[PATCH v3 0/2] Reduce CPU consumption after panic

[carlos.bilbao@kernel.org]

From: Carlos Bilbao <carlos.bilbao@kernel.org>

Provide a priority-based mechanism to set the behavior of the kernel at
the post-panic stage -- the current default is a waste of CPU except for
cases with console that generate insightful output.

In v1 cover letter [1], I illustrated the potential to reduce unnecessary
CPU resources with an experiment with VMs, reducing more than 70% of CPU
usage. The main delta of v2 [2] was that, instead of a weak function that
archs can overwrite, we provided a flexible priority-based mechanism
(following suggestions by Sean Christopherson), panic_set_handling().

Compared to v2 [2], the main changes in this third version are that (1) we
don't set a default function for panic_halt() and (2) we provide a comment
for the x86 implementation describing the check for console.

[1] https://lore.kernel.org/all/20250326151204.67898-1-carlos.bilbao@kernel.org/
[2] https://lore.kernel.org/all/20250428215952.1332985-1-carlos.bilbao@kernel.org/

Carlos:
  panic: Allow for dynamic custom behavior after panic
  x86/panic: Add x86_panic_handler as default post-panic behavior

---
 arch/x86/kernel/setup.c | 17 +++++++++++++++++
 include/linux/panic.h   |  2 ++
 kernel/panic.c          | 22 ++++++++++++++++++++++
 3 files changed, 41 insertions(+)