From: Loic Poulain loic.poulain@linaro.org
commit 0fccbf0a3b690b162f53b13ed8bc442ea33437dc upstream.
A recent change created a dedicated workqueue for the state-change work with WQ_HIGHPRI (no strong reason for that) and WQ_MEM_RECLAIM flags, but the state-change work (mhi_pm_st_worker) does not guarantee forward progress under memory pressure, and will even wait on various memory allocations when e.g. creating devices, loading firmware, etc... The work is then not part of a memory reclaim path...
Moreover, this causes a warning in check_flush_dependency() since we end up in code that flushes a non-reclaim workqueue:
[ 40.969601] workqueue: WQ_MEM_RECLAIM mhi_hiprio_wq:mhi_pm_st_worker [mhi] is flushing !WQ_MEM_RECLAIM events_highpri:flush_backlog [ 40.969612] WARNING: CPU: 4 PID: 158 at kernel/workqueue.c:2607 check_flush_dependency+0x11c/0x140 [ 40.969733] Call Trace: [ 40.969740] __flush_work+0x97/0x1d0 [ 40.969745] ? wake_up_process+0x15/0x20 [ 40.969749] ? insert_work+0x70/0x80 [ 40.969750] ? __queue_work+0x14a/0x3e0 [ 40.969753] flush_work+0x10/0x20 [ 40.969756] rollback_registered_many+0x1c9/0x510 [ 40.969759] unregister_netdevice_queue+0x94/0x120 [ 40.969761] unregister_netdev+0x1d/0x30 [ 40.969765] mhi_net_remove+0x1a/0x40 [mhi_net] [ 40.969770] mhi_driver_remove+0x124/0x250 [mhi] [ 40.969776] device_release_driver_internal+0xf0/0x1d0 [ 40.969778] device_release_driver+0x12/0x20 [ 40.969782] bus_remove_device+0xe1/0x150 [ 40.969786] device_del+0x17b/0x3e0 [ 40.969791] mhi_destroy_device+0x9a/0x100 [mhi] [ 40.969796] ? mhi_unmap_single_use_bb+0x50/0x50 [mhi] [ 40.969799] device_for_each_child+0x5e/0xa0 [ 40.969804] mhi_pm_st_worker+0x921/0xf50 [mhi]
Fixes: 8f7039787687 ("bus: mhi: core: Move to using high priority workqueue") Signed-off-by: Loic Poulain loic.poulain@linaro.org Reviewed-by: Bhaumik Bhatt bbhatt@codeaurora.org Reviewed-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org Link: https://lore.kernel.org/r/1614161930-8513-1-git-send-email-loic.poulain@lina... Signed-off-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/bus/mhi/core/init.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/bus/mhi/core/init.c +++ b/drivers/bus/mhi/core/init.c @@ -896,8 +896,7 @@ int mhi_register_controller(struct mhi_c INIT_WORK(&mhi_cntrl->st_worker, mhi_pm_st_worker); init_waitqueue_head(&mhi_cntrl->state_event);
- mhi_cntrl->hiprio_wq = alloc_ordered_workqueue - ("mhi_hiprio_wq", WQ_MEM_RECLAIM | WQ_HIGHPRI); + mhi_cntrl->hiprio_wq = alloc_ordered_workqueue("mhi_hiprio_wq", WQ_HIGHPRI); if (!mhi_cntrl->hiprio_wq) { dev_err(mhi_cntrl->cntrl_dev, "Failed to allocate workqueue\n"); ret = -ENOMEM;