RFR: 8062672: JVM crashes during GC on various asserts which checks that HeapWord ptr is an oop

[Bengt Rutisson]

Hi again,

On 18/02/15 19:20, Bengt Rutisson wrote:
>
> Hi Stefan,
>
> On 18/02/15 10:46, Stefan Johansson wrote:
>> Hi,
>>
>> The fix for 8062672 [1] has been pushed to 7u80 and 8u60 but the 
>> patch get a small conflict when applied to 9. A bugfix only present 
>> in 9 changed one of the patched lines, but the conflict is easy to 
>> solve. A diff between the original patch (present in 7 and 8) and the 
>> resolved one shows only this diff:
>> > --- a/src/os_cpu/linux_sparc/vm/vm_version_linux_sparc.cpp
>> > +++ b/src/os_cpu/linux_sparc/vm/vm_version_linux_sparc.cpp
>> 30c30
>> < -    if (fscanf(fp, "cpu\t\t: %100[^\n]", &cpu) == 1) {
>> ---
>> > -    if (fscanf(fp, "cpu\t\t: %100[^\n]", cpu) == 1) {
>
> Hm. Your forward port looks good. So, consider it reviewed by me. But 
> the diff above kind of looks like a bug in the 7 and 8 branches to me.
>
> The change from passing &cpu to pass cpu was made by this change:
>
> JDK-8044071: Print format/argument warnings
> https://bugs.openjdk.java.net/browse/JDK-8044071
> http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/cb5694166a39
>
> But this does not look like just a simple "getting rid of a warning" 
> change. It looks to me like we will not detect Niagara correctly on 
> Linux Sparc in JDK 7 and 8. Or am I missing something?

Yes, I was missing something. The conflict is because you are completely 
replacing this code. It did not matter that the old code had a bug in it 
in JDK 7 and 8. You had replaced the buggy code there with completely 
new code. So, the bug fix made in JDK 9 is not needed in JDK 7 and 8.

Sorry, should have looked at the webrev and not just the diff in the 
email. Thanks to Mikael Vidstedt for an offline chat to discuss this. :)

Forward port looks good. Ship it!
Bengt

>
> Bengt
>
>>
>> The full webrev is available at:
>> http://cr.openjdk.java.net/~sjohanss/8062672/9/hotspot.00/
>>
>> The original review thread can be seen here:
>> http://mail.openjdk.java.net/pipermail/hotspot-dev/2014-December/016324.html 
>>
>>
>> Thanks,
>> Stefan
>>
>> [1] https://bugs.openjdk.java.net/browse/JDK-8062672
>>
>>
>