Bug 2226558 - bfq + losetup: loop devices disappear
Summary: bfq + losetup: loop devices disappear
Keywords:
Status: NEW
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: rawhide
Hardware: Unspecified
OS: Linux
unspecified
high
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2023-07-25 23:56 UTC by Ed Santiago
Modified: 2023-07-26 00:00 UTC (History)
16 users (show)

Fixed In Version:
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Attachments (Terms of Use)
reproducer for bfq-losetup weirdness (830 bytes, text/plain)
2023-07-25 23:58 UTC, Ed Santiago 		no flags Details
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Description Ed Santiago 2023-07-25 23:56:46 UTC 
This is bizarre and I'm not 100% sure I have a true reproducer (see TBD attachment).

Basically: run losetup, use bfq scheduler on it, and future losetup commands cause "losetup -l" to emit no output.

Confirmed on kernels:
  6.4.0-0.rc7.20230623git8a28a0b6f1a1.57.fc39.x86_64
  6.5.0-0.rc2.20230721gitf7e3a1bafdea.20.fc39.x86_64

Reproducible: Always
Comment 1 Ed Santiago 2023-07-25 23:58:10 UTC 
Created attachment 1979984 [details]
reproducer for bfq-losetup weirdness
Comment 2 Ed Santiago 2023-07-26 00:00:46 UTC 
Originally found via:

  # dnf install podman-tests
  # bats /usr/share/podman/test/system/180-blkio.bats
  [works the first time, but gets skipped because /sys/fs/cgroup/blkio/system.slice/blkio.bfq.weight_device is missing ]
  # !!
  [ this time it fails because 'losetup -l' emits no output]
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