RFR(M): 8169373: Work around linux NPTL stack guard error.
Lindenmaier, Goetz
goetz.lindenmaier at sap.com
Wed Nov 30 07:57:28 UTC 2016
Hi Dan,
> Thumbs up! I don't need to see a new webrev if you choose
> to fix the minor comments above.
I anyways did a new one fixing the comments:
http://cr.openjdk.java.net/~goetz/wr16/8169373-ppc-stackFix/webrev.06/
Would you mind sponsoring this change?
I took the minimum stack sizes from my experimental runs where
I had removed the automatic resizing to find the really needed space.
If I put something smaller there, I could as well put '0' ... as
_java_thread_min_stack_allowed = MAX2(_java_thread_min_stack_allowed,
JavaThread::stack_guard_zone_size() +
JavaThread::stack_shadow_zone_size() +
(4 * BytesPerWord COMPILER2_PRESENT(+ 2)) * 4 * K);
will fix it.
This code effectively limits the usable stack size to
(4 * BytesPerWord COMPILER2_PRESENT(+ 2)) * 4 * K)
which makes the initialization of _java_thread_min_stack_allowed with platform
values pointless.
I'll open a new bug for the follow-up stack issue, probably tomorrow.
I don't feel like addressing testing all the possible error codes, as
they probably should be fixed in more places, and there is no issue
pending currently. Maybe it should be fixed in jdk10 at some point.
Best regards,
Goetz
> -----Original Message-----
> From: Daniel D. Daugherty [mailto:daniel.daugherty at oracle.com]
> Sent: Dienstag, 29. November 2016 20:04
> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; hotspot-compiler-
> dev at openjdk.java.net; 'hotspot-runtime-dev at openjdk.java.net' <hotspot-
> runtime-dev at openjdk.java.net>
> Subject: Re: RFR(M): 8169373: Work around linux NPTL stack guard error.
>
> On 11/29/16 2:30 AM, Lindenmaier, Goetz wrote:
> > Hi Dan,
> >
> > see my replies inline ...
> > New webrev:
> > http://cr.openjdk.java.net/~goetz/wr16/8169373-ppc-stackFix/webrev.05/
>
> src/os/aix/vm/os_aix.cpp
> L887: // libc guard page
> nit - You made other existing comments into sentences (leading
> capital and trailing '.'), but not this new comment. Why?
>
> src/os/aix/vm/os_aix.hpp
> No comments.
>
> src/os/linux/vm/os_linux.cpp
> L6096: // | |/ 1 page glibc guard.
> nit - "1 page glibc guard" -> "1 glibc guard page."
>
> src/os/posix/vm/os_posix.cpp
> No comments.
>
> src/os_cpu/aix_ppc/vm/os_aix_ppc.cpp
> No comments.
>
> src/os_cpu/bsd_x86/vm/os_bsd_x86.cpp
> L875: // | |/ 1 page glibc guard.
> nit - "1 page glibc guard" -> "1 glibc guard page."
>
> src/os_cpu/linux_aarch64/vm/os_linux_aarch64.cpp
> No comments.
>
> src/os_cpu/linux_ppc/vm/os_linux_ppc.cpp
> No comments.
>
> src/os_cpu/linux_s390/vm/os_linux_s390.cpp
> No comments.
>
> src/os_cpu/linux_sparc/vm/os_linux_sparc.cpp
> No comments.
>
> src/os_cpu/linux_x86/vm/os_linux_x86.cpp
> No comments.
>
> src/os_cpu/linux_zero/vm/os_linux_zero.cpp
> No comments.
>
>
> Thumbs up! I don't need to see a new webrev if you choose
> to fix the minor comments above.
>
> Some replies embedded below.
