kernel/time/clocksource.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
With commit 4ac1dd3245b9("clocksource: Set cs_watchdog_read() checks
based on .uncertainty_margin"), the limit for wd-cs-wd read back delay
is changed from the static WATCHDOG_MAX_SKEW to dynamic ones based on
watchdog and cs' uncertainty_margin, but WATCHDOG_MAX_SKEW is still used
when dumping information.
Fix this by using the actual limit: md(2 * watchdog->uncertainty_margin)
+ cs->unvertainty_margin.
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
---
kernel/time/clocksource.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index e400fe150f9d7..ae0fcd5af41c2 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -290,7 +290,7 @@ static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow,
}
pr_warn("timekeeping watchdog on CPU%d: wd-%s-wd excessive read-back delay of %lldns vs. limit of %ldns, wd-wd read-back delay only %lldns, attempt %d, marking %s unstable\n",
- smp_processor_id(), cs->name, wd_delay, WATCHDOG_MAX_SKEW, wd_seq_delay, nretries, cs->name);
+ smp_processor_id(), cs->name, wd_delay, md + cs->uncertainty_margin, wd_seq_delay, nretries, cs->name);
return WD_READ_UNSTABLE;
skip_test:
--
2.39.5Hi Aaron,
kernel test robot noticed the following build warnings:
[auto build test WARNING on tip/timers/core]
[also build test WARNING on linus/master v6.16 next-20250731]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Aaron-Lu/clocksource-Use-correct-limit-for-wd-cs-wd-read-back-delay-in-printing/20250731-200709
base: tip/timers/core
patch link: https://lore.kernel.org/r/20250731120454.GA309%40bytedance
patch subject: [PATCH] clocksource: Use correct limit for wd-cs-wd read back delay in printing
config: i386-buildonly-randconfig-001-20250801 (https://download.01.org/0day-ci/archive/20250801/202508010911.AmkxEw1p-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250801/202508010911.AmkxEw1p-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/202508010911.AmkxEw1p-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> kernel/time/clocksource.c:293:43: warning: format specifies type 'long' but the argument has type 'int64_t' (aka 'long long') [-Wformat]
292 | pr_warn("timekeeping watchdog on CPU%d: wd-%s-wd excessive read-back delay of %lldns vs. limit of %ldns, wd-wd read-back delay only %lldns, attempt %d, marking %s unstable\n",
| ~~~
| %lld
293 | smp_processor_id(), cs->name, wd_delay, md + cs->uncertainty_margin, wd_seq_delay, nretries, cs->name);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/printk.h:560:37: note: expanded from macro 'pr_warn'
560 | printk(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
| ~~~ ^~~~~~~~~~~
include/linux/printk.h:507:60: note: expanded from macro 'printk'
507 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
| ~~~ ^~~~~~~~~~~
include/linux/printk.h:479:19: note: expanded from macro 'printk_index_wrap'
479 | _p_func(_fmt, ##__VA_ARGS__); \
| ~~~~ ^~~~~~~~~~~
1 warning generated.
vim +293 kernel/time/clocksource.c
252
253 static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow, u64 *wdnow)
254 {
255 int64_t md = 2 * watchdog->uncertainty_margin;
256 unsigned int nretries, max_retries;
257 int64_t wd_delay, wd_seq_delay;
258 u64 wd_end, wd_end2;
259
260 max_retries = clocksource_get_max_watchdog_retry();
261 for (nretries = 0; nretries <= max_retries; nretries++) {
262 local_irq_disable();
263 *wdnow = watchdog->read(watchdog);
264 *csnow = cs->read(cs);
265 wd_end = watchdog->read(watchdog);
266 wd_end2 = watchdog->read(watchdog);
267 local_irq_enable();
268
269 wd_delay = cycles_to_nsec_safe(watchdog, *wdnow, wd_end);
270 if (wd_delay <= md + cs->uncertainty_margin) {
271 if (nretries > 1 && nretries >= max_retries) {
272 pr_warn("timekeeping watchdog on CPU%d: %s retried %d times before success\n",
273 smp_processor_id(), watchdog->name, nretries);
274 }
275 return WD_READ_SUCCESS;
276 }
277
278 /*
279 * Now compute delay in consecutive watchdog read to see if
280 * there is too much external interferences that cause
281 * significant delay in reading both clocksource and watchdog.
282 *
283 * If consecutive WD read-back delay > md, report
284 * system busy, reinit the watchdog and skip the current
285 * watchdog test.
286 */
287 wd_seq_delay = cycles_to_nsec_safe(watchdog, wd_end, wd_end2);
288 if (wd_seq_delay > md)
289 goto skip_test;
290 }
291
292 pr_warn("timekeeping watchdog on CPU%d: wd-%s-wd excessive read-back delay of %lldns vs. limit of %ldns, wd-wd read-back delay only %lldns, attempt %d, marking %s unstable\n",
> 293 smp_processor_id(), cs->name, wd_delay, md + cs->uncertainty_margin, wd_seq_delay, nretries, cs->name);
294 return WD_READ_UNSTABLE;
295
296 skip_test:
297 pr_info("timekeeping watchdog on CPU%d: %s wd-wd read-back delay of %lldns\n",
298 smp_processor_id(), watchdog->name, wd_seq_delay);
299 pr_info("wd-%s-wd read-back delay of %lldns, clock-skew test skipped!\n",
300 cs->name, wd_delay);
301 return WD_READ_SKIP;
302 }
303
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On Fri, Aug 01, 2025 at 09:48:40AM +0800, kernel test robot wrote:
> Hi Aaron,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on tip/timers/core]
> [also build test WARNING on linus/master v6.16 next-20250731]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Aaron-Lu/clocksource-Use-correct-limit-for-wd-cs-wd-read-back-delay-in-printing/20250731-200709
> base: tip/timers/core
> patch link: https://lore.kernel.org/r/20250731120454.GA309%40bytedance
> patch subject: [PATCH] clocksource: Use correct limit for wd-cs-wd read back delay in printing
> config: i386-buildonly-randconfig-001-20250801 (https://download.01.org/0day-ci/archive/20250801/202508010911.AmkxEw1p-lkp@intel.com/config)
> compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250801/202508010911.AmkxEw1p-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/202508010911.AmkxEw1p-lkp@intel.com/
>
> All warnings (new ones prefixed by >>):
>
> >> kernel/time/clocksource.c:293:43: warning: format specifies type 'long' but the argument has type 'int64_t' (aka 'long long') [-Wformat]
> 292 | pr_warn("timekeeping watchdog on CPU%d: wd-%s-wd excessive read-back delay of %lldns vs. limit of %ldns, wd-wd read-back delay only %lldns, attempt %d, marking %s unstable\n",
> | ~~~
> | %lld
Thanks for catching this, will fix it in next version.
> 293 | smp_processor_id(), cs->name, wd_delay, md + cs->uncertainty_margin, wd_seq_delay, nretries, cs->name);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
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