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authorPeter Zijlstra <peterz@infradead.org>2016-06-16 14:38:42 +0200
committerTejun Heo <tj@kernel.org>2016-06-16 15:37:05 -0400
commitd945b5e9f0e35cb56a3783d849b5f0f37da0a7f1 (patch)
tree6314d7df35841c4582ab22f7602b19a4e03cc551 /kernel
parentdb06d759d6cf903aeda8c107fd3abd366dd80200 (diff)
workqueue: Fix setting affinity of unbound worker threads
With commit e9d867a67fd03ccc ("sched: Allow per-cpu kernel threads to run on online && !active"), __set_cpus_allowed_ptr() expects that only strict per-cpu kernel threads can have affinity to an online CPU which is not yet active. This assumption is currently broken in the CPU_ONLINE notification handler for the workqueues where restore_unbound_workers_cpumask() calls set_cpus_allowed_ptr() when the first cpu in the unbound worker's pool->attr->cpumask comes online. Since set_cpus_allowed_ptr() is called with pool->attr->cpumask in which only one CPU is online which is not yet active, we get the following WARN_ON during an CPU online operation. ------------[ cut here ]------------ WARNING: CPU: 40 PID: 248 at kernel/sched/core.c:1166 __set_cpus_allowed_ptr+0x228/0x2e0 Modules linked in: CPU: 40 PID: 248 Comm: cpuhp/40 Not tainted 4.6.0-autotest+ #4 <..snip..> Call Trace: [c000000f273ff920] [c00000000010493c] __set_cpus_allowed_ptr+0x2cc/0x2e0 (unreliable) [c000000f273ffac0] [c0000000000ed4b0] workqueue_cpu_up_callback+0x2c0/0x470 [c000000f273ffb70] [c0000000000f5c58] notifier_call_chain+0x98/0x100 [c000000f273ffbc0] [c0000000000c5ed0] __cpu_notify+0x70/0xe0 [c000000f273ffc00] [c0000000000c6028] notify_online+0x38/0x50 [c000000f273ffc30] [c0000000000c5214] cpuhp_invoke_callback+0x84/0x250 [c000000f273ffc90] [c0000000000c562c] cpuhp_up_callbacks+0x5c/0x120 [c000000f273ffce0] [c0000000000c64d4] cpuhp_thread_fun+0x184/0x1c0 [c000000f273ffd20] [c0000000000fa050] smpboot_thread_fn+0x290/0x2a0 [c000000f273ffd80] [c0000000000f45b0] kthread+0x110/0x130 [c000000f273ffe30] [c000000000009570] ret_from_kernel_thread+0x5c/0x6c ---[ end trace 00f1456578b2a3b2 ]--- This patch fixes this by limiting the mask to the intersection of the pool affinity and online CPUs. Changelog-cribbed-from: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/workqueue.c6
1 files changed, 1 insertions, 5 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index e1c0e996b5ae..97e7b793df35 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4600,15 +4600,11 @@ static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
return;
- /* is @cpu the only online CPU? */
cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
- if (cpumask_weight(&cpumask) != 1)
- return;
/* as we're called from CPU_ONLINE, the following shouldn't fail */
for_each_pool_worker(worker, pool)
- WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
- pool->attrs->cpumask) < 0);
+ WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0);
}
/*