Hello all,
I am beginning with Linux Kernel development. So I am trying to make
the IIO tasks posted on kernelnewbies DOT org.
But I got stuck with this problem that I am describing you hereafter
hoping that someone could bring me any feedback.
Many thanks,
Miguel ROBLES
----------
DESCRIPTION
-----------
After loading the corresponding IIO modules and mountig the configfs filesystem
I can not create an instance device with mkdir using the command:
$ sudo mkdir /config/iio/devices/dummy/my_dummy_device
Killed
I get the "Killed" message and looking at my syslog file, I got the warning
"refcount_t: increment on 0; use-after-free" followed by an "Oops" message.
When trying to execute the command one more time, the execution never finishes.
------
CONTEXT
-------
- Tried on 2 linux kernel releases:
- kernel: 4.10 (commit: 4977ab6)
- Kernel: 4.11 (commit: ec3b93a)
- Compiled with config file including the following options for IIO:
#
# IIO dummy driver
#
CONFIG_IIO_DUMMY_EVGEN=m
CONFIG_IIO_SIMPLE_DUMMY=m
CONFIG_IIO_SIMPLE_DUMMY_EVENTS=y
CONFIG_IIO_SIMPLE_DUMMY_BUFFER=y
CONFIG_IIO_CONFIGFS=m
- Modules loaded on following order:
/fs/configfs/configfs.ko
/drivers/iio/industrialio-configfs.ko
/drivers/iio/industrialio-sw-device.ko
/drivers/iio/industrialio-triggered-event.ko
/drivers/iio/dummy/iio_dummy_evgen.ko
/drivers/iio/dummy/iio_dummy.ko
-----
TRACE
-----
WARNING: CPU: 7 PID: 676 at lib/refcount.c:114 refcount_inc+0x37/0x40
refcount_t: increment on 0; use-after-free.
Modules linked in: iio_dummy(E) iio_dummy_evgen(E) industrialio_sw_device(E)
industrialio_configfs(E) configfs(E) binfmt_misc vmw_vsock_vmci_transport ...
CPU: 7 PID: 676 Comm: mkdir Tainted: G E 4.11.0-rc1+ #4
Call Trace:
dump_stack+0x63/0x90
__warn+0xcb/0xf0
warn_slowpath_fmt+0x5f/0x80
refcount_inc+0x37/0x40
config_item_get+0x1b/0x30 [configfs]
link_obj+0x42/0x50 [configfs]
link_group+0x19/0x70 [configfs]
configfs_mkdir+0x168/0x3d0 [configfs]
vfs_mkdir+0x10c/0x1b0
SyS_mkdir+0xd0/0x100
entry_SYSCALL_64_fastpath+0x1e/0xad
RIP: 0033:0x7f29650b33f7
RSP: 002b:00007ffcdd8babe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007ffcdd8baed8 RCX: 00007f29650b33f7
RDX: 0000000000000000 RSI: 00000000000001ff RDI: 00007ffcdd8bb82f
RBP: 0000000000000002 R08: 00000000000001ff R09: 0000000000402b00
R10: 00000000000001e5 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
---[ end trace 71ffa6eaa306d186 ]---
BUG: unable to handle kernel paging request at ffffffffffffffb8
IP: link_obj+0x9/0x50 [configfs]
PGD 2d8e0c067
PUD 2d8e0e067
PMD 0
Oops: 0002 [#1] SMP
Modules linked in: iio_dummy(E) iio_dummy_evgen(E) industrialio_sw_device(E)
industrialio_con figfs(E) configfs(E) binfmt_misc vmw_vsock_vmci_transport ...
CPU: 7 PID: 676 Comm: mkdir Tainted: G W E 4.11.0-rc1+ #4
Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5 TH/Z170X-UD5 TH-CF, BIOS F2 09/04/2015
task: ffff9b5d4267e580 task.stack: ffffa71982eb8000
RIP: 0010:link_obj+0x9/0x50 [configfs]
RSP: 0018:ffffa71982ebbe10 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff9b5be8404250 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffffffffffffff88 RDI: ffff9b5be8404250
RBP: ffffa71982ebbe38 R08: 0000000000000001 R09: 00000000000003fe
R10: 0000000000000004 R11: 00000000000003fe R12: ffffffffffffff88
R13: ffff9b5be84042b8 R14: ffff9b5d7b53b540 R15: ffff9b5be8404250
FS: 00007f29657a8800(0000) GS:ffff9b5d91dc0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffb8 CR3: 000000043fa94000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
? link_group+0x19/0x70 [configfs]
link_group+0x45/0x70 [configfs]
configfs_mkdir+0x168/0x3d0 [configfs]
vfs_mkdir+0x10c/0x1b0
SyS_mkdir+0xd0/0x100
entry_SYSCALL_64_fastpath+0x1e/0xad
RIP: 0033:0x7f29650b33f7
RSP: 002b:00007ffcdd8babe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007ffcdd8baed8 RCX: 00007f29650b33f7
RDX: 0000000000000000 RSI: 00000000000001ff RDI: 00007ffcdd8bb82f
RBP: 0000000000000002 R08: 00000000000001ff R09: 0000000000402b00
R10: 00000000000001e5 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Code: 8b 7a 48 4c 89 ee e8 f7 fd ff ff 48 8b 73 48 41 89 c6 eb 87 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 85 ff <48> 89 7e 30 48 89 e5 53 48 89 f3 74 2f e8 a5 28 00 00 48 89 43
RIP: link_obj+0x9/0x50 [configfs] RSP: ffffa71982ebbe10
CR2: ffffffffffffffb8
---[ end trace 71ffa6eaa306d187 ]---
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