rcu: Force tick on for nohz_full CPUs not reaching quiescent states

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CPUs running for long time periods in the kernel in nohz_full mode
might leave the scheduling-clock interrupt disabled for then full
duration of their in-kernel execution.  This can (among other things)
delay grace periods.  This commit therefore forces the tick back on
for any nohz_full CPU that is failing to pass through a quiescent state
upon return from interrupt, which the resched_cpu() will induce.

Reported-by: Joel Fernandes <joel@joelfernandes.org>
[ paulmck: Clear ->rcu_forced_tick as reported by Joel Fernandes testing. ]
[ paulmck: Apply Joel Fernandes TICK_DEP_MASK_RCU->TICK_DEP_BIT_RCU fix. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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This commit is contained in:

Paul E. McKenney 2019-08-12 16:14:00 -07:00

parent 79ba7ff5a9

commit 66e4c33b51

2 changed files with 32 additions and 7 deletions

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38

kernel/rcu/tree.c

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1

kernel/rcu/tree.h

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