RFR 8191278: MappedByteBuffer bulk access memory failures are not handled gracefully

[Jamsheed]

Hi Nick,

i could reproduce the sigsegv. was using slowdebug bits today morning, 
and so it didn't fail.

code [1] is reason for the failure.

Best regards,

Jamsheed

[1]

   void _Copy_conjoint_jlongs_atomic(jlong* from, jlong* to, size_t count) {
     if (from > to) {
       jlong *end = from + count;
       while (from < end)
         os::atomic_copy64(from++, to++);
     }
     else if (from < to) {
       jlong *end = from;
       from += count - 1;
       to   += count - 1;
       while (from >= end)
         os::atomic_copy64(from--, to--);
     }
   }

   static void atomic_copy64(const volatile void *src, volatile void *dst) {
       *(jlong *) dst = *(const jlong *) src;
    }



On 09/04/19 1:22 PM, Jamsheed wrote:
> Hi Nick,
>
> On 08/04/19 4:52 PM, Nick Gasson wrote:
>> Hi Jamsheed,
>>
>> On 05/04/2019 21:11, Jamsheed wrote:
>>>
>>> webrev: http://cr.openjdk.java.net/~jcm/8191278/webrev.04/
>>>
>>> test don't pass in aarch64 in any modes in the machine i tested. so 
>>> disabled the test for aarch64.
>>>
>>
>> What failure do you get? I just tried your patch on AArch64 now and 
>> it passes on my system (after removing the @requires line ;-).
> Thank you for looking at this.
>
> i see it passing for all the modes now. not sure , what changed.
>
> used to get sigsegv(saying not mapped area) before. could be errors 
> while using hardcoded nos in size.
>
> Best regards,
>
> Jamsheed
>
>>
>>
>> Nick
>>