pcie hot plug issue.

[linuxbest]

test script

#!/bin/bash

dmesg -n 8
insmod ./u-dma-buf.ko udmabuf0=0x20000 info_enable=3 udmabuf_bind0="pci/0000:00:05.0"
echo 1 > /sys/devices/pci0000:00/0000:00:05.0/remove
rmmod u-dma-buf


panic log

ubuntu login: [ 44.600418] u_dma_buf: loading out-of-tree module taints kernel.
[ 44.601119] u_dma_buf: module verification failed: signature and/or required key missing - tainting kernel
[ 44.604621] u-dma-buf udmabuf0: driver version = 5.2.0
[ 44.605062] u-dma-buf udmabuf0: major number = 241
[ 44.605527] u-dma-buf udmabuf0: minor number = 0
[ 44.605903] u-dma-buf udmabuf0: phys address = 0x0000000001160000
[ 44.606562] u-dma-buf udmabuf0: buffer size = 131072
[ 44.607061] u-dma-buf udmabuf0: dma device = 0000:00:05.0
[ 44.607643] u-dma-buf udmabuf0: dma bus = pci
[ 44.608108] u-dma-buf udmabuf0: dma coherent = 1
[ 44.608516] u-dma-buf udmabuf0: dma mask = 0x00000000ffffffff
[ 44.608951] u-dma-buf udmabuf0: iommu domain = NONE
[ 44.609308] u-dma-buf udmabuf0: mmap mode = 3
[ 44.609641] u-dma-buf udmabuf0: mmap = dma_mmap_coherent
[ 44.610105] u-dma-buf: udmabuf0 installed.
[ 44.615053] ------------[ cut here ]------------
[ 44.615463] sysfs group 'power' not found for kobject 'udmabuf0'
[ 44.616014] WARNING: CPU: 0 PID: 823 at fs/sysfs/group.c:279 sysfs_remove_group+0x7b/0x80
[ 44.616709] Modules linked in: u_dma_buf(OE-) 9p fscache netfs binfmt_misc nls_iso8859_1 ppdev 9pnet_virtio joydev input_leds 9pnet serio_raw parport_pc parport efi_pstore dm_multipath drm scsi_dh_rdac sch_fq_codel scsi_dh_emc scsi_dh_alua ip_tables x_tables autofsy
[ 44.620082] CPU: 0 PID: 823 Comm: rmmod Tainted: G OE 5.15.0-127-generic #137-Ubuntu
[ 44.620963] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
[ 44.621666] RIP: 0010:sysfs_remove_group+0x7b/0x80
[ 44.622121] Code: ff ff 5b 41 5c 41 5d 5d c3 cc cc cc cc 4c 89 e7 e8 9a b1 ff ff eb ca 49 8b 55 00 48 8b 33 48 c7 c7 b0 84 e1 84 e8 72 a8 8c 00 <0f> 0b eb d4 90 0f 1f 44 00 00 55 48 89 e5 41 57 41 89 cf 41 56 41
[ 44.623899] RSP: 0018:ffffb2068095fca0 EFLAGS: 00010286
[ 44.624354] RAX: 0000000000000000 RBX: ffffffff84ad33a0 RCX: 0000000000000027
[ 44.625010] RDX: ffff901637c20588 RSI: 0000000000000001 RDI: ffff901637c20580
[ 44.625521] RBP: ffffb2068095fcb8 R08: 0000000000000003 R09: 0000000000000016
[ 44.626033] R10: 000000000000000a R11: 7267207366737973 R12: 0000000000000000
[ 44.626544] R13: ffff901501bb7400 R14: ffff9015008940d0 R15: 0000000000000000
[ 44.627207] FS: 00007fd685911c40(0000) GS:ffff901637c00000(0000) knlGS:0000000000000000
[ 44.627986] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 44.628492] CR2: 00005653b2af4f68 CR3: 00000001045e8000 CR4: 00000000000006f0
[ 44.629239] Call Trace:
[ 44.629505]
[ 44.629719] ? show_trace_log_lvl+0x1d6/0x2ea
[ 44.630168] ? show_trace_log_lvl+0x1d6/0x2ea
[ 44.630659] ? dpm_sysfs_remove+0x5d/0x70
[ 44.631025] ? show_regs.part.0+0x23/0x29
[ 44.631508] ? show_regs.cold+0x8/0xd
[ 44.631873] ? sysfs_remove_group+0x7b/0x80
[ 44.632403] ? __warn+0x8c/0x100
[ 44.632814] ? sysfs_remove_group+0x7b/0x80
[ 44.633329] ? report_bug+0xa4/0xd0
[ 44.633720] ? handle_bug+0x39/0x90
[ 44.634095] ? exc_invalid_op+0x19/0x70
[ 44.634484] ? asm_exc_invalid_op+0x1b/0x20
[ 44.634915] ? sysfs_remove_group+0x7b/0x80
[ 44.635359] dpm_sysfs_remove+0x5d/0x70
[ 44.635756] device_del+0xbb/0x400
[ 44.636135] ? klist_iter_exit+0x18/0x30
[ 44.636468] device_unregister+0x18/0x60
[ 44.636837] device_destroy+0x4b/0x70
[ 44.637201] udmabuf_object_destroy+0xcf/0x110 [u_dma_buf]
[ 44.637731] udmabuf_child_device_delete+0x31/0x60 [u_dma_buf]
[ 44.638244] ? udmabuf_object_destroy+0x110/0x110 [u_dma_buf]
[ 44.638726] udmabuf_device_list_remove_entry+0x7f/0x90 [u_dma_buf]
[ 44.639244] u_dma_buf_cleanup+0x29/0x8b [u_dma_buf]
[ 44.639785] u_dma_buf_exit+0x9/0x882 [u_dma_buf]
[ 44.640223] __do_sys_delete_module.constprop.0+0x187/0x290
[ 44.640698] ? exit_to_user_mode_prepare+0x37/0xb0
[ 44.641280] __x64_sys_delete_module+0x12/0x20
[ 44.641709] x64_sys_call+0x16cf/0x1fa0
[ 44.642091] do_syscall_64+0x56/0xb0
[ 44.642379] ? do_syscall_64+0x63/0xb0
[ 44.642735] ? ksys_read+0x67/0xf0
[ 44.643035] ? exit_to_user_mode_prepare+0x37/0xb0
[ 44.643396] ? syscall_exit_to_user_mode+0x2c/0x50
[ 44.643765] ? x64_sys_call+0x1dba/0x1fa0
[ 44.644079] ? do_syscall_64+0x63/0xb0
[ 44.644373] entry_SYSCALL_64_after_hwframe+0x6c/0xd6
[ 44.644858] RIP: 0033:0x7fd685a39aeb
[ 44.645242] Code: 73 01 c3 48 8b 0d 45 33 0f 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 15 33 0f 00 f7 d8 64 89 01 48
[ 44.646787] RSP: 002b:00007ffce9ea6ee8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
[ 44.647399] RAX: ffffffffffffffda RBX: 00005653b2aea760 RCX: 00007fd685a39aeb
[ 44.647920] RDX: 000000000000000a RSI: 0000000000000800 RDI: 00005653b2aea7c8
[ 44.648428] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[ 44.648996] R10: 00007fd685ad1ac0 R11: 0000000000000206 R12: 00007ffce9ea7140
[ 44.649611] R13: 00005653b2aea2a0 R14: 00007ffce9ea78d0 R15: 00005653b2aea760
[ 44.650175]
[ 44.650372] ---[ end trace 23b94e1dad743572 ]---
[ 44.653067] u-dma-buf: udmabuf0 removed.