Merge branch 'for-4.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue fixes from Tejun Heo:

 - Lai's hotplug simplifications inadvertently fix a possible deadlock
   involving cpuset and workqueue

 - CPU isolation fix which was reverted due to the changes in the
   housekeeping code resurrected

 - A trivial unused include removal

* 'for-4.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: remove unneeded kallsyms include
  workqueue/hotplug: remove the workaround in rebind_workers()
  workqueue/hotplug: simplify workqueue_offline_cpu()
  workqueue: respect isolated cpus when queueing an unbound work
  main: kernel_start: move housekeeping_init() before workqueue_init_early()

diff --git a/init/main.c b/init/main.c
index dfec3809e7404f9658d51a20aae3869cd7aab9c3..e96e3a14533cda199963fe96b97dc78779c66037 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -588,6 +588,12 @@ asmlinkage __visible void __init start_kernel(void)
                local_irq_disable();
        radix_tree_init();
 
+       /*
+        * Set up housekeeping before setting up workqueues to allow the unbound
+        * workqueue to take non-housekeeping into account.
+        */
+       housekeeping_init();
+
        /*
         * Allow workqueue creation and work item queueing/cancelling
         * early.  Work item execution depends on kthreads and starts after
@@ -605,7 +611,6 @@ asmlinkage __visible void __init start_kernel(void)
        early_irq_init();
        init_IRQ();
        tick_init();
-       housekeeping_init();
        rcu_init_nohz();
        init_timers();
        hrtimers_init();

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 8fdb710bfdd732fc3e6bfaa3110264de70c9af1d..43d18cb46308385865d14ce40906c4646d378063 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -38,7 +38,6 @@
 #include <linux/hardirq.h>
 #include <linux/mempolicy.h>
 #include <linux/freezer.h>
-#include <linux/kallsyms.h>
 #include <linux/debug_locks.h>
 #include <linux/lockdep.h>
 #include <linux/idr.h>
@@ -48,6 +47,7 @@
 #include <linux/nodemask.h>
 #include <linux/moduleparam.h>
 #include <linux/uaccess.h>
+#include <linux/sched/isolation.h>
 
 #include "workqueue_internal.h"
 
@@ -1634,7 +1634,7 @@ static void worker_enter_idle(struct worker *worker)
                mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
 
        /*
-        * Sanity check nr_running.  Because wq_unbind_fn() releases
+        * Sanity check nr_running.  Because unbind_workers() releases
         * pool->lock between setting %WORKER_UNBOUND and zapping
         * nr_running, the warning may trigger spuriously.  Check iff
         * unbind is not in progress.
@@ -4510,9 +4510,8 @@ void show_workqueue_state(void)
  * cpu comes back online.
  */
 
-static void wq_unbind_fn(struct work_struct *work)
+static void unbind_workers(int cpu)
 {
-       int cpu = smp_processor_id();
        struct worker_pool *pool;
        struct worker *worker;
 
@@ -4589,16 +4588,6 @@ static void rebind_workers(struct worker_pool *pool)
 
        spin_lock_irq(&pool->lock);
 
-       /*
-        * XXX: CPU hotplug notifiers are weird and can call DOWN_FAILED
-        * w/o preceding DOWN_PREPARE.  Work around it.  CPU hotplug is
-        * being reworked and this can go away in time.
-        */
-       if (!(pool->flags & POOL_DISASSOCIATED)) {
-               spin_unlock_irq(&pool->lock);
-               return;
-       }
-
        pool->flags &= ~POOL_DISASSOCIATED;
 
        for_each_pool_worker(worker, pool) {
@@ -4709,12 +4698,13 @@ int workqueue_online_cpu(unsigned int cpu)
 
 int workqueue_offline_cpu(unsigned int cpu)
 {
-       struct work_struct unbind_work;
        struct workqueue_struct *wq;
 
        /* unbinding per-cpu workers should happen on the local CPU */
-       INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn);
-       queue_work_on(cpu, system_highpri_wq, &unbind_work);
+       if (WARN_ON(cpu != smp_processor_id()))
+               return -1;
+
+       unbind_workers(cpu);
 
        /* update NUMA affinity of unbound workqueues */
        mutex_lock(&wq_pool_mutex);
@@ -4722,9 +4712,6 @@ int workqueue_offline_cpu(unsigned int cpu)
                wq_update_unbound_numa(wq, cpu, false);
        mutex_unlock(&wq_pool_mutex);
 
-       /* wait for per-cpu unbinding to finish */
-       flush_work(&unbind_work);
-       destroy_work_on_stack(&unbind_work);
        return 0;
 }
 
@@ -4957,6 +4944,10 @@ int workqueue_set_unbound_cpumask(cpumask_var_t cpumask)
        if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL))
                return -ENOMEM;
 
+       /*
+        * Not excluding isolated cpus on purpose.
+        * If the user wishes to include them, we allow that.
+        */
        cpumask_and(cpumask, cpumask, cpu_possible_mask);
        if (!cpumask_empty(cpumask)) {
                apply_wqattrs_lock();
@@ -5555,7 +5546,7 @@ int __init workqueue_init_early(void)
        WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
 
        BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
-       cpumask_copy(wq_unbound_cpumask, cpu_possible_mask);
+       cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(HK_FLAG_DOMAIN));
 
        pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);