From: Paul E. McKenney Date: Mon, 3 Oct 2011 00:21:18 +0000 (-0700) Subject: rcu: Document failing tick as cause of RCU CPU stall warning X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2c01531f08f8ba663a20d8472a3032f6df133b6e;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git rcu: Document failing tick as cause of RCU CPU stall warning One of lclaudio's systems was seeing RCU CPU stall warnings from idle. These turned out to be caused by a bug that stopped scheduling-clock tick interrupts from being sent to a given CPU for several hundred seconds. This commit therefore updates the documentation to call this out as a possible cause for RCU CPU stall warnings. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index 4e959208f736..f3e0625f4290 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -101,6 +101,11 @@ o A CPU-bound real-time task in a CONFIG_PREEMPT_RT kernel that CONFIG_TREE_PREEMPT_RCU case, you might see stall-warning messages. +o A hardware or software issue shuts off the scheduler-clock + interrupt on a CPU that is not in dyntick-idle mode. This + problem really has happened, and seems to be most likely to + result in RCU CPU stall warnings for CONFIG_NO_HZ=n kernels. + o A bug in the RCU implementation. o A hardware failure. This is quite unlikely, but has occurred