>
>
> >
> >> -----Original Message-----
> >> From: Daniel D. Daugherty [mailto:daniel.daugherty at oracle.com]
> >> Sent: Dienstag, 29. November 2016 01:38
> >> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; hotspot-compiler-
> >> dev at openjdk.java.net; 'hotspot-runtime-dev at openjdk.java.net' <hotspot-
> >> runtime-dev at openjdk.java.net>
> >> Subject: Re: RFR(M): 8169373: Work around linux NPTL stack guard error.
> >>
> >> On 11/28/16 2:08 AM, Lindenmaier, Goetz wrote:
> >>> Hi,
> >>>
> >>> I'm working on a fix for OS guard pages on stacks. I figured there
> >>> are VM guard pages (reserved, yellow, red) on the compiler stacks
> >>> _and_ OS guard pages. For Java threads, the OS guard pages are left
> >>> out. I think this should be done for compiler threads, too. Please
> >>> confirm.
> >>> Webrev:
> >>> http://cr.openjdk.java.net/~goetz/wr16/8169373-ppc-stackFix/webrev.04/
> >> src/os/aix/vm/os_aix.cpp
> >> L888: pthread_attr_setguardsize(&attr,
> >> os::Aix::default_guard_size(thr_type));
> >> No check or assert on the return status of this call.
> >> Is one needed?
> > I implemented this as the existing code on linux which has
> > no check either. I think a failure is quite theoretical.
> > Because of your comment below I'll leave it as-is.
>
> OK.
>
>
> >
> >> L3044: // guard pages, so only enable libc guard pages for
> >> non-Java threads.
> >> src/os/linux/vm/os_linux.cpp also has this comment:
> >> // (Remember: compiler thread is a Java thread, too!)
> > Fixed.
> >
> >> L3051: return ((thr_type == java_thread || thr_type ==
> >> compiler_thread) ? 0 : 4*K);
> >> nit - please add spaces around the '*' so '4 * K'.'
> > Fixed.
> >
> >> src/os/aix/vm/os_aix.hpp
> >> No comments.
> >>
> >> src/os/linux/vm/os_linux.cpp
> >> L729: // is not implemented properly. The posix standard requires
> >> to add
> >> Typo: 'to add' -> 'adding'
> > Fixed.
> >
> >> L738: pthread_attr_setguardsize(&attr,
> >> os::Linux::default_guard_size(thr_type));
> >> No check or assert on the return status of this call.
> >> Is one needed?
> > See above.
> >
> >> L2851: // Creating guard page is very expensive. Java thread has
> >> HotSpot
> >> L2852: // guard page, only enable glibc guard page for non-Java
> >> threads.
> >> L2853: // (Remember: compiler thread is a java thread, too!)
> >> Typo: "java thread" -> "Java thread" (consistency)
> >>
> >> This comment block should be common to all the platforms that
> >> define default_guard_size(). Yes, I can see that AIX needs to
> >> add another paragraph, but we should make the core comment
> common
> >> if possible.
> > I made the first three lines look alike.
> >
> >> L6090: // Java/Compiler thread:
> >> Thanks for making this common in os_linux.cpp.
> >>
> >> L6095: // | glibc guard page | - guard, attached Java
> >> thread usually has
> >> Clarity: "guard," -> "guard page,"
> > Fixed.
> >
> >> Typo: "Java thread" -> "JavaThread" (consistency)
> > I changed both to Java thread as at the other locations.
> >
> >> L6099: // | HotSpot Guard Pages | - red and yellow pages
> >> The fairly recently added reserved page should be mentioned
> >> here also?
> > Yes. Fixed. Also fixed it to say JavaThread::stack_reserved_zone_base().
> > Also fixed comment on bsd.
>
> Thanks for also fixing BSD.
>
>
> >> L6120 // ** P1 (aka bottom) and size ( P2 = P1 - size) are the
> >> address and stack size returned from
> >> Typo: "( P2 = ..." -> "(P2 = ..."
> > Fixed.
> >
> >> L6148: fatal("Can not locate current stack attributes!");
> >> Typo: "Can not" -> "Cannot"
> > Fixed.
