BUG when removing, fixed by reverting this patch. [ 346.548512] mmc1: card 0001 removed [ 346.552782] BUG: unable to handle kernel NULL pointer dereference at 0000000000000070 [ 346.561539] IP: kernfs_find_ns+0xe/0xc0 [ 346.565822] PGD 179dc5067 P4D 179dc5067 PUD 171106067 PMD 0 [ 346.572152] Oops: 0000 [#1] SMP [ 346.575657] Modules linked in: [ 346.579069] CPU: 0 PID: 1393 Comm: sh Not tainted 4.14.0-rc1-00034-g5aa83fb178e3 #1528 [ 346.587914] task: ffff899d3a3327c0 task.stack: ffff9e6600888000 [ 346.594530] RIP: 0010:kernfs_find_ns+0xe/0xc0 [ 346.599395] RSP: 0000:ffff9e660088ba28 EFLAGS: 00010246 [ 346.605229] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 346.613199] RDX: 0000000000000000 RSI: ffffffff90cab2c1 RDI: 0000000000000000 [ 346.621168] RBP: ffff9e660088ba48 R08: 0000000000000000 R09: 000000018040003d [ 346.629139] R10: ffff9e660088ba68 R11: ffff899d3b080e00 R12: ffffffff90cab2c1 [ 346.637107] R13: 0000000000000000 R14: ffff899d310b04a8 R15: ffff899d39cdcd70 [ 346.645079] FS: 0000000000000000(0000) GS:ffff899d3fc00000(0063) knlGS:00000000f7f2d690 [ 346.654118] CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 [ 346.660536] CR2: 0000000000000070 CR3: 0000000171173000 CR4: 00000000003406f0 [ 346.668504] Call Trace: [ 346.671237] kernfs_find_and_get_ns+0x2c/0x50 [ 346.676106] sysfs_unmerge_group+0x18/0x60 [ 346.680683] dpm_sysfs_remove+0x1d/0x60 [ 346.684969] device_del+0xef/0x2e0 [ 346.688765] ? cdev_del+0x22/0x30 [ 346.692470] mmc_blk_remove_parts.isra.28+0x6c/0xf0 [ 346.697919] mmc_blk_remove+0x27/0x190 [ 346.702106] mmc_bus_remove+0x18/0x20 [ 346.706197] device_release_driver_internal+0x142/0x200 [ 346.712036] device_release_driver+0xd/0x10 [ 346.716709] bus_remove_device+0xdb/0x120 [ 346.721188] device_del+0x1c3/0x2e0 [ 346.725083] mmc_remove_card+0x5b/0xc0 [ 346.729270] mmc_remove+0x14/0x30 [ 346.732974] mmc_stop_host+0xef/0x1a0 [ 346.737065] mmc_remove_host+0x15/0x40
