workers depend on local-wake-up, if a work function change its CPU, it will corrupt workqueue, disallow this behavior.
When set_cpus_allowed_ptr() is called from workqueue.c in worker_thread(), we clear the PF_WQ_WORKER before set_cpus_allowed_ptr() and set it back after. (rescuer thread has no PF_WQ_WORKER, skip this behavior) It prevents other/future BUGs like https://bugzilla.kernel.org/show_bug.cgi?id=47301. CC: tangchen <tangc...@cn.fujitsu.com> Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com> --- kernel/sched/core.c | 8 +++++--- kernel/workqueue.c | 10 +++++++++- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d325c4b..355d3cc 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5187,9 +5187,11 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) goto out; } - if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) { - ret = -EINVAL; - goto out; + if (unlikely(p->flags & PF_THREAD_BOUND)) { + if (WARN_ON_ONCE(p->flags & PF_WQ_WORKER) || p != current) { + ret = -EINVAL; + goto out; + } } do_set_cpus_allowed(p, new_mask); diff --git a/kernel/workqueue.c b/kernel/workqueue.c index ec882a6..c55884d 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1600,6 +1600,7 @@ __acquires(&gcwq->lock) struct global_cwq *gcwq = worker->pool->gcwq; struct task_struct *task = worker->task; + BUG_ON(task != current); while (true) { /* * The following call may fail, succeed or succeed @@ -1607,9 +1608,16 @@ __acquires(&gcwq->lock) * it races with cpu hotunplug operation. Verify * against GCWQ_DISASSOCIATED. */ - if (!(gcwq->flags & GCWQ_DISASSOCIATED)) + if (!(gcwq->flags & GCWQ_DISASSOCIATED)) { + if (!(worker->flags & WORKER_RESCUER)) + task->flags &= ~PF_WQ_WORKER; + set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); + if (!(worker->flags & WORKER_RESCUER)) + task->flags |= PF_WQ_WORKER; + } + spin_lock_irq(&gcwq->lock); if (gcwq->flags & GCWQ_DISASSOCIATED) return false; -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
