Bug 2429501

Summary: grub2-install fails on Rawhide BIOS with XFS: grub_fs_probe unknown filesystem
Product: [Fedora] Fedora Reporter: Xiaofeng Wang <xiaofwan>
Component: grub2Assignee: Nicolas Frayer <nfrayer>
Status: CLOSED RAWHIDE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: unspecified    
Version: rawhideCC: awilliam, bgoncalv, bugzilla, kkoukiou, lkundrak, lsandova, miabbott, mlewando, nfrayer, pjones, robatino
Target Milestone: ---Keywords: TestBlocker
Target Release: ---   
Hardware: Unspecified   
OS: Linux   
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Last Closed: 2026-01-22 16:51:31 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2362357    
Attachments:
Description Flags
xfs error during grub2-install
none
tail of verbose grub2-install command none

Description Xiaofeng Wang 2026-01-14 02:54:13 UTC
On Fedora Rawhide, grub2-install fails in BIOS mode when the root filesystem is XFS, causing bootc and Anaconda installations to fail with:

grub_fs_probe: unknown filesystem

This is a regression compared to Fedora 43. The same workflow succeeds when using btrfs or when booting in UEFI mode.

This breaks:
bootc install to-disk
Anaconda installer (BootloaderInstallationError)

Environment:
Fedora Rawhide (current)
grub2 >= 2.12-49.fc44 (Rawhide)
Boot mode: BIOS (i386-pc)
Root filesystem: XFS
Target disk: loopback device (/dev/loop0)
Tooling: bootc + bootupd

Reproducible: Always

Steps to Reproduce:
bootc install to-disk \
  --disable-selinux \
  --via-loopback \
  --filesystem xfs \
  --source-imgref docker://quay.io/centos-bootc/centos-bootc:stream10 \
  ./disk.img

bootc automatically enables --generic-image.

Partitioning created by bootc:

/dev/loop0p1  BIOS boot      1 MiB
/dev/loop0p2  EFI System   512 MiB (vfat)
/dev/loop0p3  Linux root   9.5 GiB (XFS)

Filesystem creation:

mkfs.xfs /dev/loop0p3
mkfs.fat /dev/loop0p2

Actual Results:
Bootloader installation fails:
Installing for i386-pc platform.
/usr/sbin/grub2-install: error: ../grub-core/kern/fs.c:grub_fs_probe:123:unknown filesystem.


bootc then aborts:
error: boot data installation failed: installing component BIOS
Failed to run "/usr/sbin/grub2-install" ... "/dev/loop0"


Full command:
grub2-install --target i386-pc \
  --boot-directory /run/bootc/mounts/rootfs/boot \
  --modules "mdraid1x part_gpt" \
  /dev/loop0


Final failure:
BootloaderInstallationError / Installing bootloader failed


Expected Results:
Installation should succeed and GRUB should be installed to the disk as it does on early Fedora rawhide or Fedora 43.

Additional Information:
This appears to be caused by recent GRUB changes in Rawhide (possibly related to stricter filesystem probing introduced by the GRUB OOM-fix series).

Possibly related to Bug 2427945 (GRUB regression in Rawhide), but this issue affects BIOS + XFS during installation rather than UEFI boot at runtime.

Comment 1 Marta Lewandowska 2026-01-14 13:11:06 UTC
Created attachment 2122138 [details]
xfs error during grub2-install

Comment 2 Marta Lewandowska 2026-01-14 13:11:36 UTC
Created attachment 2122139 [details]
tail of verbose grub2-install command

Comment 3 Marta Lewandowska 2026-01-15 10:05:40 UTC
Nicolas identified an upstream patch that fixes this, based on my testing. It will get to fedora soon.
https://cgit.git.savannah.gnu.org/cgit/grub.git/commit/?id=1ed2628b560cedac7fd1a696985ab85b24541a8e

Comment 4 Marta Lewandowska 2026-01-15 16:36:56 UTC
*** Bug 2430018 has been marked as a duplicate of this bug. ***

Comment 5 Marta Lewandowska 2026-01-19 13:30:21 UTC
*** Bug 2430281 has been marked as a duplicate of this bug. ***

Comment 6 Chris Murphy 2026-01-19 16:39:52 UTC
When I click on attachments in this bug I get "Sorry, you are not authorized to access attachment". I'd like to understand what feature of XFS grub-install is failing on.

Comment 7 Marta Lewandowska 2026-01-19 16:50:19 UTC
Created attachment 2122761 [details]
xfs error during grub2-install

Comment 8 Marta Lewandowska 2026-01-19 16:51:15 UTC
Created attachment 2122762 [details]
tail of verbose grub2-install command

Comment 9 Marta Lewandowska 2026-01-19 16:51:54 UTC
sorry, Chris. You should be able to access the attachments now.

Comment 10 Chris Murphy 2026-01-19 16:58:43 UTC
OK I'm seeing it in https://bugzilla.redhat.com/show_bug.cgi?id=2430281#c11

Looks like xfsprogs 6.18 adds XFS_SB_FEAT_INCOMPAT_PARENT flag at mkfs time. And that is one of the feature flag added by https://cgit.git.savannah.gnu.org/cgit/grub.git/commit/?id=1ed2628b560cedac7fd1a696985ab85b24541a8e

Comment 11 Adam Williamson 2026-01-19 20:34:38 UTC
Yes, also XFS_SB_FEAT_INCOMPAT_EXCHRANGE , added to grub in the same commit.

Comment 12 Adam Williamson 2026-01-22 00:21:13 UTC
Can we please have this fixed soon? It's extremely disruptive to testing; literally over 100 openQA compose tests fail because of this bug (every install that runs with the Server profile).

Comment 13 Nicolas Frayer 2026-01-22 08:02:55 UTC
This update should contain the fix: https://bodhi.fedoraproject.org/updates/FEDORA-2026-384dcb944e

Comment 14 Adam Williamson 2026-01-22 16:51:16 UTC
Awesome, yes, looks like it does. Now I can see all the other bugs that were hiding behind it!

Comment 15 Katerina Koukiou 2026-01-26 12:44:40 UTC
With grub2-common-1:2.12-52.fc44.noarch I still see this almost same error in the image refreshes in anaconda-webui CI.


    Jan 26 12:26:46 ibm-p8-kvm-03-guest-02.virt.pnr.lab.eng.rdu2.redhat.com org.fedoraproject.Anaconda.Modules.Storage[6490]: INFO:program:Running in chroot '/mnt/sysroot'... gen_grub_cfgstub /boot/grub2 /boot/efi/EFI/fedora
    org.fedoraproject.Anaconda.Modules.Storage[6490]: INFO:program:grub2-probe: error: ../grub-core/kern/fs.c:grub_fs_probe:123:unknown filesystem.
    Jan 26 12:26:46 ibm-p8-kvm-03-guest-02.virt.pnr.lab.eng.rdu2.redhat.com org.fedoraproject.Anaconda.Modules.Storage[6490]: DEBUG:program:Return code of gen_grub_cfgstub: 1

Comment 16 Nicolas Frayer 2026-01-26 13:26:22 UTC
Can you please point me to the rawhide image you are testing with ?

Comment 18 Katerina Koukiou 2026-01-26 13:58:37 UTC
Sorry, comment above is inaccurate:
The CI test that we hit the failures against ran on the image with this checksum: SHA256 (Fedora-Server-netinst-x86_64-Rawhide-20260126.n.0.iso) = b2971bcc2cb89e2a607891aa76cfa6211148e5995e696ff13cf9467f86398e87