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authorJoe Lawrence <joe.lawrence@stratus.com>2014-10-05 13:24:21 -0400
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-10-06 05:57:43 -0700
commit789cbbeca4eb7141cbd748ee93772471101b507b (patch)
tree357a38595c99840947212b6ec89a7a6d4ada2aee /kernel/workqueue.c
parentc98fed9fc6a7449affd941d8a8e9fcb0c72977d6 (diff)
downloadop-kernel-dev-789cbbeca4eb7141cbd748ee93772471101b507b.zip
op-kernel-dev-789cbbeca4eb7141cbd748ee93772471101b507b.tar.gz
workqueue: Add quiescent state between work items
Similar to the stop_machine deadlock scenario on !PREEMPT kernels addressed in b22ce2785d97 "workqueue: cond_resched() after processing each work item", kworker threads requeueing back-to-back with zero jiffy delay can stall RCU. The cond_resched call introduced in that fix will yield only iff there are other higher priority tasks to run, so force a quiescent RCU state between work items. Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Link: https://lkml.kernel.org/r/20140926105227.01325697@jlaw-desktop.mno.stratus.com Link: https://lkml.kernel.org/r/20140929115445.40221d8e@jlaw-desktop.mno.stratus.com Fixes: b22ce2785d97 ("workqueue: cond_resched() after processing each work item") Cc: <stable@vger.kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r--kernel/workqueue.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 5dbe22a..345bec9 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2043,8 +2043,10 @@ __acquires(&pool->lock)
* kernels, where a requeueing work item waiting for something to
* happen could deadlock with stop_machine as such work item could
* indefinitely requeue itself while all other CPUs are trapped in
- * stop_machine.
+ * stop_machine. At the same time, report a quiescent RCU state so
+ * the same condition doesn't freeze RCU.
*/
+ rcu_note_voluntary_context_switch(current);
cond_resched();
spin_lock_irq(&pool->lock);
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