Mayank Rungta 077ba03600 watchdog/hardlockup: improve buddy system detection timeliness ... Currently, the buddy system only performs checks every 3rd sample. With a 4-second interval. If a check window is missed, the next check occurs 12 seconds later, potentially delaying hard lockup detection for up to 24 seconds. Modify the buddy system to perform checks at every interval (4s). Introduce a missed-interrupt threshold to maintain the existing grace period while reducing the detection window to 8-12 seconds. Best and worst case detection scenarios: Before (12s check window): - Best case: Lockup occurs after first check but just before heartbeat interval. Detected in ~8s (8s till next check). - Worst case: Lockup occurs just after a check. Detected in ~24s (missed check + 12s till next check + 12s logic). After (4s check window with threshold of 3): - Best case: Lockup occurs just before a check. Detected in ~8s (0s till 1st check + 4s till 2nd + 4s till 3rd). - Worst case: Lockup occurs just after a check. Detected in ~12s (4s till 1st check + 4s till 2nd + 4s till 3rd). Link: https://lkml.kernel.org/r/20260312-hardlockup-watchdog-fixes-v2-4-45bd8a0cc7ed@google.com Signed-off-by: Mayank Rungta <mrungta@google.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Ian Rogers <irogers@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Li Huafei <lihuafei1@huawei.com> Cc: Max Kellermann <max.kellermann@ionos.com> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Stephane Erainan <eranian@google.com> Cc: Wang Jinchao <wangjinchao600@gmail.com> Cc: Yunhui Cui <cuiyunhui@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>		2026-03-27 21:19:47 -07:00
..
bpf	bpf: Fix sync_linked_regs regarding BPF_ADD_CONST32 zext propagation	2026-03-21 13:19:40 -07:00
cgroup	cgroup: Don't expose dead tasks in cgroup	2026-03-06 12:43:25 -10:00
configs	Remove WARN_ALL_UNSEEDED_RANDOM kernel config option	2026-02-23 11:18:48 -08:00
debug	treewide: Replace kmalloc with kmalloc_obj for non-scalar types	2026-02-21 01:02:28 -08:00
dma	dma-mapping: avoid random addr value print out on error path	2026-02-23 08:26:54 +01:00
entry	Merge branch 'core/entry' into sched/core	2026-01-30 15:40:05 +01:00
events	perf: Make sure to use pmu_ctx->pmu for groups	2026-03-12 11:29:16 +01:00
futex	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
gcov	Convert more 'alloc_obj' cases to default GFP_KERNEL arguments	2026-02-21 20:03:00 -08:00
irq	Convert 'alloc_flex' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
kcsan	kcsan: test: Adjust "expect" allocation type for kmalloc_obj	2026-02-26 09:54:08 -08:00
livepatch	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
liveupdate	liveupdate: luo_file: remember retrieve() status	2026-02-24 11:13:26 -08:00
locking	Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses	2026-02-22 08:26:33 -08:00
module	module: Fix kernel panic when a symbol st_shndx is out of bounds	2026-02-23 19:37:28 +00:00
power	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
printk	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
rcu	Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses	2026-02-22 08:26:33 -08:00
sched	sched: idle: Consolidate the handling of two special cases	2026-03-16 20:29:47 +01:00
time	time/jiffies: Mark jiffies_64_to_clock_t() notrace	2026-03-11 10:33:12 +01:00
trace	ftrace: Use hash argument for tmp_ops in update_ftrace_direct_mod	2026-03-21 16:51:04 -04:00
unwind	Convert more 'alloc_obj' cases to default GFP_KERNEL arguments	2026-02-21 20:03:00 -08:00
.gitignore	…
Kconfig.freezer	…
Kconfig.hz	…
Kconfig.kexec	liveupdate: kho: move to kernel/liveupdate	2025-11-27 14:24:33 -08:00
Kconfig.locks	…
Kconfig.preempt	sched: Further restrict the preemption modes	2026-01-08 12:43:57 +01:00
Makefile	kcov: Enable context analysis	2026-01-05 16:43:34 +01:00
acct.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
async.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
audit.c	Convert 'alloc_flex' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
audit.h	…
audit_fsnotify.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
audit_tree.c	Convert 'alloc_flex' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
audit_watch.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
auditfilter.c	Convert 'alloc_flex' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
auditsc.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
backtracetest.c	…
bounds.c	x86/asm: Remove ANNOTATE_DATA_SPECIAL usage	2025-12-03 16:53:19 +01:00
capability.c	…
cfi.c	…
compat.c	…
configs.c	…
context_tracking.c	context_tracking: Remove rcu_task_trace_heavyweight_{enter,exit}()	2026-01-01 16:39:46 +08:00
cpu.c	SPDX updates for 7.0-rc1	2026-02-17 09:46:03 -08:00
cpu_pm.c	…
crash_core.c	kernel/crash: remove inclusion of crypto/sha1.h	2026-03-27 21:19:46 -07:00
crash_core_test.c	…
crash_dump_dm_crypt.c	crash_dump: use sysfs_emit in sysfs show functions	2026-03-27 21:19:38 -07:00
crash_reserve.c	kernel/crash: remove inclusion of crypto/sha1.h	2026-03-27 21:19:46 -07:00
