Merge tag 'clocksource.2023.08.15a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull clocksource watchdog updates from Paul McKenney:

 - Handle negative skews in "skew is too large" messages

 - Extend watchdog check exemption to 4-Socket platforms

* tag 'clocksource.2023.08.15a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  x86/tsc: Extend watchdog check exemption to 4-Sockets platform
  clocksource: Handle negative skews in "skew is too large" messages

Author: torvalds

arch/x86/kernel/tsc.c

@@ -1258,7 +1258,7 @@ static void __init check_system_tsc_reliable(void)
 	if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) &&
 	    boot_cpu_has(X86_FEATURE_NONSTOP_TSC) &&
 	    boot_cpu_has(X86_FEATURE_TSC_ADJUST) &&
-	    nr_online_nodes <= 2)
+	    nr_online_nodes <= 4)
 		tsc_disable_clocksource_watchdog();
 }
 

kernel/time/clocksource.c

@@ -473,8 +473,8 @@ static void clocksource_watchdog(struct timer_list *unused)
 		/* Check the deviation from the watchdog clocksource. */
 		md = cs->uncertainty_margin + watchdog->uncertainty_margin;
 		if (abs(cs_nsec - wd_nsec) > md) {
-			u64 cs_wd_msec;
-			u64 wd_msec;
+			s64 cs_wd_msec;
+			s64 wd_msec;
 			u32 wd_rem;
 
 			pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n",
@@ -483,8 +483,8 @@ static void clocksource_watchdog(struct timer_list *unused)
 				watchdog->name, wd_nsec, wdnow, wdlast, watchdog->mask);
 			pr_warn("                      '%s' cs_nsec: %lld cs_now: %llx cs_last: %llx mask: %llx\n",
 				cs->name, cs_nsec, csnow, cslast, cs->mask);
-			cs_wd_msec = div_u64_rem(cs_nsec - wd_nsec, 1000U * 1000U, &wd_rem);
-			wd_msec = div_u64_rem(wd_nsec, 1000U * 1000U, &wd_rem);
+			cs_wd_msec = div_s64_rem(cs_nsec - wd_nsec, 1000 * 1000, &wd_rem);
+			wd_msec = div_s64_rem(wd_nsec, 1000 * 1000, &wd_rem);
 			pr_warn("                      Clocksource '%s' skewed %lld ns (%lld ms) over watchdog '%s' interval of %lld ns (%lld ms)\n",
 				cs->name, cs_nsec - wd_nsec, cs_wd_msec, watchdog->name, wd_nsec, wd_msec);
 			if (curr_clocksource == cs)