diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-01-08 14:35:52 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-02-23 15:14:40 -0800 |
| commit | ad7c946b35ad455417fdd4bc0e17deda4011841b (patch) | |
| tree | 8f78b9d52f74c2e4aed4acea5bbce6c96d5143d8 /kernel/rcu/srcutree.c | |
| parent | 65963d246147c46aafda2b04523d6dbe6c457e7c (diff) | |
rcu: Create RCU-specific workqueues with rescuers
RCU's expedited grace periods can participate in out-of-memory deadlocks
due to all available system_wq kthreads being blocked and there not being
memory available to create more. This commit prevents such deadlocks
by allocating an RCU-specific workqueue_struct at early boot time, and
providing it with a rescuer to ensure forward progress. This uses the
shiny new init_rescuer() function provided by Tejun (but indirectly).
This commit also causes SRCU to use this new RCU-specific
workqueue_struct. Note that SRCU's use of workqueues never blocks them
waiting for readers, so this should be safe from a forward-progress
viewpoint. Note that this moves SRCU from system_power_efficient_wq
to a normal workqueue. In the unlikely event that this results in
measurable degradation, a separate power-efficient workqueue will be
creates for SRCU.
Reported-by: Prateek Sood <prsood@codeaurora.org>
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/rcu/srcutree.c')
| -rw-r--r-- | kernel/rcu/srcutree.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 045b559b9f22..743d18379256 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -492,8 +492,7 @@ static bool srcu_queue_delayed_work_on(int cpu, struct workqueue_struct *wq, */ static void srcu_schedule_cbs_sdp(struct srcu_data *sdp, unsigned long delay) { - srcu_queue_delayed_work_on(sdp->cpu, system_power_efficient_wq, - &sdp->work, delay); + srcu_queue_delayed_work_on(sdp->cpu, rcu_gp_wq, &sdp->work, delay); } /* @@ -691,8 +690,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *sp, struct srcu_data *sdp, rcu_seq_state(sp->srcu_gp_seq) == SRCU_STATE_IDLE) { WARN_ON_ONCE(ULONG_CMP_GE(sp->srcu_gp_seq, sp->srcu_gp_seq_needed)); srcu_gp_start(sp); - queue_delayed_work(system_power_efficient_wq, &sp->work, - srcu_get_delay(sp)); + queue_delayed_work(rcu_gp_wq, &sp->work, srcu_get_delay(sp)); } spin_unlock_irqrestore_rcu_node(sp, flags); } @@ -1225,7 +1223,7 @@ static void srcu_reschedule(struct srcu_struct *sp, unsigned long delay) spin_unlock_irq_rcu_node(sp); if (pushgp) - queue_delayed_work(system_power_efficient_wq, &sp->work, delay); + queue_delayed_work(rcu_gp_wq, &sp->work, delay); } /* |