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authorTejun Heo <tj@kernel.org>2016-01-29 05:59:46 -0500
committerTejun Heo <tj@kernel.org>2016-01-29 13:31:10 -0500
commit23d11a58a9a60dcb52c8fc6494efce908b24c295 (patch)
tree353a68da22f03b60dca88cd782d2a75e62831248
parent92e963f50fc74041b5e9e744c330dca48e04f08d (diff)
workqueue: skip flush dependency checks for legacy workqueues
fca839c00a12 ("workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue") implemented flush dependency warning which triggers if a PF_MEMALLOC task or WQ_MEM_RECLAIM workqueue tries to flush a !WQ_MEM_RECLAIM workquee. This assumes that workqueues marked with WQ_MEM_RECLAIM sit in memory reclaim path and making it depend on something which may need more memory to make forward progress can lead to deadlocks. Unfortunately, workqueues created with the legacy create*_workqueue() interface always have WQ_MEM_RECLAIM regardless of whether they are depended upon memory reclaim or not. These spurious WQ_MEM_RECLAIM markings cause spurious triggering of the flush dependency checks. WARNING: CPU: 0 PID: 6 at kernel/workqueue.c:2361 check_flush_dependency+0x138/0x144() workqueue: WQ_MEM_RECLAIM deferwq:deferred_probe_work_func is flushing !WQ_MEM_RECLAIM events:lru_add_drain_per_cpu ... Workqueue: deferwq deferred_probe_work_func [<c0017acc>] (unwind_backtrace) from [<c0013134>] (show_stack+0x10/0x14) [<c0013134>] (show_stack) from [<c0245f18>] (dump_stack+0x94/0xd4) [<c0245f18>] (dump_stack) from [<c0026f9c>] (warn_slowpath_common+0x80/0xb0) [<c0026f9c>] (warn_slowpath_common) from [<c0026ffc>] (warn_slowpath_fmt+0x30/0x40) [<c0026ffc>] (warn_slowpath_fmt) from [<c00390b8>] (check_flush_dependency+0x138/0x144) [<c00390b8>] (check_flush_dependency) from [<c0039ca0>] (flush_work+0x50/0x15c) [<c0039ca0>] (flush_work) from [<c00c51b0>] (lru_add_drain_all+0x130/0x180) [<c00c51b0>] (lru_add_drain_all) from [<c00f728c>] (migrate_prep+0x8/0x10) [<c00f728c>] (migrate_prep) from [<c00bfbc4>] (alloc_contig_range+0xd8/0x338) [<c00bfbc4>] (alloc_contig_range) from [<c00f8f18>] (cma_alloc+0xe0/0x1ac) [<c00f8f18>] (cma_alloc) from [<c001cac4>] (__alloc_from_contiguous+0x38/0xd8) [<c001cac4>] (__alloc_from_contiguous) from [<c001ceb4>] (__dma_alloc+0x240/0x278) [<c001ceb4>] (__dma_alloc) from [<c001cf78>] (arm_dma_alloc+0x54/0x5c) [<c001cf78>] (arm_dma_alloc) from [<c0355ea4>] (dmam_alloc_coherent+0xc0/0xec) [<c0355ea4>] (dmam_alloc_coherent) from [<c039cc4c>] (ahci_port_start+0x150/0x1dc) [<c039cc4c>] (ahci_port_start) from [<c0384734>] (ata_host_start.part.3+0xc8/0x1c8) [<c0384734>] (ata_host_start.part.3) from [<c03898dc>] (ata_host_activate+0x50/0x148) [<c03898dc>] (ata_host_activate) from [<c039d558>] (ahci_host_activate+0x44/0x114) [<c039d558>] (ahci_host_activate) from [<c039f05c>] (ahci_platform_init_host+0x1d8/0x3c8) [<c039f05c>] (ahci_platform_init_host) from [<c039e6bc>] (tegra_ahci_probe+0x448/0x4e8) [<c039e6bc>] (tegra_ahci_probe) from [<c0347058>] (platform_drv_probe+0x50/0xac) [<c0347058>] (platform_drv_probe) from [<c03458cc>] (driver_probe_device+0x214/0x2c0) [<c03458cc>] (driver_probe_device) from [<c0343cc0>] (bus_for_each_drv+0x60/0x94) [<c0343cc0>] (bus_for_each_drv) from [<c03455d8>] (__device_attach+0xb0/0x114) [<c03455d8>] (__device_attach) from [<c0344ab8>] (bus_probe_device+0x84/0x8c) [<c0344ab8>] (bus_probe_device) from [<c0344f48>] (deferred_probe_work_func+0x68/0x98) [<c0344f48>] (deferred_probe_work_func) from [<c003b738>] (process_one_work+0x120/0x3f8) [<c003b738>] (process_one_work) from [<c003ba48>] (worker_thread+0x38/0x55c) [<c003ba48>] (worker_thread) from [<c0040f14>] (kthread+0xdc/0xf4) [<c0040f14>] (kthread) from [<c000f778>] (ret_from_fork+0x14/0x3c) Fix it by marking workqueues created via create*_workqueue() with __WQ_LEGACY and disabling flush dependency checks on them. