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Diffstat (limited to 'Documentation/RCU/stallwarn.rst')
| -rw-r--r-- | Documentation/RCU/stallwarn.rst | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst index ca7b7cd806a1..d1ccd6039a8c 100644 --- a/Documentation/RCU/stallwarn.rst +++ b/Documentation/RCU/stallwarn.rst @@ -96,6 +96,13 @@ warnings: the ``rcu_.*timer wakeup didn't happen for`` console-log message, which will include additional debugging information. +- A timer issue causes time to appear to jump forward, so that RCU + believes that the RCU CPU stall-warning timeout has been exceeded + when in fact much less time has passed. This could be due to + timer hardware bugs, timer driver bugs, or even corruption of + the "jiffies" global variable. These sorts of timer hardware + and driver bugs are not uncommon when testing new hardware. + - A low-level kernel issue that either fails to invoke one of the variants of rcu_eqs_enter(true), rcu_eqs_exit(true), ct_idle_enter(), ct_idle_exit(), ct_irq_enter(), or ct_irq_exit() on the one @@ -249,7 +256,7 @@ ticks this GP)" indicates that this CPU has not taken any scheduling-clock interrupts during the current stalled grace period. The "idle=" portion of the message prints the dyntick-idle state. -The hex number before the first "/" is the low-order 12 bits of the +The hex number before the first "/" is the low-order 16 bits of the dynticks counter, which will have an even-numbered value if the CPU is in dyntick-idle mode and an odd-numbered value otherwise. The hex number between the two "/"s is the value of the nesting, which will be |