linux/kernel/workqueue.c, branch v3.16

workqueue: zero cpumask of wq_numa_possible_cpumask on init

2014-07-07T13:56:48Z

When hot-adding and onlining CPU, kernel panic occurs, showing following call trace. BUG: unable to handle kernel paging request at 0000000000001d08 IP: [] __alloc_pages_nodemask+0x9d/0xb10 PGD 0 Oops: 0000 [#1] SMP ... Call Trace: [] ? cpumask_next_and+0x35/0x50 [] ? find_busiest_group+0x113/0x8f0 [] ? deactivate_slab+0x349/0x3c0 [] new_slab+0x91/0x300 [] __slab_alloc+0x2bb/0x482 [] ? copy_process.part.25+0xfc/0x14c0 [] ? load_balance+0x218/0x890 [] ? sched_clock+0x9/0x10 [] ? trace_clock_local+0x9/0x10 [] kmem_cache_alloc_node+0x8c/0x200 [] copy_process.part.25+0xfc/0x14c0 [] ? trace_buffer_unlock_commit+0x4d/0x60 [] ? kthread_create_on_node+0x140/0x140 [] do_fork+0xbc/0x360 [] kernel_thread+0x26/0x30 [] kthreadd+0x2c2/0x300 [] ? kthread_create_on_cpu+0x60/0x60 [] ret_from_fork+0x7c/0xb0 [] ? kthread_create_on_cpu+0x60/0x60 In my investigation, I found the root cause is wq_numa_possible_cpumask. All entries of wq_numa_possible_cpumask is allocated by alloc_cpumask_var_node(). And these entries are used without initializing. So these entries have wrong value. When hot-adding and onlining CPU, wq_update_unbound_numa() is called. wq_update_unbound_numa() calls alloc_unbound_pwq(). And alloc_unbound_pwq() calls get_unbound_pool(). In get_unbound_pool(), worker_pool->node is set as follow: 3592 /* if cpumask is contained inside a NUMA node, we belong to that node */ 3593 if (wq_numa_enabled) { 3594 for_each_node(node) { 3595 if (cpumask_subset(pool->attrs->cpumask, 3596 wq_numa_possible_cpumask[node])) { 3597 pool->node = node; 3598 break; 3599 } 3600 } 3601 } But wq_numa_possible_cpumask[node] does not have correct cpumask. So, wrong node is selected. As a result, kernel panic occurs. By this patch, all entries of wq_numa_possible_cpumask are allocated by zalloc_cpumask_var_node to initialize them. And the panic disappeared. Signed-off-by: Yasuaki Ishimatsu Reviewed-by: Lai Jiangshan Signed-off-by: Tejun Heo Cc: stable@vger.kernel.org Fixes: bce903809ab3 ("workqueue: add wq_numa_tbl_len and wq_numa_possible_cpumask[]")

workqueue: fix dev_set_uevent_suppress() imbalance

2014-06-23T18:40:49Z

Uevents are suppressed during attributes registration, but never restored, so kobject_uevent() does nothing. Signed-off-by: Maxime Bizon Signed-off-by: Tejun Heo Cc: stable@vger.kernel.org Fixes: 226223ab3c4118ddd10688cc2c131135848371ab

Merge branch 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2014-06-09T21:56:49Z