> >
> >> L6175: // stack size includes normal stack and HotSpot guard pages
> >> Perhaps add to the comment:
> >> "for the threads that have HotSpot guard pages."
> > Fixed. I also checked my comments for "OS guard pages" and
> > replaced it by "glibc guard pages" which is used in several places
> > already, same for "VM guard page" --> "HotSpot guard page". I
> > think this is also more consistent.
>
> I agree!
>
>
> >> src/os/posix/vm/os_posix.cpp
> >> L1097: pthread_attr_getstacksize(attr, &stack_size);
> >> L1098: pthread_attr_getguardsize(attr, &guard_size);
> >> Do these two calls need to have their result checked?
> >>
> >> Now I'm starting to wonder if all the uses of these
> >> two APIs need to be checked? Separate bug?
> > It would be more consistent with the specification of the methods,
> > On the other side it's quite unlikely that these fail if attr != NULL.
>
> So should we file a new bug? Or does this fall into the realm of
> other OS/libc code that we call and assume never fails? :-)
>
>
> >
> >> src/os_cpu/aix_ppc/vm/os_aix_ppc.cpp
> >> L540: size_t os::Posix::_compiler_thread_min_stack_allowed = 512 * K;
> >> L541: size_t os::Posix::_java_thread_min_stack_allowed = 512 * K;
> >> So prior to the fix for 8140520, src/os/aix/vm/os_aix.cpp had
> >> this single min_stack_allowed value:
> >>
> >> L3601: os::Aix::min_stack_allowed =
> >> MAX2(os::Aix::min_stack_allowed,
> >> L3602: JavaThread::stack_guard_zone_size() +
> >> L3603: JavaThread::stack_shadow_zone_size() +
> >> L3604: (4*BytesPerWord
> >> COMPILER2_PRESENT(+2)) * 4 * K);
> >>
> >> and the fix for 8140520 changed that for *NIX platforms to
> >> three mins in src/os/posix/vm/os_posix.cpp:
> >>
> >> L1108: _java_thread_min_stack_allowed =
> >> MAX2(_java_thread_min_stack_allowed,
> >> L1109: JavaThread::stack_guard_zone_size() +
> >> L1110: JavaThread::stack_shadow_zone_size() +
> >> L1111: (4 *
> >> BytesPerWord COMPILER2_PRESENT(+ 2)) * 4 * K);
> >>
> >> L1150: _compiler_thread_min_stack_allowed =
> >> align_size_up(_compiler_thread_min_stack_allowed, vm_page_size());
> >>
> >> L1161 _vm_internal_thread_min_stack_allowed =
> >> align_size_up(_vm_internal_thread_min_stack_allowed, vm_page_size());
> >>
> >> Which means that the compiler_thread no longer benefits from
> >> the extra space for quard and shadow pages. The thinking in
> >> 8140520 was that the compiler_thread and vm_internal_threads
> >> don't need the quard and shadow pages since they don't run
> >> Java code (ignoring JVMCI for now).
> >>
> >> So I can see bumping _compiler_thread_min_stack_allowed from
> >> 128 -> 512 as one solution for getting that extra space back.
> >> However, I don't understand why _java_thread_min_stack_allowed
> >> has changed from 128 -> 512.
> > Because it was never correct before.
>
> OK. That sounds like the new test that I included with 8140520 would
> have failed with JavaThread stack sizes even before the product code
> changes from 8140520 were made.
>
> Since the size calculation for JavaThread stack sizes wasn't changed
> for any platform in 8140520, that tends to indicate that the more
> limited JDK test (test/tools/launcher/TooSmallStackSize.java) should
> also have failed before the fix for 8140520.
>
> Please clarify the need for the _java_thread_min_stack_allowed change
> from 128 -> 512. Unless test/tools/launcher/TooSmallStackSize.java
> is never run in your testing, I'm having troubling seeing why the
> _java_thread_min_stack_allowed increase is needed.
