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| author | Paul E. McKenney <paulmck@kernel.org> | 2021-07-22 21:41:48 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-09-13 16:32:46 -0700 |
| commit | 13bc8fa8057a064007d4e69c12799450123ef731 (patch) | |
| tree | b98ea9b3e2f7e1de43c03189efc32a7c12058d79 /Documentation/RCU | |
| parent | 9424b867a759febc2b67b6777bfa27f0f830d437 (diff) | |
| download | lwn-13bc8fa8057a064007d4e69c12799450123ef731.tar.gz lwn-13bc8fa8057a064007d4e69c12799450123ef731.zip | |
doc: Add another stall-warning root cause in stallwarn.rst
This commit adds a bullet item noting that both deficiencies and surpluses
of calls to rcu_*_enter() and rcu_*_exit() can result in RCU CPU stall
warnings.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'Documentation/RCU')
| -rw-r--r-- | Documentation/RCU/stallwarn.rst | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst index 5036df24ae61..28f8ad16db25 100644 --- a/Documentation/RCU/stallwarn.rst +++ b/Documentation/RCU/stallwarn.rst @@ -96,6 +96,16 @@ warnings: the ``rcu_.*timer wakeup didn't happen for`` console-log message, which will include additional debugging information. +- A low-level kernel issue that either fails to invoke one of the + variants of rcu_user_enter(), rcu_user_exit(), rcu_idle_enter(), + rcu_idle_exit(), rcu_irq_enter(), or rcu_irq_exit() on the one + hand, or that invokes one of them too many times on the other. + Historically, the most frequent issue has been an omission + of either irq_enter() or irq_exit(), which in turn invoke + rcu_irq_enter() or rcu_irq_exit(), respectively. Building your + kernel with CONFIG_RCU_EQS_DEBUG=y can help track down these types + of issues, which sometimes arise in architecture-specific code. + - A bug in the RCU implementation. - A hardware failure. This is quite unlikely, but has occurred |