[Bug 112125] New: kworker consumes 100% of one CPU core after kernel upgrade from 5.2.14 to 5.3

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=112125

            Bug ID: 112125
           Summary: kworker consumes 100% of one CPU core after kernel
                    upgrade from 5.2.14 to 5.3
           Product: DRI
           Version: unspecified
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: major
          Priority: not set
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: val.kulkov at gmail.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

A kernel upgrade from 5.2.* to 5.3.* results in 100% usage of one of the
available CPU cores. Comparing the output of /proc/interrupts before and after
upgrade reveals that upon such upgrade:

- the number of i915 interrupts increases by a factor of 59,
- the number of local timer interrupts increases by a factor of 24, and
- the number of rescheduling interrupts increases by a factor of 6.

Bisecting kernel from 5.2 to 5.3 identifies commit
6cfe7ec02e854278fb341e62db54d49a2b199c62 as the culprit:
https://github.com/torvalds/linux/commit/6cfe7ec02e854278fb341e62db54d49a2b199c62

Full details are available at
https://bbs.archlinux.org/viewtopic.php?pid=1869944

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