ouch_timestamp" =
180s-100s > 60s --> printk "soft lockup error messages" ...  }

note: ***(A) reset "touch_timestamp" to
"get_timestamp(this_cpu)"

Why is "touch_timestamp" 100 sec, instead of 180 sec?

When CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is set, the call trace of
get_timestamp() is:

get_timestamp(this_cpu)
 -->cpu_clock(this_cpu)
 -->sched_clock_cpu(this_cpu)
 -->__update_sched_clock(sched_clock_data, now)

The __update_sched_clock() function uses the GTOD tick value to
create a window to normalize the "now" values.  So if "now"
value is too big for sched_clock_data, it will be ignored.

The fix is to invoke sched_clock_tick() to update "cpu sched
clock" in order to recover from this state.  This is done by
introducing the function touch_softlockup_watchdog_sync(). This
allows kgdb to request that the sched clock is updated when the
watchdog thread runs the first time after a resume from kgdb.

[yong.zhang0@gmail.com: Use per cpu instead of an array]
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Dongdong Deng <Dongdong.Deng@windriver.com>
Cc: kgdb-bugreport@lists.sourceforge.net
Cc: peterz@infradead.org
LKML-Reference: <1264631124-4837-2-git-send-email-jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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