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authorLinus Torvalds <torvalds@linux-foundation.org>2017-07-31 13:37:28 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-31 13:37:28 -0700
commitff2620f778b1942eea40bd43773094dbc0e76c7e (patch)
tree8f2aafbbdc2139380b1a166942c7ec7ea597a14a /kernel
parent3dcc4c7d422ce5f2887a021190234a683f8f8cb1 (diff)
parent1ad0f0a7aa1bf3bd42dcd108a96713d255eacd9f (diff)
downloadop-kernel-dev-ff2620f778b1942eea40bd43773094dbc0e76c7e.zip
op-kernel-dev-ff2620f778b1942eea40bd43773094dbc0e76c7e.tar.gz
Merge branch 'for-4.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue fixes from Tejun Heo: "Two notable fixes. - While adding NUMA affinity support to unbound workqueues, the assumption that an unbound workqueue with max_active == 1 is ordered was broken. The plan was to use explicit alloc_ordered_workqueue() for those cases. Unfortunately, I forgot to update the documentation properly and we grew a handful of use cases which depend on that assumption. While we want to convert them to alloc_ordered_workqueue(), we don't really lose anything by enforcing ordered execution on unbound max_active == 1 workqueues and it doesn't make sense to risk subtle bugs. Restore the assumption. - Workqueue assumes that CPU <-> NUMA node mapping remains static. This is a general assumption - we don't have any synchronization mechanism around CPU <-> node mapping. Unfortunately, powerpc may change the mapping dynamically leading to crashes. Michael added a workaround so that we at least don't crash while powerpc hotplug code gets updated" * 'for-4.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Work around edge cases for calc of pool's cpumask workqueue: implicit ordered attribute should be overridable workqueue: restore WQ_UNBOUND/max_active==1 to be ordered
Diffstat (limited to 'kernel')
-rw-r--r--kernel/workqueue.c30
1 files changed, 26 insertions, 4 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index a86688f..ca937b0 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3577,6 +3577,13 @@ static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node,
/* yeap, return possible CPUs in @node that @attrs wants */
cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]);
+
+ if (cpumask_empty(cpumask)) {
+ pr_warn_once("WARNING: workqueue cpumask: online intersect > "
+ "possible intersect\n");
+ return false;
+ }
+
return !cpumask_equal(cpumask, attrs->cpumask);
use_dfl:
@@ -3744,8 +3751,12 @@ static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
return -EINVAL;
/* creating multiple pwqs breaks ordering guarantee */
- if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
- return -EINVAL;
+ if (!list_empty(&wq->pwqs)) {
+ if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
+ return -EINVAL;
+
+ wq->flags &= ~__WQ_ORDERED;
+ }
ctx = apply_wqattrs_prepare(wq, attrs);
if (!ctx)
@@ -3929,6 +3940,16 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
struct workqueue_struct *wq;
struct pool_workqueue *pwq;
+ /*
+ * Unbound && max_active == 1 used to imply ordered, which is no
+ * longer the case on NUMA machines due to per-node pools. While
+ * alloc_ordered_workqueue() is the right way to create an ordered
+ * workqueue, keep the previous behavior to avoid subtle breakages
+ * on NUMA.
+ */
+ if ((flags & WQ_UNBOUND) && max_active == 1)
+ flags |= __WQ_ORDERED;
+
/* see the comment above the definition of WQ_POWER_EFFICIENT */
if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
flags |= WQ_UNBOUND;
@@ -4119,13 +4140,14 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
struct pool_workqueue *pwq;
/* disallow meddling with max_active for ordered workqueues */
- if (WARN_ON(wq->flags & __WQ_ORDERED))
+ if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
return;
max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
mutex_lock(&wq->mutex);
+ wq->flags &= ~__WQ_ORDERED;
wq->saved_max_active = max_active;
for_each_pwq(pwq, wq)
@@ -5253,7 +5275,7 @@ int workqueue_sysfs_register(struct workqueue_struct *wq)
* attributes breaks ordering guarantee. Disallow exposing ordered
* workqueues.
*/
- if (WARN_ON(wq->flags & __WQ_ORDERED))
+ if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
return -EINVAL;
wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
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