Pull workqueue updates from Tejun Heo: "Lai simplified worker destruction path and internal workqueue locking and there are some other minor changes. Except for the removal of some long-deprecated interfaces which haven't had any in-kernel user for quite a while, there shouldn't be any difference to workqueue users" * 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: kernel/workqueue.c: pr_warning/pr_warn & printk/pr_info workqueue: remove the confusing POOL_FREEZING workqueue: rename first_worker() to first_idle_worker() workqueue: remove unused work_clear_pending() workqueue: remove unused WORK_CPU_END workqueue: declare system_highpri_wq workqueue: use generic attach/detach routine for rescuers workqueue: separate pool-attaching code out from create_worker() workqueue: rename manager_mutex to attach_mutex workqueue: narrow the protection range of manager_mutex workqueue: convert worker_idr to worker_ida workqueue: separate iteration role from worker_idr workqueue: destroy worker directly in the idle timeout handler workqueue: async worker destruction workqueue: destroy_worker() should destroy idle workers only workqueue: use manager lock only to protect worker_idr workqueue: Remove deprecated system_nrt[_freezable]_wq workqueue: Remove deprecated flush[_delayed]_work_sync() kernel/workqueue.c: pr_warning/pr_warn & printk/pr_info workqueue: simplify wq_update_unbound_numa() by jumping to use_dfl_pwq if the target cpumask equals wq's

kernel/workqueue.c: pr_warning/pr_warn & printk/pr_info

2014-05-28T14:22:34Z

This commit did an incorrect printk->pr_info conversion. If we were converting to pr_info() we should lose the log_level parameter. The problem is that this is called (indirectly) by show_regs_print_info(), which is called with various log_levels (from _INFO clear to _EMERG). So we leave it as a printk() call so the desired log_level is applied. Not a full revert, as the other half of the patch is correct. Signed-off-by: Valdis Kletnieks Signed-off-by: Tejun Heo

workqueue: remove the confusing POOL_FREEZING

2014-05-22T15:35:51Z

Currently, the global freezing state is propagated to worker_pools via POOL_FREEZING and then to each workqueue; however, the middle step - propagation through worker_pools - can be skipped as long as one or more max_active adjustments happens for each workqueue after the update to the global state is visible. The global workqueue freezing state and the max_active adjustments during workqueue creation and [un]freezing are serialized with wq_pool_mutex, so it's trivial to guarantee that max_actives stay in sync with global freezing state. POOL_FREEZING is unnecessary and makes the code more confusing and complicates freeze_workqueues_begin() and thaw_workqueues() by requiring them to walk through all pools. Remove POOL_FREEZING and use workqueue_freezing directly instead. tj: Description and comment updates. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: rename first_worker() to first_idle_worker()

2014-05-22T15:35:51Z

first_worker() actually returns the first idle workers, the name first_idle_worker() which is self-commnet will be better. All the callers of first_worker() expect it returns an idle worker, the name first_idle_worker() with "idle" notation makes reviewers happier. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

Merge tag 'v3.15-rc6' into sched/core, to pick up the latest fixes

2014-05-22T08:28:56Z

Signed-off-by: Ingo Molnar

workqueue: use generic attach/detach routine for rescuers

2014-05-20T14:59:32Z

There are several problems with the code that rescuers use to bind themselve to the target pool's cpumask. 1) It is very different from how the normal workers bind to cpumask, increasing code complexity and maintenance overhead. 2) The code of cpu-binding for rescuers is complicated. 3) If one or more cpu hotplugs happen while a rescuer is processing its scheduled work items, the rescuer may not stay bound to the cpumask of the pool. This is an allowed behavior, but is still hairy. It will be better if the cpumask of the rescuer is always kept synchronized with the pool across cpu hotplugs. Using generic attach/detach routine will solve the above problems and results in much simpler code. tj: Minor description updates. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: separate pool-attaching code out from create_worker()

2014-05-20T14:59:32Z

Currently, the code to attach a new worker to its pool is embedded in create_worker(). Separating this code out will make the codes clearer and will allow rescuers to share the code path later. tj: Description and comment updates. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: rename manager_mutex to attach_mutex

2014-05-20T14:59:32Z

manager_mutex is only used to protect the attaching for the pool and the pool->workers list. It protects the pool->workers and operations based on this list, such as: cpu-binding for the workers in the pool->workers the operations to set/clear WORKER_UNBOUND So let's rename manager_mutex to attach_mutex to better reflect its role. This patch is a pure rename. tj: Minor command and description updates. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo