RFR(M): 8169373: Work around linux NPTL stack guard error.

[David Holmes]

Hi Goetz,

As per the bug report, this issue was already known (6675312) and we 
chose not to try and address it due to no reported issues at the time. 
While I see that you have encountered an issue (is it real or 
fabricated?) I think this change is too intrusive to be applied at this 
stage of the JDK 9 release cycle, as it will change the stack 
requirements of every application running on Linux.

Thanks,
David

On 11/11/2016 1:58 AM, Lindenmaier, Goetz wrote:
> Hi,
>
>
>
> Please review this change. I please need a sponsor:
>
> http://cr.openjdk.java.net/~goetz/wr16/8169373-ppc-stackFix/webrev.01/
>
>
>
> In the Linux NPTL pthread implementation the guard size mechanism is not
> implemented properly. The posix standard requires to add the size of the
> guard pages to the stack size, instead Linux takes the space out of
> 'stacksize'.
>
> The Posix standard http://pubs.opengroup.org/onlinepubs/9699919799/
>  says "the implementation allocates extra memory at the overflow end of
> the stack". The linux man page
> https://linux.die.net/man/3/pthread_attr_setguardsize says "As at glibc
> 2.8, the NPTL threading implementation includes the guard area within
> the stack size allocation, rather than allocating extra space at the end
> of the stack, as POSIX.1 requires".
>
> I encounter this problem in runtime/Thread/TooSmallStackSize.java on ppc
> with 64K pages. _compiler_thread_min_stack_allowed is 128K on ppc, and
> ppc specifies two OS guard pages. The VM crashes in pthread creation
> because there is no usable space in the thread stack after allocating
> the guard pages.
>
> But TooSmallStackSize.java requires that the VM comes up with the stack
> size mentioned in the error message.
>
> This fix adapts the requested stack size on Linux by the size of the
> guard pages to mimick proper behaviour, see change to os_linux.cpp.
>
>
>
> The change also streamlines usage of stack_guard_page on linuxppc,
> linuxppcle, aixppc and linuxs390.
>
>
>
> To reproduce the error on linux_x86_64, apply below patch and call the
> VM with -XX:CompilerThreadStackSize=64.
>
>
>
> I’m still exploring why I had to choose such big compiler stacks on ppc
> to get –version passing, but I wanted to send the RFR now as people
> obviously looked at the bug I opened (Thanks David!).
>
>
>
> Best regards,
>
>   Goetz.
>
>
>
>
>
>
>
> diff -r b7ae012c55c3 src/os_cpu/linux_x86/vm/os_linux_x86.cpp
>
> --- a/src/os_cpu/linux_x86/vm/os_linux_x86.cpp  Mon Nov 07 12:37:28 2016
> +0100
>
> +++ b/src/os_cpu/linux_x86/vm/os_linux_x86.cpp  Thu Nov 10 16:52:17 2016
> +0100
>
> @@ -701,7 +701,7 @@
>
> size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
>
>    // Creating guard page is very expensive. Java thread has HotSpot
>
>    // guard page, only enable glibc guard page for non-Java threads.
>
> -  return (thr_type == java_thread ? 0 : page_size());
>
> +  return (thr_type == java_thread ? 0 : 64*K);
>
> }
>
>
>
> // Java thread:
>