[linux-next:master 9966/13055] kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask'

[linux-next:master 9966/13055] kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   47b7b5e32bb7264b51b89186043e1ada4090b558
commit: a9af76a78760717361cccc884dc649e30db61c8b [9966/13055] watchdog: add sys_info sysctls to dump sys info on system lockup
config: powerpc64-randconfig-002-20251203 (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 734a912d0f025559fcf76bde9aaaeb0383c1625a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask' [-Wunused-variable]
      74 | static unsigned long hardlockup_si_mask;
         |                      ^~~~~~~~~~~~~~~~~~
   1 warning generated.


vim +/hardlockup_si_mask +74 kernel/watchdog.c

    62	
    63	/*
    64	 * Should we panic when a soft-lockup or hard-lockup occurs:
    65	 */
    66	unsigned int __read_mostly hardlockup_panic =
    67				IS_ENABLED(CONFIG_BOOTPARAM_HARDLOCKUP_PANIC);
    68	
    69	/*
    70	 * bitmasks to control what kinds of system info to be printed when
    71	 * hard lockup is detected, it could be task, memory, lock etc.
    72	 * Refer include/linux/sys_info.h for detailed bit definition.
    73	 */
  > 74	static unsigned long hardlockup_si_mask;
    75	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [linux-next:master 9966/13055] kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask'

[Feng Tang]

Hi,

Thanks for the reporting! 

On Wed, Dec 03, 2025 at 09:05:30AM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   47b7b5e32bb7264b51b89186043e1ada4090b558
> commit: a9af76a78760717361cccc884dc649e30db61c8b [9966/13055] watchdog: add sys_info sysctls to dump sys info on system lockup
> config: powerpc64-randconfig-002-20251203 (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/config)
> compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 734a912d0f025559fcf76bde9aaaeb0383c1625a)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask' [-Wunused-variable]
>       74 | static unsigned long hardlockup_si_mask;
>          |                      ^~~~~~~~~~~~~~~~~~
>    1 warning generated.

I can't reproduce it right now as I'm on travel and only have ARM server
to use. (The reproducer need a powerpc64 machine, or have a x86 machine
to use your reproducer script).

Could you help to test the below patch? thank!

- Feng

---
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 1f59b950c475..5e5ac82a01f3 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -66,13 +66,6 @@ int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
 unsigned int __read_mostly hardlockup_panic =
 			IS_ENABLED(CONFIG_BOOTPARAM_HARDLOCKUP_PANIC);
 
-/*
- * bitmasks to control what kinds of system info to be printed when
- * hard lockup is detected, it could be task, memory, lock etc.
- * Refer include/linux/sys_info.h for detailed bit definition.
- */
-static unsigned long hardlockup_si_mask;
-
 #ifdef CONFIG_SYSFS
 
 static unsigned int hardlockup_count;
@@ -141,6 +134,13 @@ static DEFINE_PER_CPU(bool, watchdog_hardlockup_warned);
 static DEFINE_PER_CPU(bool, watchdog_hardlockup_touched);
 static unsigned long hard_lockup_nmi_warn;
 
+/*
+ * bitmasks to control what kinds of system info to be printed when
+ * hard lockup is detected, it could be task, memory, lock etc.
+ * Refer include/linux/sys_info.h for detailed bit definition.
+ */
+static unsigned long hardlockup_si_mask;
+
 notrace void arch_touch_nmi_watchdog(void)
 {
 	/*
@@ -1250,6 +1250,7 @@ static const struct ctl_table watchdog_sysctls[] = {
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
 	{
 		.procname	= "hardlockup_sys_info",
 		.data		= &hardlockup_si_mask,
@@ -1257,6 +1258,7 @@ static const struct ctl_table watchdog_sysctls[] = {
 		.mode		= 0644,
 		.proc_handler	= sysctl_sys_info_handler,
 	},
+#endif
 #ifdef CONFIG_SMP
 	{
 		.procname	= "hardlockup_all_cpu_backtrace",

