Re: [staging] 184ecc5ceb: BUG:unable_to_handle_kernel

[NeilBrown]

On Mon, Mar 19 2018, kernel test robot wrote:

> FYI, we noticed the following commit (built with gcc-6):
>
> commit: 184ecc5ceb379b43b29fc373f497fca88c73ad38 ("staging: lustre: allow monolithic builds")
> https://git.kernel.org/cgit/linux/kernel/git/gregkh/staging.git staging-testing
>
> in testcase: trinity
> with following parameters:
>
> 	runtime: 300s
>
> test-description: Trinity is a linux system call fuzz tester.
> test-url: http://codemonkey.org.uk/projects/trinity/
>
>
> on test machine: qemu-system-i386 -enable-kvm -smp 2 -m 320M
>
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
>
>
> +------------------------------------------+------------+------------+
> |                                          | 26f7a294e5 | 184ecc5ceb |
> +------------------------------------------+------------+------------+
> | boot_successes                           | 14         | 4          |
> | boot_failures                            | 0          | 12         |
> | BUG:unable_to_handle_kernel              | 0          | 12         |
> | Oops:#[##]                               | 0          | 12         |
> | EIP:cfs_cpt_spread_node                  | 0          | 12         |
> | Kernel_panic-not_syncing:Fatal_exception | 0          | 12         |
> +------------------------------------------+------------+------------+
>
>
>
> [  123.548190] BUG: unable to handle kernel NULL pointer dereference at 00000008
> [  123.551023] IP: cfs_cpt_spread_node+0x31/0x100

Thanks.
This happens when both USERIO and LNET are built into the kernel
drivers/staging/lustre/TODO says
  LNET_MINOR conflicts with USERIO_MINOR

I'll add a Kconfig rule preventing them from being built together until
this is resolved properly.
I'll also lok into making the module init routine more robust.

Thanks,

NeilBrown

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