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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-01-09 01:35:52 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-02-24 02:14:40 +0300 |
| commit | ad7c946b35ad455417fdd4bc0e17deda4011841b (patch) | |
| tree | 8f78b9d52f74c2e4aed4acea5bbce6c96d5143d8 /kernel/rcu/tree.c | |
| parent | 65963d246147c46aafda2b04523d6dbe6c457e7c (diff) | |
| download | linux-ad7c946b35ad455417fdd4bc0e17deda4011841b.tar.xz | |
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/tree.c')
| -rw-r--r-- | kernel/rcu/tree.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 99d404c6bbbb..2a734692a581 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4167,6 +4167,8 @@ static void __init rcu_dump_rcu_node_tree(struct rcu_state *rsp) pr_cont("\n"); } +struct workqueue_struct *rcu_gp_wq; + void __init rcu_init(void) { int cpu; @@ -4193,6 +4195,10 @@ void __init rcu_init(void) rcu_cpu_starting(cpu); rcutree_online_cpu(cpu); } + + /* Create workqueue for expedited GPs and for Tree SRCU. */ + rcu_gp_wq = alloc_workqueue("rcu_gp", WQ_MEM_RECLAIM, 0); + WARN_ON(!rcu_gp_wq); } #include "tree_exp.h" |