Re: [linux-next:master 9966/13055] kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask'

[Andrew Morton]

On Wed, 3 Dec 2025 09:05:30 +0800 kernel test robot <lkp@intel.com> wrote:

> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   47b7b5e32bb7264b51b89186043e1ada4090b558
> commit: a9af76a78760717361cccc884dc649e30db61c8b [9966/13055] watchdog: add sys_info sysctls to dump sys info on system lockup
> config: powerpc64-randconfig-002-20251203 (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/config)
> compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 734a912d0f025559fcf76bde9aaaeb0383c1625a)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask' [-Wunused-variable]
>       74 | static unsigned long hardlockup_si_mask;
>          |                      ^~~~~~~~~~~~~~~~~~
>    1 warning generated.

I'm testing the appended patch but it needs checking please.

The comment for hardlockup_si_mask says

 * bitmask to control what kinds of system info to be printed when
 * hard lockup is detected, it could be task, memory, lock etc.
 * Refer include/linux/sys_info.h for detailed bit definition.

but the variable depends on "COUNTS_HRTIMER".  The comment doesn't
mention hrtimers and I don't see why it should.  Not sure what's going
on here.



From: Andrew Morton <akpm@linux-foundation.org>
Subject: kernel/watchdog.c: fix unused var warning
Date: Wed Dec  3 02:34:40 PM PST 2025

>> kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask' [-Wunused-variable]
      74 | static unsigned long hardlockup_si_mask;
         |                      ^~~~~~~~~~~~~~~~~~
   1 warning generated.

Fixes: a9af76a78760 ("watchdog: add sys_info sysctls to dump sys info on system lockup")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
Link: https://lkml.kernel.org/r/202512030920.NFKtekA7-lkp@intel.com
Cc: Feng Tang <feng.tang@linux.alibaba.com>
Cc: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/watchdog.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

--- a/kernel/watchdog.c~kernel-watchdogc-fix-unused-var-warning
+++ a/kernel/watchdog.c
@@ -66,13 +66,6 @@ int __read_mostly sysctl_hardlockup_all_
 unsigned int __read_mostly hardlockup_panic =
 			IS_ENABLED(CONFIG_BOOTPARAM_HARDLOCKUP_PANIC);
 
-/*
- * bitmasks to control what kinds of system info to be printed when
- * hard lockup is detected, it could be task, memory, lock etc.
- * Refer include/linux/sys_info.h for detailed bit definition.
- */
-static unsigned long hardlockup_si_mask;
-
 #ifdef CONFIG_SYSFS
 
 static unsigned int hardlockup_count;
@@ -135,6 +128,13 @@ __setup("nmi_watchdog=", hardlockup_pani
 
 #if defined(CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER)
 
+/*
+ * bitmask to control what kinds of system info to be printed when
+ * hard lockup is detected, it could be task, memory, lock etc.
+ * Refer include/linux/sys_info.h for detailed bit definition.
+ */
+static unsigned long hardlockup_si_mask;
+
 static DEFINE_PER_CPU(atomic_t, hrtimer_interrupts);
 static DEFINE_PER_CPU(int, hrtimer_interrupts_saved);
 static DEFINE_PER_CPU(bool, watchdog_hardlockup_warned);
@@ -1250,6 +1250,7 @@ static const struct ctl_table watchdog_s
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
+#if defined(CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER)
 	{
 		.procname	= "hardlockup_sys_info",
 		.data		= &hardlockup_si_mask,
@@ -1257,6 +1258,7 @@ static const struct ctl_table watchdog_s
 		.mode		= 0644,
 		.proc_handler	= sysctl_sys_info_handler,
 	},
+#endif
 #ifdef CONFIG_SMP
 	{
 		.procname	= "hardlockup_all_cpu_backtrace",
_

Re: [linux-next:master 9966/13055] kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask'

[Petr Mladek]

