Crash in dm-delay device accessing NULL pointer

Issue

• Crash in dm-delay device accessing NULL pointer

[ 7025.434313] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
[ 7025.434338] PGD 0 P4D 0 
[ 7025.434348] Oops: 0002 [#1] SMP NOPTI
[ 7025.434359] CPU: 3 PID: 8555 Comm: dmsetup Kdump: loaded Not tainted 4.18.0-147.5.1.el8_1.x86_64 #1
[ 7025.434380] Hardware name: VMware, Inc. VMware7,1/440BX Desktop Reference Platform, BIOS VMW71.00V.13989454.B64.1906190538 06/19/2019
[ 7025.434414] RIP: 0010:mutex_lock+0x19/0x30
[ 7025.434426] Code: 00 0f 1f 44 00 00 be 02 00 00 00 e9 51 fb ff ff 90 0f 1f 44 00 00 53 48 89 fb e8 62 dc ff ff 31 c0 65 48 8b 14 25 80 5c 01 00 <f0> 48 0f b1 13 74 06 48 89 df 5b eb ca 5b c3 0f 1f 84 00 00 00 00
[ 7025.434467] RSP: 0018:ffffaa1b9ba47b98 EFLAGS: 00010246
[ 7025.434481] RAX: 0000000000000000 RBX: 0000000000000020 RCX: 0000000000000000
[ 7025.434497] RDX: ffff97dcb9b18000 RSI: 0000000000000000 RDI: 0000000000000020
[ 7025.434515] RBP: 0000000000000020 R08: 0000000000028080 R09: ffffffffc0374b81
[ 7025.434531] R10: fffffd004df7fdc0 R11: 0000000000000000 R12: 0000000000000000
[ 7025.434547] R13: 0000000000000020 R14: 00000000fffffff0 R15: 0000000000000000
[ 7025.434564] FS:  00007f6d90e5d880(0000) GS:ffff97e6c58c0000(0000) knlGS:0000000000000000
[ 7025.434582] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 7025.434596] CR2: 0000000000000020 CR3: 00000033b1fb8005 CR4: 00000000007606e0
[ 7025.434639] PKRU: 55555554
[ 7025.434648] Call Trace:
[ 7025.434665]  drain_workqueue+0x1a/0x120
[ 7025.434678]  destroy_workqueue+0x15/0x1e0
[ 7025.434690]  delay_dtr+0x17/0x60 [dm_delay]
[ 7025.434701]  delay_ctr+0x19e/0x214 [dm_delay]
[ 7025.434718]  dm_table_add_target+0x17d/0x360 [dm_mod]
[ 7025.434733]  table_load+0x122/0x2e0 [dm_mod]
[ 7025.434747]  ? dev_status+0x40/0x40 [dm_mod]
[ 7025.434759]  ctl_ioctl+0x1af/0x3f0 [dm_mod]
[ 7025.434773]  ? selinux_file_ioctl+0xb0/0x200
[ 7025.434786]  dm_ctl_ioctl+0xa/0x10 [dm_mod]
[ 7025.434800]  do_vfs_ioctl+0xa4/0x630
[ 7025.434811]  ksys_ioctl+0x60/0x90
[ 7025.434820]  __x64_sys_ioctl+0x16/0x20
[ 7025.434832]  do_syscall_64+0x5b/0x1b0
[ 7025.434845]  entry_SYSCALL_64_after_hwframe+0x65/0xca
[ 7025.434859] RIP: 0033:0x7f6d90721b2b
[ 7025.434869] Code: 0f 1e fa 48 8b 05 5d a3 2c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 2d a3 2c 00 f7 d8 64 89 01 48
[ 7025.434912] RSP: 002b:00007ffc5acea6a8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
[ 7025.434930] RAX: ffffffffffffffda RBX: 00007f6d90a00070 RCX: 00007f6d90721b2b
[ 7025.434946] RDX: 0000563baf702ce0 RSI: 00000000c138fd09 RDI: 0000000000000003
[ 7025.434962] RBP: 00007f6d90a3b0c3 R08: 00007f6d90a3bc50 R09: 00007ffc5acea510
[ 7025.434979] R10: 00007f6d90a3b0c3 R11: 0000000000000202 R12: 0000563baf702ce0
[ 7025.434996] R13: 0000000000000000 R14: 0000563baf702d90 R15: 0000563baf7016b0
[ 7025.435513] Modules linked in: dm_delay nfsv3 nfs_acl rpcsec_gss_krb5 nfsv4 dns_resolver nfs lockd grace fscache vmw_vsock_vmci_transport vsock vfat fat vmw_balloon nfit libnvdimm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel intel_rapl_perf pcspkr joydev sg vmw_vmci i2c_piix4 auth_rpcgss binfmt_misc sunrpc xfs libcrc32c sr_mod cdrom ata_generic sd_mod vmwgfx drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ahci ttm crc32c_intel serio_raw libahci drm ata_piix vmxnet3 libata vmw_pvscsi dm_mirror dm_region_hash dm_log dm_mod
[ 7025.438061] CR2: 0000000000000020