user/sven/linux.git/kernel/workqueue.c, branch v3.10.32

workqueue: fix ordered workqueues in NUMA setups

2013-12-04T18:57:16Z

commit 8a2b75384444488fc4f2cbb9f0921b6a0794838f upstream. An ordered workqueue implements execution ordering by using single pool_workqueue with max_active == 1. On a given pool_workqueue, work items are processed in FIFO order and limiting max_active to 1 enforces the queued work items to be processed one by one. Unfortunately, 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues") accidentally broke this guarantee by applying NUMA affinity to ordered workqueues too. On NUMA setups, an ordered workqueue would end up with separate pool_workqueues for different nodes. Each pool_workqueue still limits max_active to 1 but multiple work items may be executed concurrently and out of order depending on which node they are queued to. Fix it by using dedicated ordered_wq_attrs[] when creating ordered workqueues. The new attrs match the unbound ones except that no_numa is always set thus forcing all NUMA nodes to share the default pool_workqueue. While at it, add sanity check in workqueue creation path which verifies that an ordered workqueues has only the default pool_workqueue. Signed-off-by: Tejun Heo Reported-by: Libin Cc: Lai Jiangshan Signed-off-by: Greg Kroah-Hartman

workqueue: cond_resched() after processing each work item

2013-09-08T05:09:58Z

commit b22ce2785d97423846206cceec4efee0c4afd980 upstream. If !PREEMPT, a kworker running work items back to back can hog CPU. This becomes dangerous when a self-requeueing work item which is waiting for something to happen races against stop_machine. Such self-requeueing work item would requeue itself indefinitely hogging the kworker and CPU it's running on while stop_machine would wait for that CPU to enter stop_machine while preventing anything else from happening on all other CPUs. The two would deadlock. Jamie Liu reports that this deadlock scenario exists around scsi_requeue_run_queue() and libata port multiplier support, where one port may exclude command processing from other ports. With the right timing, scsi_requeue_run_queue() can end up requeueing itself trying to execute an IO which is asked to be retried while another device has an exclusive access, which in turn can't make forward progress due to stop_machine. Fix it by invoking cond_resched() after executing each work item. Signed-off-by: Tejun Heo Reported-by: Jamie Liu References: http://thread.gmane.org/gmane.linux.kernel/1552567 Signed-off-by: Greg Kroah-Hartman

workqueue: copy workqueue_attrs with all fields

2013-08-12T01:35:25Z

commit 2865a8fb44cc32420407362cbda80c10fa09c6b2 upstream. $echo '0' > /sys/bus/workqueue/devices/xxx/numa $cat /sys/bus/workqueue/devices/xxx/numa I got 1. It should be 0, the reason is copy_workqueue_attrs() called in apply_workqueue_attrs() doesn't copy no_numa field. Fix it by making copy_workqueue_attrs() copy ->no_numa too. This would also make get_unbound_pool() set a pool's ->no_numa attribute according to the workqueue attributes used when the pool was created. While harmelss, as ->no_numa isn't a pool attribute, this is a bit confusing. Clear it explicitly. tj: Updated description and comments a bit. Signed-off-by: Shaohua Li Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

workqueue: don't perform NUMA-aware allocations on offline nodes in wq_numa_init()

2013-05-15T21:24:24Z

wq_numa_init() builds per-node cpumasks which are later used to make unbound workqueues NUMA-aware. The cpumasks are allocated using alloc_cpumask_var_node() for all possible nodes. Unfortunately, on machines with off-line nodes, this leads to NUMA-aware allocations on existing bug offline nodes, which in turn triggers BUG in the memory allocation code. Fix it by using NUMA_NO_NODE for cpumask allocations for offline nodes. kernel BUG at include/linux/gfp.h:323! invalid opcode: 0000 [#1] SMP Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0+ #1 Hardware name: ProLiant BL465c G7, BIOS A19 12/10/2011 task: ffff880234608000 ti: ffff880234602000 task.ti: ffff880234602000 RIP: 0010:[] [] new_slab+0x2ad/0x340 RSP: 0000:ffff880234603bf8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff880237404b40 RCX: 00000000000000d0 RDX: 0000000000000001 RSI: 0000000000000003 RDI: 00000000002052d0 RBP: ffff880234603c28 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000001 R11: ffffffff812e3aa8 R12: 0000000000000001 R13: ffff8802378161c0 R14: 0000000000030027 R15: 00000000000040d0 FS: 0000000000000000(0000) GS:ffff880237800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: ffff88043fdff000 CR3: 00000000018d5000 CR4: 00000000000007f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Stack: ffff880234603c28 0000000000000001 00000000000000d0 ffff8802378161c0 ffff880237404b40 ffff880237404b40 ffff880234603d28 ffffffff815edba1 ffff880237816140 0000000000000000 ffff88023740e1c0 Call Trace: [] __slab_alloc+0x330/0x4f2 [] kmem_cache_alloc_node_trace+0xa5/0x200 [] alloc_cpumask_var_node+0x28/0x90 [] wq_numa_init+0x10d/0x1be [] init_workqueues+0x64/0x341 [] do_one_initcall+0xea/0x1a0 [] kernel_init_freeable+0xb7/0x1ec [] kernel_init+0xe/0xf0 [] ret_from_fork+0x7c/0xb0 Code: 45 84 ac 00 00 00 f0 41 80 4d 00 40 e9 f6 fe ff ff 66 0f 1f 84 00 00 00 00 00 e8 eb 4b ff ff 49 89 c5 e9 05 fe ff ff <0f> 0b 4c 8b 73 38 44 89 ff 81 cf 00 00 20 00 4c 89 f6 48 c1 ee Signed-off-by: Tejun Heo Reported-and-Tested-by: Lingzhu Xiang

