Kernel panic in kernfs_kill_sb() while dereferencing super_block->s_root

Issue

• System crashed with following panic message in kernfs_kill_sb() routine

[2269474.782073] SLUB: Unable to allocate memory on node -1 (gfp=0xd0)
....
[2269474.782278] BUG: unable to handle kernel NULL pointer dereference at 0000000000000078
[2269474.784244] IP: [<ffffffffbd4c7cd3>] kernfs_kill_sb+0x23/0x70
...
[2269474.835665] Call Trace:
[2269474.837387]  [<ffffffffbd4cc6bf>] sysfs_kill_sb+0x1f/0x40
[2269474.839123]  [<ffffffffbd4442fe>] deactivate_locked_super+0x4e/0x70
[2269474.840801]  [<ffffffffbd4c7c51>] kernfs_mount_ns+0x1d1/0x230
[2269474.842450]  [<ffffffffbd4cc74a>] sysfs_mount+0x6a/0xd0
[2269474.844053]  [<ffffffffbd445bde>] mount_fs+0x3e/0x1b0
[2269474.845638]  [<ffffffffbd3daff5>] ? __alloc_percpu+0x15/0x20
[2269474.847183]  [<ffffffffbd463777>] vfs_kern_mount+0x67/0x110
[2269474.848696]  [<ffffffffbd465d9f>] do_mount+0x1ef/0xce0
[2269474.850155]  [<ffffffffbd43e03a>] ? __check_object_size+0x1ca/0x250
[2269474.851588]  [<ffffffffbd3d5eff>] ? memdup_user+0x4f/0x80
[2269474.852976]  [<ffffffffbd466bd3>] SyS_mount+0x83/0xd0
[2269474.854344]  [<ffffffffbd974ddb>] system_call_fastpath+0x22/0x27
[2269474.855664] Code: 0d 00 eb 9d 0f 1f 40 00 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 53 48 8b 47 60 48 89 fb 4c 8b a7 50 03 00 00 48 c7 c7 40 4a eb bd <4c> 8b 68 78 e8 24 e1 49 00 49 8d 7c 24 18 e8 aa cd 0c 00 48 c7 
[2269474.858446] RIP  [<ffffffffbd4c7cd3>] kernfs_kill_sb+0x23/0x70
[2269474.859784]  RSP <ffff8e7f3d3b3d30>
[2269474.861112] CR2: 0000000000000078