linux/kernel
Prarit Bhargava 8dcde9def5 kernel/watchdog.c: do not hardcode CPU 0 as the initial thread
When CONFIG_BOOTPARAM_HOTPLUG_CPU0 is enabled, the socket containing the
boot cpu can be replaced.  During the hot add event, the message

NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.

is output implying that the NMI watchdog was disabled at some point.  This
is not the case and the message has caused confusion for users of systems
that support the removal of the boot cpu socket.

The watchdog code is coded to assume that cpu 0 is always the first cpu to
initialize the watchdog, and the last to stop its watchdog thread.  That
is not the case for initializing if cpu 0 has been removed and added.  The
removal case has never been correct because the smpboot code will remove
the watchdog threads starting with the lowest cpu number.

This patch adds watchdog_cpus to track the number of cpus with active NMI
watchdog threads so that the first and last thread can be used to set and
clear the value of firstcpu_err.  firstcpu_err is set when the first
watchdog thread is enabled, and cleared when the last watchdog thread is
disabled.

Link: http://lkml.kernel.org/r/1480425321-32296-1-git-send-email-prarit@redhat.com
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Joshua Hunt <johunt@akamai.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Babu Moger <babu.moger@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 16:41:27 -08:00
..
bpf bpf: make jited programs visible in traces 2017-02-17 13:40:05 -05:00
configs arch: Rename CONFIG_DEBUG_RODATA and CONFIG_DEBUG_MODULE_RONX 2017-02-07 12:32:52 -08:00
debug kdb: call vkdb_printf() from vprintk_default() only when wanted 2016-12-14 16:04:08 -08:00
events Linux 4.10-rc8 2017-02-14 07:29:14 +01:00
gcov gcov: add support for gcc version >= 6 2016-07-15 14:54:27 +09:00
irq IOMMU Updates for Linux v4.11 2017-02-20 16:42:43 -08:00
livepatch livepatch/module: make TAINT_LIVEPATCH module-specific 2016-08-26 14:42:08 +02:00
locking Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-02-20 13:23:30 -08:00
power This renames the (now inaccurate) CONFIG_DEBUG_RODATA and related config 2017-02-21 17:56:45 -08:00
printk printk: use rcuidle console tracepoint 2017-02-18 17:27:00 -08:00
rcu Merge branches 'doc.2017.01.15b', 'dyntick.2017.01.23a', 'fixes.2017.01.23a', 'srcu.2017.01.25a' and 'torture.2017.01.15b' into HEAD 2017-01-25 12:56:05 -08:00
sched sched/core: Fix build paravirt build on arm and arm64 2017-02-21 10:54:02 -08:00
time Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-02-20 12:52:55 -08:00
trace tracing: add __print_flags_u64() 2017-02-22 16:41:26 -08:00
.gitignore
acct.c acct: Convert obsolete cputime type to nsecs 2017-02-01 09:13:51 +01:00
async.c
audit_fsnotify.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
audit_tree.c Merge branch 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit 2017-01-05 23:06:06 -08:00
audit_watch.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
audit.c Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit 2017-02-21 13:25:50 -08:00
audit.h Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit 2017-02-21 13:25:50 -08:00
auditfilter.c audit: add support for session ID user filter 2016-11-29 15:10:12 -05:00
auditsc.c Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit 2017-02-21 13:25:50 -08:00
backtracetest.c
bounds.c
capability.c capability: export has_capability 2017-01-12 07:01:56 -07:00
cgroup_freezer.c
cgroup_pids.c cgroup: Use lld instead of ld when printing pids controller events_limit 2016-06-21 15:03:36 -04:00
cgroup.c bpf: introduce BPF_F_ALLOW_OVERRIDE flag 2017-02-12 21:52:19 -05:00
compat.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
configs.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
context_tracking.c
cpu_pm.c
cpu.c cpu/hotplug: Remove unused but set variable in _cpu_down() 2017-01-18 11:55:09 +01:00
cpuset.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
crash_dump.c
cred.c cred: Reject inodes with invalid ids in set_create_file_as() 2016-06-30 18:05:09 -05:00
delayacct.c delaycct: Convert obsolete cputime type to nsecs 2017-02-01 09:13:52 +01:00
dma.c
elfcore.c
exec_domain.c
exit.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2017-02-21 12:49:56 -08:00
extable.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-02-22 10:15:09 -08:00
fork.c Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-02-20 13:23:30 -08:00
freezer.c freezer, oom: check TIF_MEMDIE on the correct task 2016-07-28 16:07:41 -07:00
