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watchdog: softlockup: panic when lockup duration exceeds N thresholds

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The softlockup_panic sysctl is currently a binary option: panic
immediately or never panic on soft lockups.

Panicking on any soft lockup, regardless of duration, can be overly
aggressive for brief stalls that may be caused by legitimate operations. 
Conversely, never panicking may allow severe system hangs to persist
undetected.

Extend softlockup_panic to accept an integer threshold, allowing the
kernel to panic only when the normalized lockup duration exceeds N
watchdog threshold periods.  This provides finer-grained control to
distinguish between transient delays and persistent system failures.

The accepted values are:
- 0: Don't panic (unchanged)
- 1: Panic when duration >= 1 * threshold (20s default, original behavior)
- N > 1: Panic when duration >= N * threshold (e.g., 2 = 40s, 3 = 60s.)

The original behavior is preserved for values 0 and 1, maintaining full
backward compatibility while allowing systems to tolerate brief lockups
while still catching severe, persistent hangs.

[lirongqing@baidu.com: v2]
  Link: https://lkml.kernel.org/r/20251218074300.4080-1-lirongqing@baidu.com
Link: https://lkml.kernel.org/r/20251216074521.2796-1-lirongqing@baidu.com
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Li RongQing
2025-12-16 02:45:21 -05:00
committed by Andrew Morton
parent b5bfcc1ffe
commit e700f5d156
13 changed files with 28 additions and 25 deletions
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13
lib/Kconfig.debug
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@@ -1110,13 +1110,14 @@ config SOFTLOCKUP_DETECTOR_INTR_STORM
the CPU stats and the interrupt counts during the "soft lockups".
config BOOTPARAM_SOFTLOCKUP_PANIC
bool "Panic (Reboot) On Soft Lockups"
int "Panic (Reboot) On Soft Lockups"
depends on SOFTLOCKUP_DETECTOR
default 0
help
Say Y here to enable the kernel to panic on "soft lockups",
which are bugs that cause the kernel to loop in kernel
mode for more than 20 seconds (configurable using the watchdog_thresh
sysctl), without giving other tasks a chance to run.
Set to a non-zero value N to enable the kernel to panic on "soft
lockups", which are bugs that cause the kernel to loop in kernel
mode for more than (N * 20 seconds) (configurable using the
watchdog_thresh sysctl), without giving other tasks a chance to run.
The panic can be used in combination with panic_timeout,
to cause the system to reboot automatically after a
@@ -1124,7 +1125,7 @@ config BOOTPARAM_SOFTLOCKUP_PANIC
high-availability systems that have uptime guarantees and
where a lockup must be resolved ASAP.
Say N if unsure.
Say 0 if unsure.
config HAVE_HARDLOCKUP_DETECTOR_BUDDY
bool