Additional info:
reporter:       libreport-2.9.5
WARNING: CPU: 2 PID: 529 at kernel/locking/lockdep.c:3647 lock_downgrade+0x13b/0x1c0
Modules linked in: ccm tun ipt_MASQUERADE iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype xt_conntrack nf_nat nf_conntrack br_netfilter devlink ip6table_filter ip6_tables ip_set nfnetlink ebtable_nat ebtable_broute bridge stp llc ebtable_filter ebtables sunrpc vfat fat snd_hda_codec_hdmi arc4 intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp iwlmvm pn544_mei mei_phy pn544 hci nfc kvm_intel iTCO_wdt wmi_bmof mac80211 gpio_ich iTCO_vendor_support i915 kvm iwlwifi uvcvideo irqbypass crct10dif_pclmul videobuf2_vmalloc crc32_pclmul videobuf2_memops videobuf2_v4l2 ghash_clmulni_intel videobuf2_common snd_hda_codec_realtek intel_cstate intel_uncore snd_hda_codec_generic videodev intel_rapl_perf snd_hda_intel snd_hda_codec i2c_algo_bit joydev cfg80211 media drm_kms_helper
 toshiba_acpi snd_hda_core rtsx_pci_ms sparse_keymap toshiba_bluetooth snd_hwdep memstick mmc_block industrialio snd_seq rfkill snd_seq_device snd_pcm tpm_infineon drm mei_me snd_timer mei wmi snd video ie31200_edac soundcore lpc_ich btrfs libcrc32c xor zstd_decompress zstd_compress rtsx_pci_sdmmc xxhash mmc_core raid6_pq crc32c_intel e1000e serio_raw rtsx_pci
CPU: 2 PID: 529 Comm: systemd-journal Not tainted 4.18.0-0.rc4.git1.1.fc29.x86_64 #1
Hardware name: TOSHIBA dynabook R73/PB/dynabook R73/PB, BIOS Version 4.80   06/23/2015
RIP: 0010:lock_downgrade+0x13b/0x1c0
Code: 18 5b 5d 41 5c 41 5d 41 5e c3 4c 89 e2 4c 89 f6 48 89 df e8 17 cb ff ff eb b2 48 c7 c7 27 38 2f bc 48 89 04 24 e8 79 53 f9 ff <0f> 0b 8b 54 24 0c 48 8b 04 24 e9 5c ff ff ff e8 51 c9 3e 00 85 c0 
RSP: 0018:ffffbe39826ffd70 EFLAGS: 00010082
RAX: 0000000000000000 RBX: ffff953c552f8000 RCX: 0000000000000006
RDX: 0000000000000007 RSI: 0000000000000001 RDI: ffff953c5e1d6cc0
RBP: 0000000000000246 R08: 0000000000000000 R09: 0000000000000001
R10: ffff953c552f8000 R11: 0000000000000001 R12: ffffffffc041969e
R13: 0000000000000001 R14: ffff953c4f99b518 R15: ffffbe39826ffe18
FS:  00007f3adfe9f940(0000) GS:ffff953c5e000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005566e34db000 CR3: 000000041361a002 CR4: 00000000001606e0
Call Trace:
 downgrade_write+0x17/0x90
 btrfs_real_readdir+0x43e/0x4a0 [btrfs]
 iterate_dir+0x148/0x190
 ksys_getdents64+0xae/0x140
 ? iterate_dir+0x190/0x190
 __x64_sys_getdents64+0x16/0x20
 do_syscall_64+0x60/0x1f0
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f3adef264db
Code: 00 00 48 83 c4 08 5b 5d c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 8b 47 20 c3 0f 1f 80 00 00 00 00 f3 0f 1e fa b8 d9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 8b 15 79 89 2f 00 f7 d8 
RSP: 002b:00007ffe4916e848 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00005566e34da2d0 RCX: 00007f3adef264db
RDX: 0000000000008000 RSI: 00005566e34da300 RDI: 0000000000000033
RBP: 00005566e34da300 R08: 0000000000000003 R09: 0000000000000078
R10: 00005566e34a7010 R11: 0000000000000246 R12: fffffffffffffdd8
R13: 0000000000000000 R14: 00007ffe4916e9e8 R15: 00005566e34da2d0
irq event stamp: 93114
hardirqs last  enabled at (93113): [<ffffffffbba3e719>] _raw_spin_unlock_irq+0x29/0x40
hardirqs last disabled at (93114): [<ffffffffbba362e4>] __schedule+0xc4/0xb00
softirqs last  enabled at (91472): [<ffffffffbbe0038c>] __do_softirq+0x38c/0x4f7
softirqs last disabled at (91371): [<ffffffffbb0c1911>] irq_exit+0x101/0x110