>
>
> >> I had previously made this comment:
> >> > To put it another way, I'd like to see us add extra space to
> >> > solve the 64K page issue directly instead of as a side effect
> >> > of the red/yellow page addition.
> >> And Goetz replied with:
> >> > I don't understand. What do you mean by 'directly'?
> >>
> >> So prior to the fix for 8140520, src/os/solaris/vm/os_solaris.cpp
> >> had a block like this:
> >>
> >> L4468: // For 64kbps there will be a 64kb page size, which makes
> >> L4469: // the usable default stack size quite a bit less.
> >> Increase the
> >> L4470: // stack for 64kb (or any > than 8kb) pages, this
> >> increases
> >> L4471: // virtual memory fragmentation (since we're not
> >> creating the
> >> L4472 // stack on a power of 2 boundary. The real fix for this
> >> L4473 // should be to fix the guard page mechanism.
> >> L4474
> >> L4475 if (vm_page_size() > 8*K) {
> >> L4476 threadStackSizeInBytes = (threadStackSizeInBytes != 0)
> >> L4477 ? threadStackSizeInBytes +
> >> L4478 JavaThread::stack_red_zone_size() +
> >> L4479 JavaThread::stack_yellow_zone_size()
> >> L4480 : 0;
> >> L4481 ThreadStackSize = threadStackSizeInBytes/K;
> >> L4482 }
> >>
> >> The above is an example of what I mean by solving the 64K
> >> page issue directly. In the fix for 8140520, that code block
> >> was moved to os::Posix::set_minimum_stack_sizes() in
> >> src/os/posix/vm/os_posix.cpp and put in a "#ifdef SOLARIS...
> >> #endif // SOLARIS" block. Coleen filed a bug to determine
> >> whether that code can be deleted:
> >>
> >> JDK-8161093 Solaris for >8k pagesize adds extra guard pages
> >> https://bugs.openjdk.java.net/browse/JDK-8161093
> >>
> >> but perhaps this bug shows that the code is needed?
> >>
> >>
> >> OK so this is probably the longest code review comment
> >> I have ever written, but the summary is:
> >>
> >> - I understand bumping _compiler_thread_min_stack_allowed,
> >> but should it be solved in a different way?
> >> - I don't understand bumping _java_thread_min_stack_allowed
> > I plan to do a follow up change to fix this. Let's leave this discussion
> > to that review. Here I just want to fix the NPTL issue and the basic
> > sizing that is needed to pass the new test on ppc/s390.
>
> Same question here about the simpler JDK version of the test.
>
> Does test/tools/launcher/TooSmallStackSize.java get run in
> your test environments?
>
>
> >
> >> src/os_cpu/linux_aarch64/vm/os_linux_aarch64.cpp
> >> No comments.
> >>
> >> src/os_cpu/linux_ppc/vm/os_linux_ppc.cpp
> >> L538: size_t os::Posix::_compiler_thread_min_stack_allowed = 384 * K;
> >> L539: size_t os::Posix::_java_thread_min_stack_allowed = 384 * K;
> >>
> >> Same monster comment as src/os_cpu/aix_ppc/vm/os_aix_ppc.cpp
> >> and the same summary:
> >>
> >> - I understand bumping _compiler_thread_min_stack_allowed,
> >> but should it be solved in a different way?
> >> - I don't understand bumping _java_thread_min_stack_allowed
> >>
> >> src/os_cpu/linux_s390/vm/os_linux_s390.cpp
> >> L478: size_t os::Posix::_compiler_thread_min_stack_allowed = 128 * K;
> >> L479: size_t os::Posix::_java_thread_min_stack_allowed = 236 * K;
> >> Bumping _java_thread_min_stack_allowed but not bumping
> >> _compiler_thread_min_stack_allowed. I'm confused here.
