user/sven/linux.git/kernel/rcu, branch v5.0.3

rcutorture: Don't do busted forward-progress testing

2018-12-01T20:45:42Z

The "busted" rcutorture type is an intentionally broken implementation of RCU. Doing forward-progress testing on this implementation is not particularly meaningful on the one hand and can result in fatal abuse of the memory allocator on the other. This commit therefore disables forward-progress testing of the "busted" rcutorture type. Reported-by: kernel test robot Signed-off-by: Paul E. McKenney

rcutorture: Use 100ms buckets for forward-progress callback histograms

2018-12-01T20:45:41Z

This commit narrows the scope of each bucket of the forward-progress callback-invocation histograms from one second to 100 milliseconds, which aids debugging of forward-progress problems by making shorter-duration callback-invocation stalls visible. Signed-off-by: Paul E. McKenney

rcutorture: Recover from OOM during forward-progress tests

2018-12-01T20:45:41Z

This commit causes the OOM handler to do rcu_barrier() calls and to free up forward-progress callbacks in order to recover from OOM events. The current test is terminated, but subsequent forward-progress tests can proceed. This allows a long test to result in multiple forward-progress failures, greatly reducing the required testing time. Signed-off-by: Paul E. McKenney

rcutorture: Print forward-progress test age upon failure

2018-12-01T20:45:40Z

This commit prints the age of the forward-progress test in jiffies, in order to allow better interpretation of the callback-invocation histograms. Signed-off-by: Paul E. McKenney

rcutorture: Print time since GP end upon forward-progress failure

2018-12-01T20:45:40Z

If rcutorture's forward-progress tests fail while a grace period is not in progress, it is useful to print the time since the last grace period ended as a way to detect failure to launch a new grace period. This commit therefore makes this change. Signed-off-by: Paul E. McKenney

rcutorture: Print histogram of CB invocation at OOM time

2018-12-01T20:45:39Z

One reason why a forward-progress test might fail would be if something prevented or delayed callback invocation. This commit therefore adds a callback-invocation histogram printout when OOM is reported to rcutorture. Signed-off-by: Paul E. McKenney

rcutorture: Print GP age upon forward-progress failure

2018-12-01T20:45:38Z

Signed-off-by: Paul E. McKenney

rcu: Print per-CPU callback counts for forward-progress failures

2018-12-01T20:45:38Z

This commit prints out the non-zero per-CPU callback counts when a forware-progress error (OOM event) occurs. Signed-off-by: Paul E. McKenney [ paulmck: Fix a pair of uninitialized locals spotted by kbuild test robot. ]

rcu: Account for nocb-CPU callback counts in RCU CPU stall warnings

2018-12-01T20:45:37Z

The RCU CPU stall warnings print an estimate of the total number of RCU callbacks queued in the system, but this estimate leaves out the callbacks queued for nocbs CPUs. This commit therefore introduces rcu_get_n_cbs_cpu(), which gives an accurate callback estimate for both nocbs and normal CPUs, and uses this new function as needed. This commit also introduces a rcu_get_n_cbs_nocb_cpu() helper function that returns the number of callbacks for nocbs CPUs or zero otherwise, and also uses this function in place of direct access to ->nocb_q_count while in the area (fewer characters, you see). Signed-off-by: Paul E. McKenney

rcutorture: Dump grace-period diagnostics upon forward-progress OOM

2018-12-01T20:45:36Z

This commit adds an OOM notifier during rcutorture forward-progress testing. If this notifier is invoked, it dumps out some grace-period state to help debug the forward-progress problem. Signed-off-by: Paul E. McKenney