RFR(XS) 8191585 VM anonymous classes created during CDS dump time cause crash

[Ioi Lam]

Thank Harold!

- Ioi


On 3/6/18 12:43 PM, harold seigel wrote:
> Hi Ioi,
>
> The new changes look good.
>
> Thanks, Harold
>
>
> On 3/6/2018 3:15 PM, Ioi Lam wrote:
>> Hi Harold,
>>
>> Thanks for catching this. I've moved the check into do_cld() as you 
>> suggested. I also added comments in 
>> cld::is_{platform,system}_class_loader_data(), similar to the 
>> existing comments in cld::is_boot_class_loader_data().
>>
>> http://cr.openjdk.java.net/~iklam/jdk11/8191585-vm-anon-classes-cause-dumping-crash.v02/ 
>>
>>
>> Thanks
>>
>> - Ioi
>>
>>
>> On 3/6/18 11:45 AM, harold seigel wrote:
>>> Hi Ioi,
>>>
>>> This change will cause 
>>> ClassLoaderData::is_builtin_class_loader_data() to return false for 
>>> all anonymous classes except for the boot loader.
>>>
>>> Also, other callers of is_builtin_class_loader_data(), such as 
>>> Klass::class_loader_and_module_name(), probably want that function 
>>> to return true even for anonymous CLDs.
>>>
>>> Instead of changing is_platform_class_loader_data() and 
>>> is_system_class_loader_data(), could you add a !is_anonymous() check 
>>> to do_cld() ?
>>>
>>> Or, add new is_*_class_loader_data() methods that only return true 
>>> if the CLD is not anonymous?
>>>
>>> Thanks, Harold
>>>
>>>
>>> On 3/6/2018 2:20 PM, Ioi Lam wrote:
>>>> Hi,
>>>>
>>>> Please review this small VM change and the corresponding test case.
>>>>
>>>> https://bugs.openjdk.java.net/browse/JDK-8191585
>>>> http://cr.openjdk.java.net/~iklam/jdk11/8191585-vm-anon-classes-cause-dumping-crash.v01/ 
>>>>
>>>>
>>>> The crash happens in the following code:
>>>>
>>>> class CombineDictionariesClosure : public CLDClosure {
>>>>     void do_cld(ClassLoaderData* cld) {
>>>>       if (cld->is_system_class_loader_data() || 
>>>> cld->is_platform_class_loader_data()) {
>>>>         for (int i = 0; i < cld->dictionary()->table_size(); ++i) {
>>>>                                  ^^^^^^^^^^^ == NULL
>>>>
>>>> The bug is in cld->is_system_class_loader_data() -- the CLD of anon 
>>>> classes have a NULL
>>>> cld::dictionary(), but its cld::class_loader() returns the loader 
>>>> object of the holder
>>>> class.
>>>>
>>>> The fix is to reject if cld::is_anonymous() is true.
>>>>
>>>> Thanks
>>>> - Ioi
>>>
>>
>