Re: Kernel panic with 4.16-rc1 (and 4.16-rc2) running selftest

[Randy Dunlap <rdunlap@infradead.org>]

[add Matthew Wilcox; hopefully he can look/see]

On 02/23/2018 04:13 PM, Cong Wang wrote:
> On Fri, Feb 23, 2018 at 3:27 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> On Fri, Feb 23, 2018 at 11:00 AM, Randy Dunlap <rdunlap@infradead.org> wrote:
>>> [adding netdev]
>>>
>>> On 02/23/2018 08:05 AM, Khalid Aziz wrote:
>>>> I am seeing a kernel panic with 4.16-rc1 and 4.16-rc2 kernels when running selftests
>>>> from tools/testing/selftests. Last messages from selftest before kernel panic are:
>>>>
>> ...
>>>> Same selftest does not cause panic on 4.15. git bisect pointed to commit 6ce711f2750031d12cec91384ac5cfa0a485b60a ("idr: Make 1-based IDRs more efficient").
>>>> Kernel config is attached.
>>
>> Looks like something horribly wrong with u32 key id idr...
> 
> Adding a few printk's, I got:
> 
> [   31.231560] requested handle = ffe00000
> [   31.232426] allocated handle = 0
> ...
> [   31.246475] requested handle = ffd00000
> [   31.247555] allocated handle = 1
> 
> 
> So the bug is here where we can't allocate a specific handle:
> 
>                         err = idr_alloc_u32(&tp_c->handle_idr, ht, &handle,
>                                             handle, GFP_KERNEL);
>                         if (err) {
>                                 kfree(ht);
>                                 return err;
>                         }
> 


-- 
~Randy