Hi, I got the following lockdep warning while booting a Dell XPS13. Is this a known issue? [ 13.836367] pciehp 0000:3b:04.0:pcie204: Slot #4 AttnBtn- PwrCtrl- MRL- AttnInd- PwrInd- HotPlug+ Surprise+ Interlock- NoCompl+ LLActRep+ [ 13.837149] ============================================ [ 13.837149] WARNING: possible recursive locking detected [ 13.837150] 5.0.0-00034-gcaae0ec7396f #54 Not tainted [ 13.837151] -------------------------------------------- [ 13.837152] irq/125-pciehp/165 is trying to acquire lock: [ 13.837153] 000000000f8f89cc (&ctrl->reset_lock){.+.+}, at: pciehp_check_presence+0x1b/0x72 [ 13.837159] but task is already holding lock: [ 13.837160] 000000001b052053 (&ctrl->reset_lock){.+.+}, at: pciehp_ist+0x10a/0x164 [ 13.837162] other info that might help us debug this: [ 13.837162] Possible unsafe locking scenario: [ 13.837163] CPU0 [ 13.837163] ---- [ 13.837164] lock(&ctrl->reset_lock); [ 13.837164] lock(&ctrl->reset_lock); [ 13.837165] *** DEADLOCK *** [ 13.837165] May be due to missing lock nesting notation [ 13.837166] 4 locks held by irq/125-pciehp/165: [ 13.837167] #0: 000000001b052053 (&ctrl->reset_lock){.+.+}, at: pciehp_ist+0x10a/0x164 [ 13.837169] #1: 0000000087e07843 (pci_rescan_remove_lock){+.+.}, at: pciehp_configure_device+0x1e/0xfd [ 13.837171] #2: 00000000e9b570d4 (&dev->mutex){....}, at: __device_attach+0x28/0x12d [ 13.837174] #3: 000000004add66ea (&dev->mutex){....}, at: __device_attach+0x28/0x12d [ 13.837176] stack backtrace: [ 13.837178] CPU: 7 PID: 165 Comm: irq/125-pciehp Not tainted 5.0.0-00034-gcaae0ec7396f #54 [ 13.837178] Hardware name: Dell Inc. XPS 13 9380/0KTW76, BIOS 1.2.1 02/14/2019 [ 13.837179] Call Trace: [ 13.837183] dump_stack+0x67/0x8e [ 13.837186] __lock_acquire+0x9b2/0xddc [ 13.837189] ? pci_hp_add+0x18a/0x1ee [ 13.837190] ? pci_hp_add+0x18a/0x1ee [ 13.837192] ? find_held_lock+0x2b/0x6e [ 13.837194] lock_acquire+0x147/0x172 [ 13.837196] ? pciehp_check_presence+0x1b/0x72 [ 13.837199] down_read+0x44/0x87 [ 13.837201] ? pciehp_check_presence+0x1b/0x72 [ 13.837203] pciehp_check_presence+0x1b/0x72 [ 13.837205] pciehp_probe+0x229/0x24d [ 13.837207] pcie_port_probe_service+0x38/0x4b [ 13.837209] really_probe+0x1a5/0x372 [ 13.837210] ? driver_allows_async_probing+0x2c/0x2c [ 13.837211] driver_probe_device+0xcf/0xff [ 13.837213] ? driver_allows_async_probing+0x2c/0x2c [ 13.837215] bus_for_each_drv+0x84/0xa8 [ 13.837217] __device_attach+0x9d/0x12d [ 13.837219] bus_probe_device+0x31/0x9e [ 13.837221] device_add+0x1c1/0x5bd [ 13.837223] ? __init_waitqueue_head+0x36/0x47 [ 13.837225] pcie_port_device_register+0x3b9/0x41e [ 13.837228] ? irq_thread_check_affinity+0x7b/0x7b [ 13.837230] pcie_portdrv_probe+0x37/0xa4 [ 13.837232] pci_device_probe+0xbe/0x130 [ 13.837234] really_probe+0x1a5/0x372 [ 13.837236] ? driver_allows_async_probing+0x2c/0x2c [ 13.837237] ? irq_thread+0x82/0x193 [ 13.837238] driver_probe_device+0xcf/0xff [ 13.837239] ? driver_allows_async_probing+0x2c/0x2c [ 13.837241] bus_for_each_drv+0x84/0xa8 [ 13.837242] __device_attach+0x9d/0x12d [ 13.837245] pci_bus_add_device+0x4a/0x83 [ 13.837247] pci_bus_add_devices+0x2c/0x5d [ 13.837248] pci_bus_add_devices+0x53/0x5d [ 13.837250] pciehp_configure_device+0xef/0xfd [ 13.837253] pciehp_handle_presence_or_link_change+0x28d/0x37b [ 13.837254] pciehhp_ist+0x12c/0x164 [ 13.837256] ? irq_finalize_oneshot+0x9e/0x9e [ 13.837257] irq_thread_fn+0x1e/0x41 [ 13.837259] irq_thread+0x138/0x193 [ 13.837261] ? wake_threads_waitq+0x27/0x27 [ 13.837263] ? irq_thread_check_affinity+0x7b/0x7b [ 13.837265] kthread+0xf7/0xfc [ 13.837266] ? kthread_cancel_delayed_work_sync+0xf/0xf [ 13.837269] ret_from_fork+0x3a/0x50 [ 13.837321] ------------[ cut here ]------------ It's followed by another warning which might be an unrelated issue; least, the stack trace looks unrelated. I've attached a compressed copy of the full dmesg.out in case it's helpful. Thanks!! - Ted [ 13.837321] downgrading a read lock [ 13.837327] WARNING: CPU: 2 PID: 741 at kernel/locking/lockdep.c:3553 