Hi, [ Quoting in full for debian-boot@'s benefit ] Roland Clobus <rclobus@rclobus.nl> (2025-05-19): > Hello maintainers of the kernel, > > The new kernel (6.12.29) has a modified behaviour (compared to > 6.12.27) for the loop device. > > This causes the Debian live images (for sid) to fail to boot. > > The change happened between 20250518T201633Z and 20250519T021902Z, which > matches the upload of 6.12.29 (https://tracker.debian.org/news/1646619/accepted-linux-signed-amd64-612291-source-into-unstable/) > at 20250518T230426Z. > > To reproduce: > * Download the daily live image from https://openqa.debian.net/tests/396941/asset/iso/smallest-build_sid_20250519T021902Z.iso > * Boot into the live image (the first boot option) > * Result: an initramfs shell (instead of a live system) -> FAIL > * Try: `losetup -r /dev/loop1 /run/live/medium/live/filesystem.squashfs` > * Result: `failed to set up loop device: invalid argument` -> FAIL > * Try: `cp /run/live/medium/live/filesystem.squashfs /` > * Try: `losetup -r /dev/loop2 /filesystem.squashfs` > * Result: `loop2: detected capacity change from 0 to 1460312` -> PASS > > It appears that the loopback device cannot be used any more with the mount > /run/live/medium (which is on /dev/sr0). > > I've verified: the md5sum of the squashfs file is OK. > > The newer kernel is not in trixie yet. Skimming over the upstream changes between .27 and .29, maybe this one? loop: Add sanity check for read/write_iter [ Upstream commit f5c84eff634ba003326aa034c414e2a9dcb7c6a7 ] Some file systems do not support read_iter/write_iter, such as selinuxfs in this issue. So before calling them, first confirm that the interface is supported and then call it. It is releavant in that vfs_iter_read/write have the check, and removal of their used caused szybot to be able to hit this issue. Fixes: f2fed441c69b ("loop: stop using vfs_iter__{read,write} for buffered I/O") Reported-by: syzbot+6af973a3b8dfd2faefdc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=6af973a3b8dfd2faefdc Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20250428143626.3318717-1-lizhi.xu@windriver.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> New checks, about the baking file, returning EINVAL… I have no idea about any of this works, but checking something about read and *write*, when we're dealing with /dev/sr0… should an option be added somewhere to be explicit about the source's being read-only? - 184b147b9f7f07577567a80fcc9314f2bd0b0b00 (6.12.y): https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=184b147b9f7f07577567a80fcc9314f2bd0b0b00 - f5c84eff634ba003326aa034c414e2a9dcb7c6a7 (mainline): https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f5c84eff634ba003326aa034c414e2a9dcb7c6a7 Cheers, -- Cyril Brulebois (kibi@debian.org) <https://debamax.com/> D-I release manager -- Release team member -- Freelance Consultant
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