On 7/10/19 9:56 AM, Ville Syrjälä wrote:
On Wed, Jul 10, 2019 at 09:47:11AM -0400, Tony Camuso wrote:
On 5/24/19 4:36 AM, Jani Nikula wrote:
On Thu, 23 May 2019, tcamuso <tcamuso@xxxxxxxxxx> wrote:
From Daniel Kwon <dkwon@xxxxxxxxxx>
The system was crashed due to invalid memory access while trying to access
auxiliary device.
crash> bt
PID: 9863 TASK: ffff89d1bdf11040 CPU: 1 COMMAND: "ipmitool"
#0 [ffff89cedd7f3868] machine_kexec at ffffffffb0663674
#1 [ffff89cedd7f38c8] __crash_kexec at ffffffffb071cf62
#2 [ffff89cedd7f3998] crash_kexec at ffffffffb071d050
#3 [ffff89cedd7f39b0] oops_end at ffffffffb0d6d758
#4 [ffff89cedd7f39d8] no_context at ffffffffb0d5bcde
#5 [ffff89cedd7f3a28] __bad_area_nosemaphore at ffffffffb0d5bd75
#6 [ffff89cedd7f3a78] bad_area at ffffffffb0d5c085
#7 [ffff89cedd7f3aa0] __do_page_fault at ffffffffb0d7080c
#8 [ffff89cedd7f3b10] do_page_fault at ffffffffb0d70905
#9 [ffff89cedd7f3b40] page_fault at ffffffffb0d6c758
[exception RIP: drm_dp_aux_dev_get_by_minor+0x3d]
RIP: ffffffffc0a589bd RSP: ffff89cedd7f3bf0 RFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff89cedd7f3fd8
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffc0a613e0
RBP: ffff89cedd7f3bf8 R8: ffff89f1bcbabbd0 R9: 0000000000000000
R10: ffff89f1be7a1cc0 R11: 0000000000000000 R12: 0000000000000000
R13: ffff89f1b32a2830 R14: ffff89d18fadfa00 R15: 0000000000000000
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
RIP: 00002b45f0d80d30 RSP: 00007ffc416066a0 RFLAGS: 00010246
RAX: 0000000000000002 RBX: 000056062e212d80 RCX: 00007ffc41606810
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007ffc41606ec0
RBP: 0000000000000000 R8: 000056062dfed229 R9: 00002b45f0cdf14d
R10: 0000000000000002 R11: 0000000000000246 R12: 00007ffc41606ec0
R13: 00007ffc41606ed0 R14: 00007ffc41606ee0 R15: 0000000000000000
ORIG_RAX: 0000000000000002 CS: 0033 SS: 002b
----------------------------------------------------------------------------
It was trying to open '/dev/ipmi0', but as no entry in aux_dir, it returned
NULL from 'idr_find()'. This drm_dp_aux_dev_get_by_minor() should have done a
check on this, but had failed to do it.
I think the better question is, *why* does the idr_find() return NULL? I
don't think it should, under any circumstances. I fear adding the check
here papers over some other problem, taking us further away from the
root cause.
Also, can you reproduce this on a recent upstream kernel? The aux device
nodes were introduced in kernel v4.6. Whatever you reproduced on v3.10
is pretty much irrelevant for upstream.
BR,
Jani.
I have not been able to reproduce this problem.
mknod /dev/foo c <drm_dp_aux major> 255
cat /dev/foo
should do it.
How do I determine <drm_dp_aux major>?
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