lock_downgrade+0xe7/0x17f [ 13.837328] Modules linked in: nls_iso8859_1 nls_cp437 vfat fat snd_hda_codec_realtek snd_hda_codec_generic dell_laptop ledtrig_audio dell_wmi dell_smbios ath10k_pci joydev hid_multitouch(+) dcdbas intel_wmi_thunderbolt dell_wmi_descriptor intel_rapl x86_pkg_temp_thermal ath10k_core intel_powerclamp coretemp ath serio_raw kvm_intel snd_soc_skl btusb mac80211 snd_soc_core btrtl snd_soc_acpi_intel_match kvm btbcm snd_soc_acpi snd_soc_skl_ipc btintel snd_soc_sst_ipc irqbypass snd_soc_sst_dsp bluetooth snd_hda_ext_core uvcvideo cfg80211 videobuf2_vmalloc ecdh_generic videobuf2_memops snd_hda_intel i915 videobuf2_v4l2 videobuf2_common pcspkr snd_hda_codec snd_hwdep drm_kms_helper snd_hda_core idma64 drm mei_me processor_thermal_device intel_gtt intel_soc_dts_iosf fb_sys_fops mei syscopyarea sysfillrect intel_pch_thermal sysimgblt ucsi_acpi typec_ucsi int3403_thermal intel_hid int3400_thermal int340x_thermal_zone acpi_thermal_rel sparse_keymap acpi_pad pcc_cpufreq nfsd auth_rpcgss nfs_acl lockd [ 13.837356] grace parport_pc ppdev lp sunrpc parport ip_tables x_tables autofs4 btrfs zstd_decompress zstd_compress dm_thin_pool dm_persistent_data dm_bio_prison algif_skcipher af_alg raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear hid_generic i2c_designware_platform i2c_designware_core crct10dif_pclmul crc32_pclmul rtsx_pci_sdmmc ghash_clmulni_intel xhci_pci i2c_i801 thunderbolt intel_lpss_pci rtsx_pci intel_lpss xhci_hcd mfd_core i2c_hid hid [ 13.837374] CPU: 2 PID: 741 Comm: run-parts Not tainted 5.0.0-00034-gcaae0ec7396f #54 [ 13.837374] Hardware name: Dell Inc. XPS 13 9380/0KTW76, BIOS 1.2.1 02/14/2019 [ 13.837375] RIP: 0010:lock_downgrade+0xe7/0x17f [ 13.837376] Code: 00 00 00 8b 44 24 04 89 83 80 08 00 00 48 8b 45 00 48 89 83 78 08 00 00 f6 45 32 03 74 0e 48 c7 c7 eb 6e e7 ab e8 34 81 fb ff <0f> 0b 8a 45 32 4c 89 6d 08 44 89 e6 48 89 df 83 e0 fc 83 c8 01 88 [ 13.837377] RSP: 0018:ffff9dcbcf027e28 EFLAGS: 00010082 [ 13.837378] RAX: 0000000000000000 RBX: ffff9dcbcef3a9c0 RCX: 0000000000000000 [ 13.837379] RDX: ffff9dcbcef3a9c0 RSI: 0000000000000001 RDI: ffffffffab10ec18 [ 13.837379] RBP: ffff9dcbcef3b248 R08: 0000000000000017 R09: 00000000001e1e80 [ 13.837380] R10: ffff9dcbcef3a9c0 R11: 0000000a2851b6dd R12: 0000000000000001 [ 13.837380] R13: ffffffffab205904 R14: 0000000000000246 R15: ffff9dcbcef49b28 [ 13.837381] FS: 00007f6b961d7580(0000) GS:ffff9dcbdda00000(0000) knlGS:0000000000000000 [ 13.837382] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 13.837383] CR2: 000055a3940d7000 CR3: 0000000494962005 CR4: 00000000003606e0 [ 13.837383] Call Trace: [ 13.837387] downgrade_write+0x17/0x80 [ 13.837392] __do_munmap+0x26f/0x2fe [ 13.837394] __vm_munmap+0x74/0xbf [ 13.837396] __x64_sys_munmap+0x27/0x2c [ 13.837398] do_syscall_64+0x5e/0x6c [ 13.837400] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 13.837401] RIP: 0033:0x7f6b96214717 [ 13.837402] Code: ff ff ff f7 d8 89 05 48 ea 00 00 48 c7 c0 ff ff ff ff eb 8a 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0b 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8d 0d 19 ea 00 00 f7 d8 89 01 48 83 [ 13.837403] RSP: 002b:00007fffbd93f668 EFLAGS: 00000202 ORIG_RAX: 000000000000000b [ 13.837403] RAX: ffffffffffffffda RBX: 0000000a2851756f RCX: 00007f6b96214717 [ 13.837406] RDX: 0000000a2851a714 RSI: 0000000000021557 RDI: 00007f6b961d8000 [ 13.837406] RBP: 00007fffbd93f860 R08: 00007f6b9601a1f0 R09: 0000000000000007 [ 13.837407] R10: 00007f6b962229f0 R11: 0000000000000202 R12: 0000000000000000 [ 13.837407] R13: 00007f6b96223190 R14: 00007f6b961d7580 R15: 00007f6b96223190 [ 13.837409] irq event stamp: 719 [ 13.837413] hardirqs last enabled at (719): [] do_user_addr_fault+0xf3/0x396 [ 13.837414] hardirqs last disabled at (718): [] trace_hardirqs_off_thunk+0x1a/0x1c [ 13.837416] softirqs last enabled at (0): [] copy_process.part.43+0x452/0x1af8 [ 13.837421] softirqs last disabled at (0): [<0000000000000000>] (null) [ 13.837422] ---[ end trace 0c20cc7bb894cd38 ]---