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authorTejun Heo <tj@kernel.org>2013-09-05 12:30:04 -0400
committerTejun Heo <tj@kernel.org>2013-11-22 18:14:02 -0500
commit8a2b75384444488fc4f2cbb9f0921b6a0794838f (patch)
treec4b39daad8de264be08beec77621048e9b9fb9ed
parent91151228065354a050fd0d190aefdd662a0580aa (diff)
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workqueue: fix ordered workqueues in NUMA setups
An ordered workqueue implements execution ordering by using single pool_workqueue with max_active == 1. On a given pool_workqueue, work items are processed in FIFO order and limiting max_active to 1 enforces the queued work items to be processed one by one. Unfortunately, 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues") accidentally broke this guarantee by applying NUMA affinity to ordered workqueues too. On NUMA setups, an ordered workqueue would end up with separate pool_workqueues for different nodes. Each pool_workqueue still limits max_active to 1 but multiple work items may be executed concurrently and out of order depending on which node they are queued to. Fix it by using dedicated ordered_wq_attrs[] when creating ordered workqueues. The new attrs match the unbound ones except that no_numa is always set thus forcing all NUMA nodes to share the default pool_workqueue. While at it, add sanity check in workqueue creation path which verifies that an ordered workqueues has only the default pool_workqueue. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Libin <huawei.libin@huawei.com> Cc: stable@vger.kernel.org Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
-rw-r--r--kernel/workqueue.c24
1 files changed, 22 insertions, 2 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index f8942429268b..bbb5e9832d85 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -305,6 +305,9 @@ static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
/* I: attributes used when instantiating standard unbound pools on demand */
static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
+/* I: attributes used when instantiating ordered pools on demand */
+static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS];
+
struct workqueue_struct *system_wq __read_mostly;
EXPORT_SYMBOL(system_wq);
struct workqueue_struct *system_highpri_wq __read_mostly;
@@ -4107,7 +4110,7 @@ out_unlock:
static int alloc_and_link_pwqs(struct workqueue_struct *wq)
{
bool highpri = wq->flags & WQ_HIGHPRI;
- int cpu;
+ int cpu, ret;
if (!(wq->flags & WQ_UNBOUND)) {
wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);
@@ -4127,6 +4130,13 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq)
mutex_unlock(&wq->mutex);
}
return 0;
+ } else if (wq->flags & __WQ_ORDERED) {
+ ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
+ /* there should only be single pwq for ordering guarantee */
+ WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node ||
+ wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),
+ "ordering guarantee broken for workqueue %s\n", wq->name);
+ return ret;
} else {
return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
}
@@ -5052,13 +5062,23 @@ static int __init init_workqueues(void)
}
}
- /* create default unbound wq attrs */
+ /* create default unbound and ordered wq attrs */
for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
struct workqueue_attrs *attrs;
BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
attrs->nice = std_nice[i];
unbound_std_wq_attrs[i] = attrs;
+
+ /*
+ * An ordered wq should have only one pwq as ordering is
+ * guaranteed by max_active which is enforced by pwqs.
+ * Turn off NUMA so that dfl_pwq is used for all nodes.
+ */
+ BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
+ attrs->nice = std_nice[i];
+ attrs->no_numa = true;
+ ordered_wq_attrs[i] = attrs;
}
system_wq = alloc_workqueue("events", 0, 0);