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SubjectRe: [uml-devel] fuzz tested 32 bit user mode linux image hangs in radix_tree_next_chunk()
Am 10.11.2013 16:14, schrieb Toralf Förster:
> On 11/06/2013 10:31 PM, Richard Weinberger wrote:
>> Am 06.11.2013 22:18, schrieb Toralf Förster:
>>> On 11/06/2013 05:06 PM, Konstantin Khlebnikov wrote:
>>>> In this case it must stop after scanning whole tree in line:
>>>> /* Overflow after ~0UL */
>>>> if (!index)
>>>> return NULL;
>>>>
>>>
>>> A fresh current example with latest git tree shows that lines 769 and 770 do alternate :
>>
>> Can you please ask gdb for the value of offset?
>>
>> Thanks,
>> //richard
>>
>
> With this change
>
> diff --git a/lib/radix-tree.c b/lib/radix-tree.c
> index 7811ed3..b2e9db5 100644
> --- a/lib/radix-tree.c
> +++ b/lib/radix-tree.c
> @@ -767,6 +767,7 @@ restart:
> offset + 1);
> else
> while (++offset < RADIX_TREE_MAP_SIZE) {
> + printk ("node->slots[offset] %p offeset %lu\n", node->slots[offset], offset);
> if (node->slots[offset])
> break;
> }

Make sure that you print only in case of a enless loop. i.e. add a loop counter
and start printing only if the loop was taken *very* often.

Thanks,
//richard
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