[Bug 216007] New: XFS hangs in iowait when extracting large number of files

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=216007

            Bug ID: 216007
           Summary: XFS hangs in iowait when extracting large number of
                    files
           Product: File System
           Version: 2.5
    Kernel Version: 5.15.32
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: XFS
          Assignee: filesystem_xfs@kernel-bugs.kernel.org
          Reporter: bugzkernelorg8392@araxon.sk
        Regression: No

Created attachment 301008
  --> https://bugzilla.kernel.org/attachment.cgi?id=301008&action=edit
output from dmesg after echo w > /proc/sysrq-trigger

Overview:

When I try to extract an uncompressed tar archive (2.6 milion files, 760.3 GiB
in size) on newly created (empty) XFS file system, after first low tens of
gigabytes extracted the process hangs in iowait indefinitely. One CPU core is
100% occupied with iowait, the other CPU core is idle (on 2-core Intel Celeron
G1610T).

I have kernel compiled with my .config file. When I try this with a more
"standard" kernel, the problem is not reproducible.

Steps to Reproduce:

1) compile the kernel with the attached .config

2) reboot with this kernel

3) create a new XFS filesystem on a spare drive (just mkfs.xfs -f <dev>)

4) mount this new file system

5) try to extract large amount of data there

Actual results:

After 20-40 GiB written, the process hangs in iowait indefinitely, never
finishing the archive extraction.

Expected Results:

Archive extraction continues smoothly until done.

Build Date & Hardware:

2022-05-01 on HP ProLiant MicroServer Gen8, 4GB ECC RAM

Additional Information:

No other filesystem tested with the same archive on the same hardware before or
after this (ext2, ext3, ext4, reiserfs3, jfs, nilfs2, f2fs, btrfs, zfs) has
shown this behavior. When I downgraded the kernel to 5.10.109, the XFS started
working again. Kernel versions higher than 5.15 seem to be affected, I tried
5.17.1, 5.17.6 and 5.18.0-rc7, they all hang up after a few minutes.

No error is reported to the system log or to dmesg when the process hangs. No
error shows on stdout or stderr of the tar process either.

This is not a SMR problem. None of the disks present in the test setup are SMR.
All are CMR, and while they certainly are not brand new, they are all in good
working condition.

Attached is the dmesg output after issuing this command:

echo w > /proc/sysrq-trigger

More could be found here: https://forums.gentoo.org/viewtopic-p-8709116.html

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