On Wed 2025-12-03 14:44:53, Andrew Morton wrote:
> On Wed, 3 Dec 2025 09:05:30 +0800 kernel test robot <lkp@intel.com> wrote:
> 
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > head:   47b7b5e32bb7264b51b89186043e1ada4090b558
> > commit: a9af76a78760717361cccc884dc649e30db61c8b [9966/13055] watchdog: add sys_info sysctls to dump sys info on system lockup
> > config: powerpc64-randconfig-002-20251203 (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/config)
> > compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 734a912d0f025559fcf76bde9aaaeb0383c1625a)
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
> > 
> > All warnings (new ones prefixed by >>):
> > 
> > >> kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask' [-Wunused-variable]
> >       74 | static unsigned long hardlockup_si_mask;
> >          |                      ^~~~~~~~~~~~~~~~~~
> >    1 warning generated.
> 
> I'm testing the appended patch but it needs checking please.
> 
> The comment for hardlockup_si_mask says
> 
>  * bitmask to control what kinds of system info to be printed when
>  * hard lockup is detected, it could be task, memory, lock etc.
>  * Refer include/linux/sys_info.h for detailed bit definition.
> 
> but the variable depends on "COUNTS_HRTIMER".  The comment doesn't
> mention hrtimers and I don't see why it should.  Not sure what's going
> on here.

Good point! It took me some time to understand it.

So, powerpc implements its own watchog, see arch/powerpc/kernel/watchdog.c.
The watchdog is supported only by some powerpc platforms, see the
   following line in arch/powerpc/Kconfig:

	select HAVE_HARDLOCKUP_DETECTOR_ARCH	if PPC_BOOK3S_64 && SMP

As a result, the test system could have the following in the config,
see https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/config

	CONFIG_HARDLOCKUP_DETECTOR=y
	# CONFIG_HARDLOCKUP_DETECTOR_PERF is not set
	# CONFIG_HARDLOCKUP_DETECTOR_BUDDY is not set
	CONFIG_HARDLOCKUP_DETECTOR_ARCH=y

And "COUNTS_HRTIMER" is not defined.


> From: Andrew Morton <akpm@linux-foundation.org>
> Subject: kernel/watchdog.c: fix unused var warning
> Date: Wed Dec  3 02:34:40 PM PST 2025
> 
> >> kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask' [-Wunused-variable]
>       74 | static unsigned long hardlockup_si_mask;
>          |                      ^~~~~~~~~~~~~~~~~~
>    1 warning generated.
> 
> Fixes: a9af76a78760 ("watchdog: add sys_info sysctls to dump sys info on system lockup")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
> Link: https://lkml.kernel.org/r/202512030920.NFKtekA7-lkp@intel.com
> Cc: Feng Tang <feng.tang@linux.alibaba.com>
> Cc: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  kernel/watchdog.c |   16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> --- a/kernel/watchdog.c~kernel-watchdogc-fix-unused-var-warning
> +++ a/kernel/watchdog.c
> @@ -66,13 +66,6 @@ int __read_mostly sysctl_hardlockup_all_
>  unsigned int __read_mostly hardlockup_panic =
>  			IS_ENABLED(CONFIG_BOOTPARAM_HARDLOCKUP_PANIC);
>  
> -/*
> - * bitmasks to control what kinds of system info to be printed when
> - * hard lockup is detected, it could be task, memory, lock etc.
> - * Refer include/linux/sys_info.h for detailed bit definition.
> - */
> -static unsigned long hardlockup_si_mask;
> -
>  #ifdef CONFIG_SYSFS
>  
>  static unsigned int hardlockup_count;
> @@ -135,6 +128,13 @@ __setup("nmi_watchdog=", hardlockup_pani
>  
>  #if defined(CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER)
>  
> +/*
> + * bitmask to control what kinds of system info to be printed when
> + * hard lockup is detected, it could be task, memory, lock etc.
> + * Refer include/linux/sys_info.h for detailed bit definition.
> + */
> +static unsigned long hardlockup_si_mask;
> +
>  static DEFINE_PER_CPU(atomic_t, hrtimer_interrupts);
>  static DEFINE_PER_CPU(int, hrtimer_interrupts_saved);
>  static DEFINE_PER_CPU(bool, watchdog_hardlockup_warned);
> @@ -1250,6 +1250,7 @@ static const struct ctl_table watchdog_s
>  		.extra1		= SYSCTL_ZERO,
>  		.extra2		= SYSCTL_ONE,
>  	},
> +#if defined(CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER)
>  	{
>  		.procname	= "hardlockup_sys_info",
>  		.data		= &hardlockup_si_mask,
> @@ -1257,6 +1258,7 @@ static const struct ctl_table watchdog_s
>  		.mode		= 0644,
>  		.proc_handler	= sysctl_sys_info_handler,
>  	},
> +#endif
>  #ifdef CONFIG_SMP
>  	{
>  		.procname	= "hardlockup_all_cpu_backtrace",
> _