workqueue: Make schedule_work() available again to non GPL modules

2013-05-14T18:52:51Z

Commit 8425e3d5bdbe ("workqueue: inline trivial wrappers") changed schedule_work() and schedule_delayed_work() to inline wrappers, but these rely on some symbols that are EXPORT_SYMBOL_GPL, while the original functions were EXPORT_SYMBOL. This has the effect of changing the licensing requirement for these functions and making them unavailable to non GPL modules. Make them available again by removing the restriction on the required symbols. Signed-off-by: Marc Dionne Signed-off-by: Tejun Heo

workqueue: correct handling of the pool spin_lock

2013-05-14T18:48:15Z

When we fail to mutex_trylock(), we release the pool spin_lock and do mutex_lock(). After that, we should regrab the pool spin_lock, but, regrabbing is missed in current code. So correct it. Cc: Lai Jiangshan Signed-off-by: Joonsoo Kim Signed-off-by: Tejun Heo

workqueue: workqueue_congested() shouldn't translate WORK_CPU_UNBOUND into node number

2013-05-10T18:10:17Z

df2d5ae499 ("workqueue: map an unbound workqueues to multiple per-node pool_workqueues") made unbound workqueues to map to multiple per-node pool_workqueues and accordingly updated workqueue_contested() so that, for unbound workqueues, it maps the specified @cpu to the NUMA node number to obtain the matching pool_workqueue to query the congested state. Before this change, workqueue_congested() ignored @cpu for unbound workqueues as there was only one pool_workqueue and some users (fscache) called it with WORK_CPU_UNBOUND. After the commit, this causes the following oops as WORK_CPU_UNBOUND gets translated to garbage by cpu_to_node(). BUG: unable to handle kernel paging request at ffff8803598d98b8 IP: [] unbound_pwq_by_node+0xa1/0xfa PGD 2421067 PUD 0 Oops: 0000 [#1] SMP CPU: 1 PID: 2689 Comm: cat Tainted: GF 3.9.0-fsdevel+ #4 task: ffff88003d801040 ti: ffff880025806000 task.ti: ffff880025806000 RIP: 0010:[] [] unbound_pwq_by_node+0xa1/0xfa RSP: 0018:ffff880025807ad8 EFLAGS: 00010202 RAX: 0000000000000001 RBX: ffff8800388a2400 RCX: 0000000000000003 RDX: ffff880025807fd8 RSI: ffffffff81a31420 RDI: ffff88003d8016e0 RBP: ffff880025807ae8 R08: ffff88003d801730 R09: ffffffffa00b4898 R10: ffffffff81044217 R11: ffff88003d801040 R12: 0000000064206e97 R13: ffff880036059d98 R14: ffff880038cc8080 R15: ffff880038cc82d0 FS: 00007f21afd9c740(0000) GS:ffff88003d100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: ffff8803598d98b8 CR3: 000000003df49000 CR4: 00000000000007e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Stack: ffff8800388a2400 0000000000000002 ffff880025807b18 ffffffff810442ce ffffffff81044217 ffff880000000002 ffff8800371b4080 ffff88003d112ec0 ffff880025807b38 ffffffffa00810b0 ffff880036059d88 ffff880036059be8 Call Trace: [] workqueue_congested+0xb7/0x12c [] fscache_enqueue_object+0xb2/0xe8 [fscache] [] __fscache_acquire_cookie+0x3b9/0x56c [fscache] [] nfs_fscache_set_inode_cookie+0xee/0x132 [nfs] [] do_open+0x9/0xd [nfs] [] do_dentry_open+0x175/0x24b [] finish_open+0x41/0x51 Fix it by using smp_processor_id() if @cpu is WORK_CPU_UNBOUND. Signed-off-by: Tejun Heo Reported-by: David Howells Tested-and-Acked-by: David Howells

