Hi Niklas, jFYI/FWIW, checking the functionality of rcar-vin using the procedure/commands described in https://elinux.org/R-Car/Tests:rcar-vin on the recent Linux commit ea2cec24c8d429ee6f99040e4eb6c7ad627fe777, I consistently reproduce below lockdep splat [2] (full log and .config at https://gist.github.com/erosca/67a46451b3cb342fa59b558022278fff). Since the locking primitives of rvin_group_link_notify (popping up in the log) haven't suffered changes since v4.18-rc1 commit [1], I conclude this thread [0] might be an appropriate place for reporting the issue. Best regards, Eugeniu. [0] https://patchwork.kernel.org/patch/10341183/ [v14,29/33] rcar-vin: add link notify for Gen3 [1] c0cc5aef31704c ("media: rcar-vin: add link notify for Gen3") [2] media-ctl -l "'rcar_csi2 feaa0000.csi2':1 -> 'VIN0 output':0 [1]" ====================================================== WARNING: possible circular locking dependency detected 5.1.0-rc3+ #27 Tainted: G W ------------------------------------------------------ media-ctl/2407 is trying to acquire lock: 00000000be992082 (&group->lock){+.+.}, at: rvin_group_link_notify+0xc4/0x4f4 but task is already holding lock: 0000000064693a2a (&mdev->graph_mutex){+.+.}, at: media_device_ioctl+0x1f8/0x2b8 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&mdev->graph_mutex){+.+.}: lock_acquire+0x144/0x39c __mutex_lock+0xe8/0xb54 mutex_lock_nested+0x3c/0x4c media_device_register_entity+0x15c/0x308 v4l2_device_register_subdev+0x1c8/0x288 v4l2_async_match_notify+0x3c/0x200 v4l2_async_notifier_try_all_subdevs+0xb8/0xc0 __v4l2_async_notifier_register+0xac/0x214 v4l2_async_notifier_register+0x68/0x80 rcar_vin_probe+0x8d8/0xa0c platform_drv_probe+0x70/0xe4 really_probe+0x2d8/0x3d8 driver_probe_device+0x154/0x164 device_driver_attach+0x98/0xa0 __driver_attach+0xf0/0xf4 bus_for_each_dev+0x114/0x13c driver_attach+0x38/0x44 bus_add_driver+0x234/0x288 driver_register+0x148/0x190 __platform_driver_register+0x84/0x90 rcar_vin_driver_init+0x20/0x28 do_one_initcall+0x124/0x68c kernel_init_freeable+0xa5c/0xa60 kernel_init+0x18/0x134 ret_from_fork+0x10/0x18 -> #1 (list_lock){+.+.}: lock_acquire+0x144/0x39c __mutex_lock+0xe8/0xb54 mutex_lock_nested+0x3c/0x4c v4l2_async_notifier_add_subdev+0x3c/0xdc __v4l2_async_notifier_parse_fwnode_ep+0x240/0x2b8 v4l2_async_notifier_parse_fwnode_endpoints_by_port+0x4c/0x60 rcar_vin_probe+0x858/0xa0c platform_drv_probe+0x70/0xe4 really_probe+0x2d8/0x3d8 driver_probe_device+0x154/0x164 device_driver_attach+0x98/0xa0 __driver_attach+0xf0/0xf4 bus_for_each_dev+0x114/0x13c driver_attach+0x38/0x44 bus_add_driver+0x234/0x288 driver_register+0x148/0x190 __platform_driver_register+0x84/0x90 rcar_vin_driver_init+0x20/0x28 do_one_initcall+0x124/0x68c kernel_init_freeable+0xa5c/0xa60 kernel_init+0x18/0x134 ret_from_fork+0x10/0x18 -> #0 (&group->lock){+.+.}: __lock_acquire+0x1c7c/0x1dd0 lock_acquire+0x144/0x39c __mutex_lock+0xe8/0xb54 mutex_lock_nested+0x3c/0x4c rvin_group_link_notify+0xc4/0x4f4 __media_entity_setup_link+0x238/0x2f0 media_device_setup_link+0x114/0x11c media_device_ioctl+0x21c/0x2b8 __media_ioctl+0x78/0x84 media_ioctl+0x58/0x68 vfs_ioctl+0x68/0x78 do_vfs_ioctl+0x134/0xbfc ksys_ioctl+0x68/0x98 __arm64_sys_ioctl+0x4c/0x60 el0_svc_common+0xd0/0x16c el0_svc_handler+0x94/0xa0 el0_svc+0x8/0xc other info that might help us debug this: Chain exists of: &group->lock --> list_lock --> &mdev->graph_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mdev->graph_mutex); lock(list_lock); lock(&mdev->graph_mutex); lock(&group->lock); *** DEADLOCK *** 1 lock held by media-ctl/2407: #0: 0000000064693a2a (&mdev->graph_mutex){+.+.}, at: media_device_ioctl+0x1f8/0x2b8 stack backtrace: CPU: 0 PID: 2407 Comm: media-ctl Tainted: G W 5.1.0-rc3+ #27 Hardware name: Renesas Salvator-X board based on r8a7795 ES2.0+ (DT) Call trace: dump_backtrace+0x0/0x1c0 show_stack+0x24/0x30 dump_stack+0xcc/0x128 print_circular_bug.isra.16+0x22c/0x364 check_prev_add.constprop.25+0x35c/0x1098 __lock_acquire+0x1c7c/0x1dd0 lock_acquire+0x144/0x39c __mutex_lock+0xe8/0xb54 mutex_lock_nested+0x3c/0x4c rvin_group_link_notify+0xc4/0x4f4 __media_entity_setup_link+0x238/0x2f0 media_device_setup_link+0x114/0x11c media_device_ioctl+0x21c/0x2b8 __media_ioctl+0x78/0x84 media_ioctl+0x58/0x68 vfs_ioctl+0x68/0x78 do_vfs_ioctl+0x134/0xbfc ksys_ioctl+0x68/0x98 __arm64_sys_ioctl+0x4c/0x60 el0_svc_common+0xd0/0x16c el0_svc_handler+0x94/0xa0 el0_svc+0x8/0xc
