path: root/Documentation/RCU/stallwarn.txt
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Diffstat (limited to 'Documentation/RCU/stallwarn.txt')
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt
index efb9454875ab..0f7fb4298e7e 100644
--- a/Documentation/RCU/stallwarn.txt
+++ b/Documentation/RCU/stallwarn.txt
@@ -205,6 +205,13 @@ o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the
behavior, you might need to replace some of the cond_resched()
calls with calls to cond_resched_rcu_qs().
+o Booting Linux using a console connection that is too slow to
+ keep up with the boot-time console-message rate. For example,
+ a 115Kbaud serial console can be -way- too slow to keep up
+ with boot-time message rates, and will frequently result in
+ RCU CPU stall warning messages. Especially if you have added
+ debug printk()s.
o Anything that prevents RCU's grace-period kthreads from running.
This can result in the "All QSes seen" console-log message.
This message will include information on when the kthread last