This patch makes some sense because the arch-specific watchdog does
not support the sys_info interface. And it is better than nothing.
definitely.

A better solution would be export the variable and handle it
in arch/powerpc/kernel/watchdog.c.

It seems that powerpc is the only architecture which could define
HAVE_HARDLOCKUP_DETECTOR_ARCH.

Feng, would you have time to look at it?

Best Regards,
Petr

Re: [linux-next:master 9966/13055] kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask'

[Feng Tang]

On Thu, Dec 04, 2025 at 02:38:42PM +0100, Petr Mladek wrote:
> On Wed 2025-12-03 14:44:53, Andrew Morton wrote:
> > On Wed, 3 Dec 2025 09:05:30 +0800 kernel test robot <lkp@intel.com> wrote:
> > 
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > > head:   47b7b5e32bb7264b51b89186043e1ada4090b558
> > > commit: a9af76a78760717361cccc884dc649e30db61c8b [9966/13055] watchdog: add sys_info sysctls to dump sys info on system lockup
> > > config: powerpc64-randconfig-002-20251203 (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/config)
> > > compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 734a912d0f025559fcf76bde9aaaeb0383c1625a)
> > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/reproduce)
> > > 
> > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > the same patch/commit), kindly add following tags
> > > | Reported-by: kernel test robot <lkp@intel.com>
> > > | Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
> > > 
> > > All warnings (new ones prefixed by >>):
> > > 
> > > >> kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask' [-Wunused-variable]
> > >       74 | static unsigned long hardlockup_si_mask;
> > >          |                      ^~~~~~~~~~~~~~~~~~
> > >    1 warning generated.
> > 
> > I'm testing the appended patch but it needs checking please.
> > 
> > The comment for hardlockup_si_mask says
> > 
> >  * bitmask to control what kinds of system info to be printed when
> >  * hard lockup is detected, it could be task, memory, lock etc.
> >  * Refer include/linux/sys_info.h for detailed bit definition.
> > 
> > but the variable depends on "COUNTS_HRTIMER".  The comment doesn't
> > mention hrtimers and I don't see why it should.  Not sure what's going
> > on here.
> 
> Good point! It took me some time to understand it.
> 
> So, powerpc implements its own watchog, see arch/powerpc/kernel/watchdog.c.
> The watchdog is supported only by some powerpc platforms, see the
>    following line in arch/powerpc/Kconfig:
> 
> 	select HAVE_HARDLOCKUP_DETECTOR_ARCH	if PPC_BOOK3S_64 && SMP
> 
> As a result, the test system could have the following in the config,
> see https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/config
> 
> 	CONFIG_HARDLOCKUP_DETECTOR=y
> 	# CONFIG_HARDLOCKUP_DETECTOR_PERF is not set
> 	# CONFIG_HARDLOCKUP_DETECTOR_BUDDY is not set
> 	CONFIG_HARDLOCKUP_DETECTOR_ARCH=y
> 
> And "COUNTS_HRTIMER" is not defined.

