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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 30080ff6f406..d7c8eff63317 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 @@ -112,7 +119,7 @@ warnings: uncommon in large datacenter. In one memorable case some decades back, a CPU failed in a running system, becoming unresponsive, but not causing an immediate crash. This resulted in a series - of RCU CPU stall warnings, eventually leading the realization + of RCU CPU stall warnings, eventually leading to the realization that the CPU had failed. The RCU, RCU-sched, RCU-tasks, and RCU-tasks-trace implementations have |