On Tue, 12 Jan 2021 22:18:55 +0000, Will Deacon wrote:

This reverts commit 367c820ef08082e68df8a3bc12e62393af21e4b5.

lockup_detector_init() makes heavy use of per-cpu variables and must be
called with preemption disabled. Usually, it's handled early during boot
in kernel_ionit_freeable(), before SMP has been initialised.

Since we do not know whether or not our PMU interrupt can be signalled
as an NMI until considerably later in the boot process, the Arm PMU
driver attempts to re-initialise the lockup detector off the back of a
device_initcall(). Unfortunately, this is called from preemptible
context and results in the following splat:

[...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] Revert "arm64: Enable perf events based hard lockup detector"
      https://git.kernel.org/arm64/c/b90d72a6bfdb

-- 
Catalin


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