guarantee(PageArmed == 0) failed: invaliant

[David Holmes]

Hi Yasumasa,

On 25/11/2014 1:34 PM, Yasumasa Suenaga wrote:
> Hi all,
> 
> My customer encountered crash with below messages:
> --------
> Internal Error (safepoint.cpp:309)
> guarantee(PageArmed == 0) failed: invaliant
> --------
>   - JDK: JDK6u37 x64
>   -  OS: RHEL 5.4 x86_64
> 
> I found similar issues in JBS:
>   - JDK-7116986
>   - JDK-7156454
>   - JDK-8033717
>    
> I read safepoint.cpp in jdk9, I guess this error is caused in below:
> --------
>       if (int(iterations) == DeferPollingPageLoopCount) {
>          guarantee (PageArmed == 0, "invariant") ;
>          PageArmed = 1 ;
>          os::make_polling_page_unreadable();
>       }
> --------
> 
> "iterations" is defined as "unsigned int", and increments in each loop.
> On the other hand, DeferPollingPageLoopCount is defined intx and default
> value is "-1" .
> 
> "PageArmed" sets to 1.
> --------
>    if (DeferPollingPageLoopCount < 0) {
>      // Make polling safepoint aware
>      guarantee (PageArmed == 0, "invariant") ;
>      PageArmed = 1 ;
>      os::make_polling_page_unreadable();
>    }
> --------
> 
> 
> If "iterations" is overflowed, do we encounter this guarantee ?
> I think this "if" statement should rewrite as below:

No we want this overflow to trigger the guarantee failure - it indicates
a problem elsewhere in the VM because a thread is not reaching the
safepoint that has been requested, in a timely manner.

When crashes like this occur you need to examine all the running threads
to find out which are not safepoint-safe and then determine what they
are doing and why they have not performed a safepoint check.

David
------

> --------
> diff -r 7e08ae41ddbe src/share/vm/runtime/safepoint.cpp
> --- a/src/share/vm/runtime/safepoint.cpp	Mon Nov 24 09:57:02 2014 +0100
> +++ b/src/share/vm/runtime/safepoint.cpp	Tue Nov 25 12:19:58 2014 +0900
> @@ -288,7 +288,8 @@
>         // 9. On windows consider using the return value from SwitchThreadTo()
>         //    to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
>   
> -      if (int(iterations) == DeferPollingPageLoopCount) {
> +      if ((DeferPollingPageLoopCount >= 0) &&
> +                  (int(iterations) == DeferPollingPageLoopCount)) {
>            guarantee (PageArmed == 0, "invariant") ;
>            PageArmed = 1 ;
>            os::make_polling_page_unreadable();
> --------
> 
> 
> If it is correct, I will file it to JBS and upload webrev.
> Could you help me to resolve this issue?
> 
> 
> Thanks,
> 
> Yasumasa
>