Hi, everyone, I apologise in advance if I've sent this to {too many, the wrong} people. For some time now, I've been getting sporadic (in about one out of five boots) DRM-related RCU complaints on an Ivy Bridge-based (Core i7-3720QM) Mac Mini. Call trace (on Linux 6.3-rc6) follows: [ 5.794026] rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-.... } 3 jiffies s: 309 root: 0x1/. [ 5.794044] rcu: blocking rcu_node structures (internal RCU debug): [ 5.794045] Sending NMI from CPU 1 to CPUs 0: [ 5.794049] NMI backtrace for cpu 0 [ 5.794051] CPU: 0 PID: 537 Comm: Xorg Not tainted 6.3.0-rc6-debug+ #57 [ 5.794053] Hardware name: Apple Inc. Macmini6,2/Mac-F65AE981FFA204ED, BIOS 429.0.0.0.0 03/18/2022 [ 5.794054] RIP: 0010:fwtable_read32+0x45/0x100 [ 5.794060] Code: 5e 00 49 89 c5 48 8b 45 08 8b b0 2c 1d 00 00 85 f6 0f 85 94 00 00 00 8d 83 00 00 fc ff 3d ff 5f 0d 00 77 28 48 03 5d 00 8b 1b <48> 8b 45 08 8b 88 2c 1d 00 00 85 c9 75 48 4c 89 ee 4c 89 e7 e8 82 [ 5.794061] RSP: 0018:ffff88810d17f968 EFLAGS: 00000082 [ 5.794063] RAX: 0000000000085010 RBX: 0000000000000200 RCX: ffff888101d80000 [ 5.794064] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff888101d81f28 [ 5.794064] RBP: ffff888101d81f08 R08: 0000000000000000 R09: 00000000000032ab [ 5.794065] R10: 0000000000000001 R11: 00000000000061b2 R12: ffff888101d81f28 [ 5.794066] R13: 0000000000000246 R14: ffff888102f693d0 R15: ffff88810d17faef [ 5.794067] FS: 00007f579a20da80(0000) GS:ffff888267200000(0000) knlGS:0000000000000000 [ 5.794068] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 5.794069] CR2: 000055fe9b660028 CR3: 0000000111e97004 CR4: 00000000001706f0 [ 5.794069] Call Trace: [ 5.794071] <TASK> [ 5.794073] get_reserved.isra.0+0x23/0x30 [ 5.794076] get_clock+0x25/0x70 [ 5.794078] sclhi+0x43/0x70 [ 5.794081] i2c_stop+0x2b/0x40 [ 5.794083] bit_xfer+0x22a/0x5d0 [ 5.794085] ? __pm_runtime_resume+0x40/0x50 [ 5.794088] ? __intel_display_power_get_domain.part.0+0x4d/0x60 [ 5.794092] gmbus_xfer+0x3c/0x90 [ 5.794094] __i2c_transfer+0x15b/0x4d0 [ 5.794096] i2c_transfer+0x3c/0xa0 [ 5.794098] drm_do_probe_ddc_edid+0xad/0x120 [ 5.794101] drm_get_edid+0x71/0x90 [ 5.794104] intel_crt_get_edid+0xf/0x80 [ 5.794106] intel_crt_detect_ddc+0x28/0xc0 [ 5.794107] intel_crt_detect+0x1f5/0xc40 [ 5.794108] ? pollwake+0x61/0x70 [ 5.794111] drm_helper_probe_detect+0x43/0xa0 [ 5.794115] drm_helper_probe_single_connector_modes+0x403/0x490 [ 5.794117] drm_mode_getconnector+0x32d/0x430 [ 5.794119] ? drm_connector_list_iter_next+0x7c/0xa0 [ 5.794120] ? drm_connector_property_set_ioctl+0x30/0x30 [ 5.794122] drm_ioctl_kernel+0x91/0x130 [ 5.794124] drm_ioctl+0x1d8/0x410 [ 5.794125] ? drm_connector_property_set_ioctl+0x30/0x30 [ 5.794127] __x64_sys_ioctl+0x3b9/0x8f0 [ 5.794129] ? handle_mm_fault+0xc1/0x170 [ 5.794131] ? exc_page_fault+0x18b/0x470 [ 5.794134] do_syscall_64+0x2b/0x50 [ 5.794136] entry_SYSCALL_64_after_hwframe+0x46/0xb0 [ 5.794139] RIP: 0033:0x7f579a1119ef [ 5.794141] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 18 48 8b 44 24 18 64 48 2b 04 25 28 00 00 [ 5.794142] RSP: 002b:00007ffc1dee7620 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 5.794143] RAX: ffffffffffffffda RBX: 000055fe9b660060 RCX: 00007f579a1119ef [ 5.794144] RDX: 00007ffc1dee76c0 RSI: 00000000c05064a7 RDI: 000000000000000f [ 5.794144] RBP: 00007ffc1dee76c0 R08: 0000000000000000 R09: 0000000000000000 [ 5.794145] R10: 00007f579a6bc1d8 R11: 0000000000000246 R12: 00000000c05064a7 [ 5.794146] R13: 000000000000000f R14: 00000000c05064a7 R15: 00007ffc1dee76c0 [ 5.794147] </TASK> Please let me know if you need any additional information (kconfig, etc.) in order to fix this. I will, of course, be happy to test any patch thrown my way. Kind regards, Rui