Hello. I have kernel panic after clearing stats on kernel 5.4.12. Steps to reproduce: 1. Create new set: make-bcache -B /dev/nvme1n1 -C /dev/sda --wipe-bcache 2. Run in /sys/fs/bcache/<uuid>: echo 1 > clear_stats && cat stats_five_minute/cache_bypass_hits [14640.589843] BUG: kernel NULL pointer dereference, address: 0000000000000000 [14640.591006] #PF: supervisor read access in kernel mode [14640.592123] #PF: error_code(0x0000) - not-present page [14640.593217] PGD 68498e067 P4D 68498e067 PUD 5edb19067 PMD 0 [14640.594335] Oops: 0000 [#1] SMP NOPTI [14640.595425] CPU: 3 PID: 45788 Comm: file Kdump: loaded Not tainted 5.4.12-1.el7.x86_64 #1 [14640.596526] Hardware name: Dell Inc. PowerEdge R515/0Y9CHX, BIOS 2.4.1 05/04/2018 [14640.597636] RIP: 0010:sysfs_kf_seq_show+0xaa/0x1a0 [14640.598754] Code: 00 00 00 40 f6 c7 04 0f 85 b8 00 00 00 44 89 c9 31 c0 c1 e9 03 41 f6 c1 04 f3 48 ab 75 7d 41 f6 c1 02 75 65 41 83 e1 01 75 4e <49> 8b 04 24 48 85 c0 74 51 48 8b 0e 4c 89 c7 48 8b 71 60 e8 ee 3b [14640.601034] RSP: 0018:ffffc9000cfe7dc8 EFLAGS: 00010246 [14640.602172] RAX: 0000000000000000 RBX: ffff8888361e4300 RCX: 0000000000000000 [14640.603318] RDX: ffff888840643000 RSI: ffff88879c76cfc0 RDI: ffff888840644000 [14640.604474] RBP: ffffc9000cfe7dd8 R08: ffff8890166e01c0 R09: 0000000000000000 [14640.605607] R10: 0000000000001000 R11: 0000000000000000 R12: 0000000000000000 [14640.606724] R13: ffff88884cc72300 R14: ffff8888361e4300 R15: 0000000000000001 [14640.607849] FS: 00007fa3d82cf740(0000) GS:ffff88885fac0000(0000) knlGS:0000000000000000 [14640.608985] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [14640.610096] CR2: 0000000000000000 CR3: 00000005c6268000 CR4: 00000000000406e0 [14640.611213] Call Trace: [14640.612332] kernfs_seq_show+0x27/0x30 [14640.613434] seq_read+0x161/0x3f0 [14640.614514] kernfs_fop_read+0x11f/0x1b0 [14640.615591] __vfs_read+0x1b/0x40 [14640.616668] vfs_read+0x8e/0x140 [14640.617722] ksys_read+0x61/0xd0 [14640.618758] __x64_sys_read+0x1a/0x20 [14640.619774] do_syscall_64+0x60/0x1c0 [14640.620792] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [14640.621802] RIP: 0033:0x7fa3d79997e0 [14640.622799] Code: 0b 31 c0 48 83 c4 08 e9 be fe ff ff 48 8d 3d bf 85 09 00 e8 82 65 02 00 66 90 83 3d 9d 87 2d 00 00 75 10 b8 00 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 2e c7 01 00 48 89 04 24 [14640.624861] RSP: 002b:00007fffd20b5d18 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [14640.625895] RAX: ffffffffffffffda RBX: 00007fa3d8287010 RCX: 00007fa3d79997e0 [14640.626953] RDX: 0000000000040000 RSI: 00007fa3d8287010 RDI: 0000000000000003 [14640.627989] RBP: 0000000000000003 R08: ffffffffffffffff R09: 0000000000040041 [14640.629016] R10: 00007fffd20b59a0 R11: 0000000000000246 R12: 000000000145ff20 [14640.630032] R13: 00007fffd20b7710 R14: 0000000000000000 R15: 000000000000004e [14640.631039] Modules linked in: bcache crc64 mpt3sas raid_class scsi_transport_sas mptctl mptbase dell_rbu xt_nat veth xt_MASQUERADE nf_conntrack_netlink xt_addrtype overlay 8021q garp mrp bonding ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 ipt_REJECT nf_reject_ipv4 xt_conntrack ebtable_nat ebtable_broute ip6table_nat ip6table_mangle ip6table_security ip6table_raw iptable_nat nf_nat iptable_mangle iptable_security iptable_raw nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c rfkill ip_set nfnetlink ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter amd64_edac_mod edac_mce_amd kvm_amd ccp kvm irqbypass dcdbas crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel sr_mod crypto_simd cryptd cdrom joydev glue_helper input_leds pcspkr sg ipmi_si ipmi_devintf ipmi_msghandler acpi_power_meter sp5100_tco k10temp i2c_piix4 fam15h_power ip_tables ext4 mbcache jbd2 uas usb_storage sd_mod ata_generic pata_acpi mgag200 drm_kms_helper syscopyarea crc32c_intel sysfillrect sysimgblt [14640.631078] fb_sys_fops drm_vram_helper ttm serio_raw drm i2c_algo_bit ahci pata_atiixp libahci nvme ixgbe libata mdio bnx2 megaraid_sas ptp pps_core nvme_core dca [last unloaded: bcache] [14640.642359] CR2: 0000000000000000