Thanks for the check!

Was working on a reply at the same time :)

> > @@ -1250,6 +1250,7 @@ static const struct ctl_table watchdog_s
> >  		.extra1		= SYSCTL_ZERO,
> >  		.extra2		= SYSCTL_ONE,
> >  	},
> > +#if defined(CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER)
> >  	{
> >  		.procname	= "hardlockup_sys_info",
> >  		.data		= &hardlockup_si_mask,
> > @@ -1257,6 +1258,7 @@ static const struct ctl_table watchdog_s
> >  		.mode		= 0644,
> >  		.proc_handler	= sysctl_sys_info_handler,
> >  	},
> > +#endif
> >  #ifdef CONFIG_SMP
> >  	{
> >  		.procname	= "hardlockup_all_cpu_backtrace",
> > _
> 
> This patch makes some sense because the arch-specific watchdog does
> not support the sys_info interface. And it is better than nothing.
> definitely.
> 
> A better solution would be export the variable and handle it
> in arch/powerpc/kernel/watchdog.c.

Yep!

> It seems that powerpc is the only architecture which could define
> HAVE_HARDLOCKUP_DETECTOR_ARCH.
> 
> Feng, would you have time to look at it?

Sure.

Thanks,
Feng

Re: [linux-next:master 9966/13055] kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask'

[Feng Tang]

On Wed, Dec 03, 2025 at 02:44:53PM -0800, Andrew Morton wrote:
> On Wed, 3 Dec 2025 09:05:30 +0800 kernel test robot <lkp@intel.com> wrote:
> 
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > head:   47b7b5e32bb7264b51b89186043e1ada4090b558
> > commit: a9af76a78760717361cccc884dc649e30db61c8b [9966/13055] watchdog: add sys_info sysctls to dump sys info on system lockup
> > config: powerpc64-randconfig-002-20251203 (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/config)
> > compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 734a912d0f025559fcf76bde9aaaeb0383c1625a)
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251203/202512030920.NFKtekA7-lkp@intel.com/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
> > 
> > All warnings (new ones prefixed by >>):
> > 
> > >> kernel/watchdog.c:74:22: warning: unused variable 'hardlockup_si_mask' [-Wunused-variable]
> >       74 | static unsigned long hardlockup_si_mask;
> >          |                      ^~~~~~~~~~~~~~~~~~
> >    1 warning generated.
> 
> I'm testing the appended patch but it needs checking please.
> 
> The comment for hardlockup_si_mask says
> 
>  * bitmask to control what kinds of system info to be printed when
>  * hard lockup is detected, it could be task, memory, lock etc.
>  * Refer include/linux/sys_info.h for detailed bit definition.
> 
> but the variable depends on "COUNTS_HRTIMER".  The comment doesn't
> mention hrtimers and I don't see why it should.  Not sure what's going
> on here.

Yes, it is a little weird. Logically the 'hardlockup_si_mask' should be
under the CONFIG_HARDLOCKUP_DETECTOR, which is what my original patch did.

I did a quick check, and there are 3 types of hardlockup detector:

	 HARDLOCKUP_DETECTOR_PERF
	 HARDLOCKUP_DETECTOR_BUDDY
	 HARDLOCKUP_DETECTOR_ARCH

IIUC, most archs will use the first 2 types, which will both select
HARDLOCKUP_DETECTOR_COUNTS_HRTIMER (lib/Kconfig.debug), which is kind of
a _proxy_ to select SOFTLOCKUP_DETECTOR which needs hrtimer for its
implementations.

And only very few arch may chose the 3rd architecture specific implementation,
which was in 0day bot's kernel config.

In arch/powerpc/Kconfig
	select HAVE_HARDLOCKUP_DETECTOR_ARCH	if PPC_BOOK3S_64 && SMP
	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI

In short, for most cases the hrtimer is used for soft/hard lockup detector.

Thanks,
Feng