futex_compat.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
futex.c futex: Move futex_init() to core_initcall 2017-02-13 16:12:22 +01:00
groups.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
hung_task.c hung_task: decrement sysctl_hung_task_warnings only if it is positive 2016-12-12 18:55:09 -08:00
irq_work.c
jump_label.c jump_labels: API for flushing deferred jump label updates 2017-01-12 14:33:16 +01:00
kallsyms.c bpf: make jited programs visible in traces 2017-02-17 13:40:05 -05:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/mutex: Allow MUTEX_SPIN_ON_OWNER when DEBUG_MUTEXES 2016-10-25 11:31:51 +02:00
Kconfig.preempt
kcov.c kcov: make kcov work properly with KASLR enabled 2016-12-20 09:48:47 -08:00
kexec_core.c kexec: Switch to __pa_symbol 2017-01-11 13:56:49 +00:00
kexec_file.c ima: on soft reboot, save the measurement list 2016-12-20 09:48:44 -08:00
kexec_internal.h kexec_file: Allow arch-specific memory walking for kexec_add_buffer 2016-11-30 23:14:57 +11:00
kexec.c kexec: allow architectures to override boot mapping 2016-08-02 19:35:27 -04:00
kmod.c Introduce STATIC_USERMODEHELPER to mediate call_usermodehelper() 2017-01-19 12:59:45 +01:00
kprobes.c powerpc updates for 4.11 part 1. 2017-02-22 10:30:38 -08:00
ksysfs.c kexec: add a kexec_crash_loaded() function 2016-08-02 19:35:30 -04:00
kthread.c time: Remove CONFIG_TIMER_STATS 2017-02-10 11:15:08 +01:00
latencytop.c
Makefile Merge branch 'akpm' (patches from Andrew) 2016-12-14 17:25:18 -08:00
membarrier.c Fix: Disable sys_membarrier when nohz_full is enabled 2017-01-23 11:32:16 -08:00
memremap.c mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done} 2017-01-10 18:31:54 -08:00
module_signing.c
module-internal.h
module.c This renames the (now inaccurate) CONFIG_DEBUG_RODATA and related config 2017-02-21 17:56:45 -08:00
notifier.c
nsproxy.c
padata.c padata: Remove unused but set variables 2016-10-25 11:08:10 +08:00
panic.c kernel/panic.c: add missing \n 2017-01-24 16:26:14 -08:00
params.c
pid_namespace.c pid: fix lockdep deadlock warning due to ucount_lock 2017-01-10 13:34:56 +13:00
pid.c locking/atomic, kref: Add KREF_INIT() 2017-01-14 11:37:18 +01:00
profile.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ptrace.c ptrace: Don't allow accessing an undumpable mm 2016-11-22 12:57:38 -06:00
range.c
reboot.c
relay.c relay: check array offset before using it 2016-12-14 16:04:08 -08:00
resource.c
seccomp.c seccomp: dump core when using SECCOMP_RET_KILL 2017-01-23 21:42:42 +11:00
signal.c signal: Convert obsolete cputime type to nsecs 2017-02-01 09:13:53 +01:00
smp.c kernel/smp: Tell the user we're bringing up secondary CPUs 2016-10-26 12:02:35 +02:00
smpboot.c kthread/smpboot: do not park in kthread_create_on_cpu() 2016-10-11 15:06:33 -07:00
smpboot.h
softirq.c softirq: Display IRQ_POLL for irq-poll statistics 2016-10-21 15:45:47 -06:00
stacktrace.c stacktrace, lockdep: Fix address, newline ugliness 2017-02-08 08:21:31 +01:00
stop_machine.c locking/core, stop_machine: Yield the CPU during stop machine() 2016-11-16 10:15:09 +01:00
sys_ni.c move aio compat to fs/aio.c 2016-12-22 22:58:37 -05:00
sys.c sched/cputime: Convert task/group cputime to nsecs 2017-02-01 09:13:49 +01:00
sysctl_binary.c sysctl: add KERN_CONT to deprecated_sysctl_warning() 2016-12-14 16:04:07 -08:00
sysctl.c sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds 2017-02-01 11:01:30 +01:00
task_work.c task_work: use READ_ONCE/lockless_dereference, avoid pi_lock if !task_works 2016-08-02 19:35:02 -04:00
taskstats.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-15 10:54:36 -05:00
test_kprobes.c
torture.c torture: Convert torture_shutdown() to hrtimer 2016-08-22 10:01:49 -07:00
tracepoint.c tracing: Have the reg function allow to fail 2016-12-09 09:13:30 -05:00
tsacct.c tsacct: Convert obsolete cputime type to nsecs 2017-02-01 09:13:52 +01:00
ucount.c kernel/ucount.c: mark user_header with kmemleak_ignore() 2017-02-08 15:41:43 -08:00
uid16.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
up.c smp: Add function to execute a function synchronously on a CPU 2016-09-05 13:52:39 +02:00
user_namespace.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
user-return-notifier.c
user.c
utsname_sysctl.c
utsname.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
watchdog_hld.c kernel/watchdog.c: do not hardcode CPU 0 as the initial thread 2017-02-22 16:41:27 -08:00
watchdog.c kernel/watchdog: prevent false hardlockup on overloaded system 2017-01-24 16:26:14 -08:00
workqueue_internal.h
workqueue.c time: Remove CONFIG_TIMER_STATS 2017-02-10 11:15:08 +01:00