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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 /kernel/workqueue.c
parent92e963f50fc74041b5e9e744c330dca48e04f08d (diff)
downloadlinux-sh-23d11a58a9a60dcb52c8fc6494efce908b24c295.tar.gz
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")
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r--kernel/workqueue.c3
1 files changed, 2 insertions, 1 deletions
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,
WARN_ONCE(current->flags & PF_MEMALLOC,
"workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%pf",
current->pid, current->comm, target_wq->name, target_func);
- WARN_ONCE(worker && (worker->current_pwq->wq->flags & WQ_MEM_RECLAIM),
+ WARN_ONCE(worker && ((worker->current_pwq->wq->flags &
+ (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM),
"workqueue: WQ_MEM_RECLAIM %s:%pf is flushing !WQ_MEM_RECLAIM %s:%pf",
worker->current_pwq->wq->name, worker->current_func,
target_wq->name, target_func);