workqueue: include workqueue info when printing debug dump of a worker task

2013-05-01T00:04:02Z

One of the problems that arise when converting dedicated custom threadpool to workqueue is that the shared worker pool used by workqueue anonimizes each worker making it more difficult to identify what the worker was doing on which target from the output of sysrq-t or debug dump from oops, BUG() and friends. This patch implements set_worker_desc() which can be called from any workqueue work function to set its description. When the worker task is dumped for whatever reason - sysrq-t, WARN, BUG, oops, lockdep assertion and so on - the description will be printed out together with the workqueue name and the worker function pointer. The printing side is implemented by print_worker_info() which is called from functions in task dump paths - sched_show_task() and dump_stack_print_info(). print_worker_info() can be safely called on any task in any state as long as the task struct itself is accessible. It uses probe_*() functions to access worker fields. It may print garbage if something went very wrong, but it wouldn't cause (another) oops. The description is currently limited to 24bytes including the terminating \0. worker->desc_valid and workder->desc[] are added and the 64 bytes marker which was already incorrect before adding the new fields is moved to the correct position. Here's an example dump with writeback updated to set the bdi name as worker desc. Hardware name: Bochs Modules linked in: Pid: 7, comm: kworker/u9:0 Not tainted 3.9.0-rc1-work+ #1 Workqueue: writeback bdi_writeback_workfn (flush-8:0) ffffffff820a3ab0 ffff88000f6e9cb8 ffffffff81c61845 ffff88000f6e9cf8 ffffffff8108f50f 0000000000000000 0000000000000000 ffff88000cde16b0 ffff88000cde1aa8 ffff88001ee19240 ffff88000f6e9fd8 ffff88000f6e9d08 Call Trace: [] dump_stack+0x19/0x1b [] warn_slowpath_common+0x7f/0xc0 [] warn_slowpath_null+0x1a/0x20 [] bdi_writeback_workfn+0x2a0/0x3b0 ... Signed-off-by: Tejun Heo Cc: Peter Zijlstra Cc: Ingo Molnar Acked-by: Jan Kara Cc: Oleg Nesterov Cc: Jens Axboe Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

workqueue: use kmem_cache_free() instead of kfree()

2013-04-09T18:33:40Z

memory allocated by kmem_cache_alloc() should be freed using kmem_cache_free(), not kfree(). Signed-off-by: Wei Yongjun Signed-off-by: Tejun Heo

workqueue: avoid false negative WARN_ON() in destroy_workqueue()

2013-04-04T14:54:01Z

destroy_workqueue() performs several sanity checks before proceeding with destruction of a workqueue. One of the checks verifies that refcnt of each pwq (pool_workqueue) is over 1 as at that point there should be no in-flight work items and the only holder of pwq refs is the workqueue itself. This worked fine as a workqueue used to hold only one reference to its pwqs; however, since 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues"), a workqueue may hold multiple references to its default pwq triggering this sanity check spuriously. Fix it by not triggering the pwq->refcnt assertion on default pwqs. An example spurious WARN trigger follows. WARNING: at kernel/workqueue.c:4201 destroy_workqueue+0x6a/0x13e() Hardware name: 4286C12 Modules linked in: sdhci_pci sdhci mmc_core usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video Pid: 361, comm: umount Not tainted 3.9.0-rc5+ #29 Call Trace: [] warn_slowpath_common+0x7c/0x93 [] warn_slowpath_null+0x22/0x24 [] destroy_workqueue+0x6a/0x13e [] ext4_put_super+0x43/0x2c4 [] generic_shutdown_super+0x4b/0xb9 [] kill_block_super+0x22/0x60 [] deactivate_locked_super+0x2f/0x56 [] deactivate_super+0x2e/0x31 [] mntput_no_expire+0x103/0x108 [] sys_umount+0x2a2/0x2c4 [] sys_oldumount+0x1e/0x20 [] sysenter_do_call+0x12/0x38 tj: Rewrote description. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo Reported-by: Fengguang Wu