> > The numbers are what I need to startup on the machines. 128 is just
> > fine on the machines we have. (That's the problem of the
> > current setup: you have to tune this compile time constant for the
> > page size of the machine you are running on. But let's discuss this
> > in the follow up change.)
>
> OK about discussing this with a follow-up change. I guess I see
> the compile time initialization as a "minimum setting assuming the
> smallest page size". If we discover (at runtime) that the page
> size is bigger, then we adjust the minimum that we need...
>
> Again, defer to another bug. Do we have a bug ID yet?
>
>
> >> src/os_cpu/linux_sparc/vm/os_linux_sparc.cpp
> >> No comments.
> >>
> >> src/os_cpu/linux_x86/vm/os_linux_x86.cpp
> >> No comments.
> >>
> >> src/os_cpu/linux_zero/vm/os_linux_zero.cpp
> >> No comments.
> >>
> >> Sorry it took me so long to write this up...
> > No matter, thanks for this thorough review!
>
> You are very welcome. Thanks for being willing to dive into such
> a complicated area (thread stack sizes)...
>
> Dan
>
>
>
> >
> > Best regards,
> > Goetz.
> >
> >> Dan
> >>
> >>> The change affecting the compier threads is in os_linux.cpp,
> >> default_guard_size(),
> >>> where '|| thr_type == compiler_thread' has been added. The function
> >>> was also moved from the os_cpu files, as it's identical on all cpus.
> >>>
> >>> Best regards,
> >>> Goetz.
> >>>
> >>>
> >>>> -----Original Message-----
> >>>> From: David Holmes [mailto:david.holmes at oracle.com]
> >>>> Sent: Montag, 28. November 2016 00:25
> >>>> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>;
> >>>> 'daniel.daugherty at oracle.com' <daniel.daugherty at oracle.com>;
> 'hotspot-
> >>>> runtime-dev at openjdk.java.net' <hotspot-runtime-dev at openjdk.java.net>
> >>>> Subject: Re: RFR(M): 8169373: Work around linux NPTL stack guard error.
> >>>>
> >>>> Hi Goetz,
> >>>>
> >>>> On 24/11/2016 10:15 PM, Lindenmaier, Goetz wrote:
> >>>>> Hi,
> >>>>>
> >>>>> I now edited the stuff I had proposed below:
> >>>>> http://cr.openjdk.java.net/~goetz/wr16/8169373-ppc-
> stackFix/webrev.03/
> >>>>> This includes
> >>>>> - the NPTL fix from webrev.02
> >>>> Okay in principle. As discussed this only impacts non-JavaThreads so the
> >>>> change should be minimal.
> >>>>
> >>>>> - merging code on linux
> >>>> Went a bit further than I had expected but if this truly isn't CPU
> >>>> dependent code then great!
> >>>>
> >>>>> - not adding OS guard to compiler threads.
> >>>> Okay in principle. IIUC we will now save the OS guard page for compiler
> >>>> thread stacks. Is that the only impact? The hotspot-compiler-dev folk
> >>>> may want to sign off on this part.
> >>>>
> >>>>
> >>>> A few minor comments:
> >>>>
> >>>> src/os/linux/vm/os_linux.cpp
> >>>>
> >>>> 2854 return ((thr_type == java_thread || thr_type ==
> >>>> os::compiler_thread) ...
> >>>>
> >>>> os:: should be used for both types or none.
> >>>>
> >>>> 6153 pthread_attr_getguardsize(&attr, &guard_size);
> >>>>
> >>>> Can you at least verify a zero return code in an assert/assert_status
> >>>> please.
> >>>>
> >>>> ---
> >>>>
> >>>> src/os_cpu/aix_ppc/vm/os_aix_ppc.cpp
> >>>> src/os_cpu/linux_ppc/vm/os_linux_ppc.cpp
> >>>> src/os_cpu/linux_s390/vm/os_linux_s390.cpp
> >>>>
> >>>> Are the changes to min_stack_allowed just fixing an existing bug?