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Thierry Reding <thierry.reding@gmail.com> Link: http://lkml.kernel.org/g/20160126173843.GA11115@ulmo.nvidia.com Fixes: fca839c00a12 ("workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue")
-rw-r--r--include/linux/workqueue.h9
-rw-r--r--kernel/workqueue.c3
2 files changed, 7 insertions, 5 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 0e32bc71245e..ca73c503b92a 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -311,6 +311,7 @@ enum {
311 311
312 __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */ 312 __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */
313 __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */ 313 __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */
314 __WQ_LEGACY = 1 << 18, /* internal: create*_workqueue() */
314 315
315 WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */ 316 WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */
316 WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */ 317 WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
@@ -411,12 +412,12 @@ __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
411 alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args) 412 alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args)
412 413
413#define create_workqueue(name) \ 414#define create_workqueue(name) \
414 alloc_workqueue("%s", WQ_MEM_RECLAIM, 1, (name)) 415 alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, 1, (name))
415#define create_freezable_workqueue(name) \ 416#define create_freezable_workqueue(name) \
416 alloc_workqueue("%s", WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, \ 417 alloc_workqueue("%s", __WQ_LEGACY | WQ_FREEZABLE | WQ_UNBOUND | \
417 1, (name)) 418 WQ_MEM_RECLAIM, 1, (name))
418#define create_singlethread_workqueue(name) \ 419#define create_singlethread_workqueue(name) \
419 alloc_ordered_workqueue("%s", WQ_MEM_RECLAIM, name) 420 alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
420 421
421extern void destroy_workqueue(struct workqueue_struct *wq); 422extern void destroy_workqueue(struct workqueue_struct *wq);
422 423
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 61a0264e28f9..dc7faad63646 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2355,7 +2355,8 @@ static void check_flush_dependency(struct workqueue_struct *target_wq,
2355 WARN_ONCE(current->flags & PF_MEMALLOC, 2355 WARN_ONCE(current->flags & PF_MEMALLOC,
2356 "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%pf", 2356 "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%pf",
2357 current->pid, current->comm, target_wq->name, target_func); 2357 current->pid, current->comm, target_wq->name, target_func);
2358 WARN_ONCE(worker && (worker->current_pwq->wq->flags & WQ_MEM_RECLAIM), 2358 WARN_ONCE(worker && ((worker->current_pwq->wq->flags &
2359 (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM),
2359 "workqueue: WQ_MEM_RECLAIM %s:%pf is flushing !WQ_MEM_RECLAIM %s:%pf", 2360 "workqueue: WQ_MEM_RECLAIM %s:%pf is flushing !WQ_MEM_RECLAIM %s:%pf",
2360 worker->current_pwq->wq->name, worker->current_func, 2361 worker->current_pwq->wq->name, worker->current_func,
2361 target_wq->name, target_func); 2362 target_wq->name, target_func);