On Tue, 25 Jan 2022 00:39:28 +1000, Nicholas Piggin wrote:

The decrementer exception can fail to be cleared when the interrupt
returns in the case where the decrementer wraps with the next timer
still beyond decrementer_max. This results in a decrementer interrupt
storm. This is triggerable with small decrementer system with hard
and soft watchdogs disabled.

Fix this by always programming the decrementer if there was no timer.

[...]

Patch 1 applied to powerpc/fixes.

[1/3] powerpc/64s/interrupt: Fix decrementer storm
      https://git.kernel.org/powerpc/c/8defc2a5dd8f4c0cb19ecbaca8d3e89ab98524da

cheers