> >>>>
> >>>> ---
> >>>>
> >>>> Thanks,
> >>>> David
> >>>> -----
> >>>>
> >>>>
> >>>>> I think this should be pushed for this bug ID. For the other changes I'll
> >>>>> make another bug.
> >>>>>
> >>>>> Best regards,
> >>>>> Goetz.
> >>>>>
> >>>>>> -----Original Message-----
> >>>>>> From: Lindenmaier, Goetz
> >>>>>> Sent: Wednesday, November 23, 2016 8:11 AM
> >>>>>> To: David Holmes <david.holmes at oracle.com>;
> >>>>>> daniel.daugherty at oracle.com; hotspot-runtime-dev at openjdk.java.net
> >>>>>> Subject: RE: RFR(M): 8169373: Work around linux NPTL stack guard
> error.
> >>>>>>
> >>>>>> Hi,
> >>>>>>
> >>>>>>> Bzzzt! Sorry Goetz and Dan but that is no longer correct with JVMCI.
> The
> >>>>>>> ability for a CompilerThread to execute Java code (can_call_java()) is
> >>>>>>> now a dynamic property depending on whether the current compiler
> is
> >> the
> >>>>>>> JVMCI compiler.
> >>>>>> Ah, then I should also leave space for shadow pages in the minimal
> stack
> >>>> size
> >>>>>> of comiler threads.
> >>>>>>
> >>>>>> Do we agree on the cleanup and on leaving out the OS guard page on
> >>>>>> compiler threads?
> >>>>>> Then I would edit a change comprising the NPTL workaround and these
> >>>>>> additional changes, and split the other issue into a new bug? I think this
> >>>>>> will easy the reviewing.
> >>>>>>
> >>>>>> Best regards,
> >>>>>> Goetz.
> >>>>>>
> >>>>>>> -----Original Message-----
> >>>>>>> From: David Holmes [mailto:david.holmes at oracle.com]
> >>>>>>> Sent: Mittwoch, 23. November 2016 02:50
> >>>>>>> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>;
> >>>>>>> daniel.daugherty at oracle.com; hotspot-runtime-dev at openjdk.java.net
> >>>>>>> Subject: Re: RFR(M): 8169373: Work around linux NPTL stack guard
> >> error.
> >>>>>>> On 22/11/2016 11:19 PM, Lindenmaier, Goetz wrote:
> >>>>>>>> Hi Dan,
> >>>>>>>>
> >>>>>>>>> -----Original Message-----
> >>>>>>>>> From: Daniel D. Daugherty [mailto:daniel.daugherty at oracle.com]
> >>>>>>>>> Sent: Dienstag, 22. November 2016 14:01
> >>>>>>>>> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; David
> Holmes
> >>>>>>>>> <david.holmes at oracle.com>; hotspot-runtime-
> dev at openjdk.java.net
> >>>>>>>>> Subject: Re: RFR(M): 8169373: Work around linux NPTL stack guard
> >>>>>> error.
> >>>>>>>>> On 11/22/16 3:55 AM, Lindenmaier, Goetz wrote:
> >>>>>>>>>> Hi Dan,
> >>>>>>>>>>
> >>>>>>>>>> I ran into a row of issues, some errors on the platforms.
> >>>>>>>>>>
> >>>>>>>>>> What I meant with that comment is that
> >>>>>>>>>> os::Linux::min_stack_allowed =
> MAX2(os::Linux::min_stack_allowed,
> >>>>>>>>>> JavaThread::stack_guard_zone_size() +
> >>>>>>>>>> JavaThread::stack_shadow_zone_size() +
> >>>>>>>>>> (4*BytesPerWord
> >> COMPILER2_PRESENT(+2)) *
> >>>> 4
> >>>>>> *
> >>>>>>> K);
> >>>>>>>>>> was executed, and min_stack_allowed used for all stacks. Now,
> >>>>>> compiler
> >>>>>>>>> and
> >>>>>>>>>> vm minimum stack sizes are not increased by these sizes.
