rcu: Fix CONFIG_RCU_FAST_NO_HZ stall warning message
The print_cpu_stall_fast_no_hz() function attempts to print -1 when the ->idle_gp_timer is not pending, but unsigned arithmetic causes it to instead print ULONG_MAX, which is 4294967295 on 32-bit systems and 18446744073709551615 on 64-bit systems. Neither of these are the most reader-friendly values, so this commit instead causes "timer not pending" to be printed when ->idle_gp_timer is not pending. Reported-by: Paul Walmsley <paul@pwsan.com> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
parent
22a767269a
commit
86f343b50b
@ -99,7 +99,7 @@ In kernels with CONFIG_RCU_FAST_NO_HZ, even more information is
|
||||
printed:
|
||||
|
||||
INFO: rcu_preempt detected stall on CPU
|
||||
0: (64628 ticks this GP) idle=dd5/3fffffffffffffff/0 drain=0 . timer=-1
|
||||
0: (64628 ticks this GP) idle=dd5/3fffffffffffffff/0 drain=0 . timer not pending
|
||||
(t=65000 jiffies)
|
||||
|
||||
The "(64628 ticks this GP)" indicates that this CPU has taken more
|
||||
@ -116,13 +116,13 @@ number between the two "/"s is the value of the nesting, which will
|
||||
be a small positive number if in the idle loop and a very large positive
|
||||
number (as shown above) otherwise.
|
||||
|
||||
For CONFIG_RCU_FAST_NO_HZ kernels, the "drain=0" indicates that the
|
||||
CPU is not in the process of trying to force itself into dyntick-idle
|
||||
state, the "." indicates that the CPU has not given up forcing RCU
|
||||
into dyntick-idle mode (it would be "H" otherwise), and the "timer=-1"
|
||||
indicates that the CPU has not recented forced RCU into dyntick-idle
|
||||
mode (it would otherwise indicate the number of microseconds remaining
|
||||
in this forced state).
|
||||
For CONFIG_RCU_FAST_NO_HZ kernels, the "drain=0" indicates that the CPU is
|
||||
not in the process of trying to force itself into dyntick-idle state, the
|
||||
"." indicates that the CPU has not given up forcing RCU into dyntick-idle
|
||||
mode (it would be "H" otherwise), and the "timer not pending" indicates
|
||||
that the CPU has not recently forced RCU into dyntick-idle mode (it
|
||||
would otherwise indicate the number of microseconds remaining in this
|
||||
forced state).
|
||||
|
||||
|
||||
Multiple Warnings From One Stall
|
||||
|
@ -2130,11 +2130,15 @@ static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
|
||||
{
|
||||
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
|
||||
struct timer_list *tltp = &rdtp->idle_gp_timer;
|
||||
char c;
|
||||
|
||||
sprintf(cp, "drain=%d %c timer=%lu",
|
||||
rdtp->dyntick_drain,
|
||||
rdtp->dyntick_holdoff == jiffies ? 'H' : '.',
|
||||
timer_pending(tltp) ? tltp->expires - jiffies : -1);
|
||||
c = rdtp->dyntick_holdoff == jiffies ? 'H' : '.';
|
||||
if (timer_pending(tltp))
|
||||
sprintf(cp, "drain=%d %c timer=%lu",
|
||||
rdtp->dyntick_drain, c, tltp->expires - jiffies);
|
||||
else
|
||||
sprintf(cp, "drain=%d %c timer not pending",
|
||||
rdtp->dyntick_drain, c);
|
||||
}
|
||||
|
||||
#else /* #ifdef CONFIG_RCU_FAST_NO_HZ */
|
||||
|
Loading…
Reference in New Issue
Block a user