[aarch64-port-dev ] RFR(S): 8248851: CMS: Missing memory fences between free chunk check and klass read

David Holmes david.holmes at oracle.com
Thu Jul 16 09:16:04 UTC 2020


Hi Felix,

Seems to me that you want OrderAccess::loadload() barriers to order the 
loads, not OrderAccess::acquire(). You should only use acquire semantics 
to pair with a corresponding release operation.

Cheers,
David

On 16/07/2020 7:01 pm, Yangfei (Felix) wrote:
> Ping ...
> Could someone please take another look? Especially the two webrevs for 11u & 13u.
> 
> Thanks,
> Felix
> 
>> -----Original Message-----
>> From: Yangfei (Felix)
>> Sent: Friday, July 10, 2020 7:44 PM
>> To: 'Andrew Haley' <aph at redhat.com>; Kim Barrett
>> <kim.barrett at oracle.com>
>> Cc: jdk8u-dev at openjdk.java.net; hotspot-gc-dev at openjdk.java.net;
>> aarch64-port-dev at openjdk.java.net; jdk-updates-dev at openjdk.java.net
>> Subject: RE: [aarch64-port-dev ] RFR(S): 8248851: CMS: Missing memory
>> fences between free chunk check and klass read
>>
>> Hi,
>>
>>> -----Original Message-----
>>> From: Andrew Haley [mailto:aph at redhat.com]
>>> Sent: Wednesday, July 8, 2020 5:48 PM
>>> To: Kim Barrett <kim.barrett at oracle.com>; Yangfei (Felix)
>>> <felix.yang at huawei.com>
>>> Cc: jdk8u-dev at openjdk.java.net; hotspot-gc-dev at openjdk.java.net;
>>> aarch64-port-dev at openjdk.java.net
>>> Subject: Re: [aarch64-port-dev ] RFR(S): 8248851: CMS: Missing memory
>>> fences between free chunk check and klass read
>>>
>>> On 08/07/2020 09:41, Kim Barrett wrote:
>>>>> Since CMS is deprecated from JDK9, I am not sure if it's
>>>>> appropriate to fix
>>> this issue for those JDK9+ versions.
>>>> Deprecated != unsupported.
>>>>
>>>
>>> Yes, it must be done. Thanks.
>>
>> CCing to jdk-updates-dev.
>>
>> I have prepared another two webrevs for jdk11u and jdk13u:
>>    Jdk11u-dev:  http://cr.openjdk.java.net/~fyang/8248851-11u/
>>    Jdk13u-dev: http://cr.openjdk.java.net/~fyang/8248851-13u/
>>
>> The only difference lies in copyright year update.  Both tiere1-3 tested on
>> aarch64-linux-gnu.
>> I will put jdk11u-fix-request and jdk13u-fix-request label on the issue if they
>> are good.
>>
>> I have also prepared a new webrev for jdk8u incorporating copyright year
>> update:
>>    Jdk8u-dev: http://cr.openjdk.java.net/~fyang/8248851-8u/
>>
>> Thanks,
>> Felix
>>
> 


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