> >>>>>>>>> Now I see what you mean. Thanks for clearing this up.
> >>>>>>>>>
> >>>>>>>>> I should have remembered that part of the change because we
> went
> >>>>>> back
> >>>>>>>>> and forth about removing the red/yellow zone pages from the other
> >>>>>>>>> threads. In particular, we discussed the compiler thread because it
> >>>>>>>>> is-a JavaThread. Our conclusion was that a compiler thread doesn't
> >>>>>>>>> execute Java bytecode so we could remove the red/yellow pages...
> >>>>>>>> Yes, it does not execute java byte code.
> >>>>>>> Bzzzt! Sorry Goetz and Dan but that is no longer correct with JVMCI.
> The
> >>>>>>> ability for a CompilerThread to execute Java code (can_call_java()) is
> >>>>>>> now a dynamic property depending on whether the current compiler
> is
> >> the
> >>>>>>> JVMCI compiler.
> >>>>>>>
> >>>>>>> David
> >>>>>>> -----
> >>>>>>>
> >>>>>>>> Therefore you can remove the shadow pages. There is no code that
> >>>>>>>> will bang.
> >>>>>>>> But red/yellow pages are protected right during thread startup.
> >>>>>>>> Therefore you must have enough space for them.
> >>>>>>>> On ppc, we try to protect three 64K pages out of the 128K compiler
> >> stack.
> >>>>>>>> That obviously fails.
> >>>>>>>>
> >>>>>>>> Therefore I propose:
> >>>>>>>> size_t os::Posix::_java_thread_min_stack_allowed = 48 * K; //
> Set
> >>>>>>> platform dependent.
> >>>>>>>> in os::Posix::set_minimum_stack_sizes():
> >>>>>>>> _java_thread_min_stack_allowed =
> _java_thread_min_stack_allowed
> >> +
> >>>>>>>> JavaThread::stack_guard_zone_size() +
> >>>>>>>> JavaThread::stack_shadow_zone_size();
> >>>>>>>>
> >>>>>>>> (Similar for _compiler_thread_min_stack_allowed).
> >>>>>>>>
> >>>>>>>> The minimal stack size is made up of three components:
> >>>>>>>> 1. Sizes of interpreter/C1/C2 frames. Depends on HotSpot
> >>>>>>> implementation/platform/os.
> >>>>>>>> 2. Sizes of C++ frames: depends on C++ compiler.
> >>>>>>>> These are fixed at compile time.
> >>>>>>>> 3. Sizes of red/yellow/reserved/shadow pages. Depends on the
> >> system
> >>>>>>> the
> >>>>>>>> VM is used on. This is not fixed at compile time. (Our ppc
> >> machines
> >>>>>>> differ
> >>>>>>>> in page size.)
> >>>>>>>> Therefore 3. should not be included in a compile time constant.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>> And that decision allowed us to be exposed to the 64K page issue
> >>>>>>>>> because the "extra" space isn't there anymore.
> >>>>>>>>>
> >>>>>>>>>> At least the _compiler_thread_min_stack_allowed should be
> >> increased
> >>>>>>>>>> similarly by red/yellow zone size. The compiler thread is a Java
> >>>>>>>>>> thread and must have space for these zones.
> >>>>>>>>> I'm not sure that I completely agree (yet). To me, the red/yellow
> >>>>>>>>> pages are there for Java thread stack overflow semantics. Yes, the
> >>>>>>>>> compiler thread needs extra space when 64K pages are used, but I
> >>>>>>>>> would prefer that we add that space via a different calculation.
> >>>>>>>> Yes they are. But compiler threads happen tob e a subclass of
> >>>>>>>> Java threads and use the same run() method that puts the pages
> >>>>>>>> There.
