[6.12.y regression] loosetup: failed to set up loop device: Invalid argument after 184b147b9f7f ("loop: Add sanity check for read/write_iter")
Hi
In Debian Roland Clobus reported a regression with setting up loop devices from a backing squashfs file lying on read-only mounted target directory from a iso.
The original report is at: https://bugs.debian.org/1106070
Quoting the report:
On Mon, May 19, 2025 at 12:15:10PM +0200, Roland Clobus wrote:
Package: linux-image-6.12.29-amd64 Version: 6.12.29-1 Severity: important X-Debbugs-Cc: debian-amd64@lists.debian.org User: debian-amd64@lists.debian.org Usertags: amd64 X-Debbugs-Cc: phil@hands.com User: debian-qa@lists.debian.org Usertags: openqa X-Debbugs-Cc: debian-boot
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-s...) at 20250518T230426Z.
To reproduce:
- Download the daily live image from https://openqa.debian.net/tests/396941/asset/iso/smallest-build_sid_20250519...
- 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.
With kind regards, Roland Clobus
A short reproducer is as follows:
iso="netinst.iso" url="https://openqa.debian.net/tests/396941/asset/iso/smallest-build_sid_20250519..." if [ ! -e "${iso}" ]; then wget "${url}" -O "${iso}" fi mountdir="$(mktemp -d)" mount -v "./${iso}" "${mountdir}" losetup -v -r -f "${mountdir}/live/filesystem.squashfs" loosetup -l
resulting in:
mount: /tmp/tmp.HgbNe7ek3h: WARNING: source write-protected, mounted read-only. mount: /dev/loop0 mounted on /tmp/tmp.HgbNe7ek3h. losetup: /tmp/tmp.HgbNe7ek3h/live/filesystem.squashfs: failed to set up loop device: Invalid argument NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC /dev/loop0 0 0 1 0 /root/netinst.iso 0 512
Reverting 184b147b9f7f ("loop: Add sanity check for read/write_iter") on top of 6.12.29 fixes the issue:
mount: /tmp/tmp.ACkkdCdYvB: WARNING: source write-protected, mounted read-only. mount: /dev/loop0 mounted on /tmp/tmp.ACkkdCdYvB. NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC /dev/loop1 0 0 0 1 /tmp/tmp.ACkkdCdYvB/live/filesystem.squashfs 0 512 /dev/loop0 0 0 1 0 /root/netinst.iso 0 512
For completeness, netinst.iso is a iso9660 fstype with mount options "ro,relatime,nojoliet,check=s,map=n,blocksize=2048,iocharset=utf8".
#regzbot introduced: 184b147b9f7f #regzbot link: https://bugs.debian.org/1106070
Regards, Salvatore
On Tue, May 20, 2025 at 07:57:31AM +0200, Salvatore Bonaccorso wrote:
Hi
In Debian Roland Clobus reported a regression with setting up loop devices from a backing squashfs file lying on read-only mounted target directory from a iso.
The original report is at: https://bugs.debian.org/1106070
Quoting the report:
On Mon, May 19, 2025 at 12:15:10PM +0200, Roland Clobus wrote:
Package: linux-image-6.12.29-amd64 Version: 6.12.29-1 Severity: important X-Debbugs-Cc: debian-amd64@lists.debian.org User: debian-amd64@lists.debian.org Usertags: amd64 X-Debbugs-Cc: phil@hands.com User: debian-qa@lists.debian.org Usertags: openqa X-Debbugs-Cc: debian-boot
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-s...) at 20250518T230426Z.
To reproduce:
- Download the daily live image from https://openqa.debian.net/tests/396941/asset/iso/smallest-build_sid_20250519...
- 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.
With kind regards, Roland Clobus
A short reproducer is as follows:
iso="netinst.iso" url="https://openqa.debian.net/tests/396941/asset/iso/smallest-build_sid_20250519..." if [ ! -e "${iso}" ]; then wget "${url}" -O "${iso}" fi mountdir="$(mktemp -d)" mount -v "./${iso}" "${mountdir}" losetup -v -r -f "${mountdir}/live/filesystem.squashfs" loosetup -l
resulting in:
mount: /tmp/tmp.HgbNe7ek3h: WARNING: source write-protected, mounted read-only. mount: /dev/loop0 mounted on /tmp/tmp.HgbNe7ek3h. losetup: /tmp/tmp.HgbNe7ek3h/live/filesystem.squashfs: failed to set up loop device: Invalid argument NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC /dev/loop0 0 0 1 0 /root/netinst.iso 0 512
Reverting 184b147b9f7f ("loop: Add sanity check for read/write_iter") on top of 6.12.29 fixes the issue:
mount: /tmp/tmp.ACkkdCdYvB: WARNING: source write-protected, mounted read-only. mount: /dev/loop0 mounted on /tmp/tmp.ACkkdCdYvB. NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC /dev/loop1 0 0 0 1 /tmp/tmp.ACkkdCdYvB/live/filesystem.squashfs 0 512 /dev/loop0 0 0 1 0 /root/netinst.iso 0 512
For completeness, netinst.iso is a iso9660 fstype with mount options "ro,relatime,nojoliet,check=s,map=n,blocksize=2048,iocharset=utf8".
#regzbot introduced: 184b147b9f7f #regzbot link: https://bugs.debian.org/1106070
Just tested: The regression exists as well in 6.15-rc7 so it is not specific to the stable 6.12.y update.
Regards, Salvatore
Salvatore Bonaccorso carnil@debian.org on Tue, 2025/05/20 07:57:
In Debian Roland Clobus reported a regression with setting up loop devices from a backing squashfs file lying on read-only mounted target directory from a iso.
The original report is at: https://bugs.debian.org/1106070
We are suffering the same for Arch Linux. Already reported here:
https://lore.kernel.org/all/20250519175640.2fcac001@leda.eworm.net/
H Christian,
On Tue, May 20, 2025 at 08:34:38AM +0200, Christian Hesse wrote:
Salvatore Bonaccorso carnil@debian.org on Tue, 2025/05/20 07:57:
In Debian Roland Clobus reported a regression with setting up loop devices from a backing squashfs file lying on read-only mounted target directory from a iso.
The original report is at: https://bugs.debian.org/1106070
We are suffering the same for Arch Linux. Already reported here:
https://lore.kernel.org/all/20250519175640.2fcac001@leda.eworm.net/
Sorry missed that one! Ack, so let's continue in that thread (worth looping in the regressions list though?)
Regards, Salvatore
Fixed here:
https://git.kernel.dk/cgit/linux/commit/?h=block-6.15&id=355341e4359b2d5...
and will land upstream this week.
linux-stable-mirror@lists.linaro.org
-
Christian Hesse -
Jens Axboe -
Salvatore Bonaccorso