Re: [linus:master] [kobject] 1b28cb81da: canonical_address#:#[##]

[Greg Kroah-Hartman]

On Wed, Feb 07, 2024 at 02:42:43PM +0800, kernel test robot wrote:
> 
> 
> Hello,
> 
> kernel test robot noticed "canonical_address#:#[##]" on:
> 
> commit: 1b28cb81dab7c1eedc6034206f4e8d644046ad31 ("kobject: Remove redundant checks for whether ktype is NULL")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> 
> [test failed on linus/master 54be6c6c5ae8e0d93a6c4641cb7528eb0b6ba478 (v6.8-rc3)]
> [test failed on linux-next/master 076d56d74f17e625b3d63cf4743b3d7d02180379]
> 
> in testcase: boot
> 
> compiler: gcc-11
> test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
> 
> (please refer to attached dmesg/kmsg for entire log/backtrace)
> 
> 
> 
> we noticed this issue is very random, as below, observed 4 times out of 68 runs.
> but we didn't see in on parent.

Ok, this is odd, but a good enough reason to revert this for now.  I was
worried about it, and this confirms my worry that there's some codepath
we aren't taking into account here that those checks were protecting us
from doing bad things.

thanks for the report, and Zhen, if you want to dig into this and see if
you can figure out what is happening so that you can submit your change
again, that would be great.

greg k-h