szeredi" X-Mailer: aerc 0.20.1 References: <20251011124753.1820802-1-b.sachdev1904@gmail.com> <20251011124753.1820802-2-b.sachdev1904@gmail.com> In-Reply-To: On Wed Oct 22, 2025 at 10:02 PM IST, Miklos Szeredi wrote: > What's wrong with statx + statmount? We would like to get mountinfo for "unmounted" mounts i.e we have an fd on a mount that has been unmounted with MNT_DETACH. statmount() does not work on such mounts (with the mnt_id_unique from statx), since they have no mount namespace. These mounts also don't show up in proc. v1 of this patch tried a different approach by introducing a new mount namespace for "unmounted" mounts, which had a bunch of complications [1]. The cover letter for this patch also has more information [2]. We want to support checkpoint/restore of such fds with CRIU [3]. [1]: https://lore.kernel.org/all/20251006-erlesen-anlagen-9af59899a969@brau= ner/ [2]: https://lore.kernel.org/all/20251011124753.1820802-1-b.sachdev1904@gma= il.com/ [3]: https://github.com/checkpoint-restore/criu/pull/2754 Kind regards, Bhavik