cred.c	cred: remove unused set_security_override_from_ctx()	2026-01-06 20:52:57 -05:00
delayacct.c	delayacct: fix uapi timespec64 definition	2026-02-08 00:13:32 -08:00
dma.c	…
elfcorehdr.c	…
exec_domain.c	…
exit.c	exit: kill unnecessary thread_group_leader() checks in exit_notify() and do_notify_parent()	2026-03-27 21:19:34 -07:00
exit.h	…
extable.c	…
fail_function.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
fork.c	pid: document the PIDNS_ADDING checks in alloc_pid() and copy_process()	2026-03-27 21:19:36 -07:00
freezer.c	…
gen_kheaders.sh	…
groups.c	treewide: Replace kmalloc with kmalloc_obj for non-scalar types	2026-02-21 01:02:28 -08:00
hung_task.c	hung_task: explicitly report I/O wait state in log output	2026-03-27 21:19:40 -07:00
iomem.c	…
irq_work.c	…
jump_label.c	…
kallsyms.c	mm.git review status for linus..mm-nonmm-stable	2026-02-12 12:13:01 -08:00
kallsyms_internal.h	kallsyms: Get rid of kallsyms relative base	2026-01-22 15:58:22 -07:00
kallsyms_selftest.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
kallsyms_selftest.h	…
kcmp.c	…
kcov.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
kexec.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
kexec_core.c	kernel/kexec: remove inclusion of crypto/hash.h	2026-03-27 21:19:46 -07:00
kexec_elf.c	…
kexec_file.c	kexec: derive purgatory entry from symbol	2026-01-31 16:16:07 -08:00
kexec_internal.h	…
kheaders.c	…
kprobes.c	kprobes: Remove unneeded warnings from __arm_kprobe_ftrace()	2026-03-13 23:15:26 +09:00
kstack_erase.c	…
ksyms_common.c	…
ksysfs.c	kexec: move sysfs entries to /sys/kernel/kexec	2025-11-27 14:24:42 -08:00
kthread.c	kthread: consolidate kthread exit paths to prevent use-after-free	2026-02-26 10:45:49 +01:00
latencytop.c	…
module_signature.c	…
notifier.c	…
nscommon.c	nsfs: tighten permission checks for ns iteration ioctls	2026-02-27 22:00:08 +01:00
nsproxy.c	…
nstree.c	nstree: tighten permission checks for listing	2026-02-27 22:00:11 +01:00
padata.c	Convert more 'alloc_obj' cases to default GFP_KERNEL arguments	2026-02-21 20:03:00 -08:00
panic.c	kernel/panic: mark init_taint_buf as __initdata and panic instead of warning in alloc_taint_buf()	2026-03-27 21:19:33 -07:00
params.c	Convert more 'alloc_obj' cases to default GFP_KERNEL arguments	2026-02-21 20:03:00 -08:00
pid.c	pid: document the PIDNS_ADDING checks in alloc_pid() and copy_process()	2026-03-27 21:19:36 -07:00
pid_namespace.c	…
pid_sysctl.h	…
profile.c	…
ptrace.c	…
range.c	…
reboot.c	treewide: Replace kmalloc with kmalloc_obj for non-scalar types	2026-02-21 01:02:28 -08:00
regset.c	…
relay.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
resource.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
resource_kunit.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
rseq.c	rseq: slice ext: Ensure rseq feature size differs from original rseq size	2026-02-23 11:19:19 +01:00
scftorture.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
scs.c	…
seccomp.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
signal.c	complete_signal: kill always-true "core_state || !SIGNAL_GROUP_EXIT" check	2026-03-27 21:19:35 -07:00
smp.c	…
smpboot.c	…
smpboot.h	…
softirq.c	…
stacktrace.c	…
static_call.c	…
static_call_inline.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
stop_machine.c	…
sys.c	RISC-V updates for v7.0	2026-02-12 19:17:44 -08:00
sys_ni.c	rseq: Implement sys_rseq_slice_yield()	2026-01-22 11:11:17 +01:00
sysctl-test.c	…
sysctl.c	sysctl: replace SYSCTL_INT_CONV_CUSTOM macro with functions	2026-01-06 11:27:10 +01:00
task_work.c	…
taskstats.c	…
torture.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
tracepoint.c	Convert 'alloc_flex' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
tsacct.c	tsacct: skip all kernel threads	2026-01-26 19:07:13 -08:00
ucount.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
uid16.c	…
uid16.h	…
umh.c	treewide: Replace kmalloc with kmalloc_obj for non-scalar types	2026-02-21 01:02:28 -08:00
up.c	…
user-return-notifier.c	…
user.c	…
user_namespace.c	Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses	2026-02-22 08:26:33 -08:00
utsname.c	…
utsname_sysctl.c	…
vhost_task.c	Convert 'alloc_obj' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
vmcore_info.c	kernel/crash: remove inclusion of crypto/sha1.h	2026-03-27 21:19:46 -07:00
watch_queue.c	Convert 'alloc_flex' family to use the new default GFP_KERNEL argument	2026-02-21 17:09:51 -08:00
watchdog.c	watchdog/hardlockup: improve buddy system detection timeliness	2026-03-27 21:19:47 -07:00
watchdog_buddy.c	watchdog/hardlockup: improve buddy system detection timeliness	2026-03-27 21:19:47 -07:00
watchdog_perf.c	watchdog/hardlockup: simplify perf event probe and remove per-cpu dependency	2026-02-08 00:13:35 -08:00
workqueue.c	workqueue: Rename show_cpu_pool{s,}_hog{s,}() to reflect broadened scope	2026-03-06 06:38:16 -10:00
workqueue_internal.h	workqueue: Show in-flight work item duration in stall diagnostics	2026-03-05 07:27:48 -10:00