> >>>>>>>> I agree that they are not needed for Compiler threads, nor for
> >>>>>>>> CodeCacheSweeperThreads. I don't really now about
> >>>>>>>> JvmtiAgentThreads and ServiceThreads, but all of the get the guard
> >>>>>> pages
> >>>>>>>> because they are derived from JavaThread.
> >>>>>>>>
> >>>>>>>>> To put it another way, I'd like to see us add extra space to solve
> >>>>>>>>> the 64K page issue directly instead of as a side effect of the
> >>>>>>>>> red/yellow page addition.
> >>>>>>>> I don't understand. What do you mean by 'directly'?
> >>>>>>>>
> >>>>>>>>>> Also, the change added a test that is failing now.
> >>>>>>>>> And that's a "good thing" (TM), right? :-)
> >>>>>>>> Yes, it showed a bug and thus raised the need to fix it! :)
> >>>>>>>>
> >>>>>>>> Best regards,
> >>>>>>>> Goetz.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>> Again, thanks for clarifying 8140520's role in this issue.
> >>>>>>>>>
> >>>>>>>>> Dan
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>> Best regards,
> >>>>>>>>>> Goetz.
> >>>>>>>>>>
> >>>>>>>>>>> -----Original Message-----
> >>>>>>>>>>> From: Daniel D. Daugherty
> [mailto:daniel.daugherty at oracle.com]
> >>>>>>>>>>> Sent: Montag, 21. November 2016 17:28
> >>>>>>>>>>> To: David Holmes <david.holmes at oracle.com>; Lindenmaier,
> Goetz
> >>>>>>>>>>> <goetz.lindenmaier at sap.com>; hotspot-runtime-
> >>>>>>> dev at openjdk.java.net
> >>>>>>>>>>> Subject: Re: RFR(M): 8169373: Work around linux NPTL stack
> guard
> >>>>>>> error.
> >>>>>>>>>>> Sorry for the delayed responses to this thread. I've been on
> >> vacation...
> >>>>>>>>>>> One comment/query embedded below...
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> On 11/10/16 8:40 PM, David Holmes wrote:
> >>>>>>>>>>>> Hi Goetz,
> >>>>>>>>>>>>
> >>>>>>>>>>>> On 11/11/2016 8:00 AM, Lindenmaier, Goetz wrote:
> >>>>>>>>>>>>> Hi David,
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> This issue is different to 6675312, see also my comment in the
> >> bug.
> >>>>>>>>>>>>> It appears running jtreg test
> >>>>>>> runtime/Thread/TooSmallStackSize.java,
> >>>>>>>>>>>>> with my patch below you can reproduce it on linuxx86_64. You
> >> can
> >>>>>>> not
> >>>>>>>>>>>>> do that with 6675312. Also, I would assume there are systems
> out
> >>>>>>> there
> >>>>>>>>>>>>> on x86 that uses 64-K pages, did you run the tests on these? I
> >>>>>> would
> >>>>>>>>>>>>> assume you get hard crashes with stack overflows in the first
> C2
> >>>>>>>>>>>>> compilation if there is only 64K usable CompilerThreadStack.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> My fix does not affect Java threads, which are the largest
> amount
> >>>>>>>>>>>>> of threads used by the VM. It affects only the non-Java threads.
> >>>>>>>>>>>>> It adds one page to these threads. The page does not require
> >>>>>>> memory,
> >>>>>>>>>>>>> as it's protected. The stack will only require more space if the
> >>>>>> thread
> >>>>>>>>>>>>> ran into a stack overflow before the fix as else the pages are
> not
> >>>>>>>>>>>>> mapped.
> >>>>>>>>>>>>> This are stack overflows that cause hard crashes, at least on
> ppc
> >>>>>> the
> >>>>>>> VM
> >>>>>>>>>>>>> does not properly catch these stack overflows, so any setup
> >>>>>> working
> >>>>>>>>> now
> >>>>>>>>>>>>> will not run into the additional space. Altogether there should
> be
> >>>>>> no
> >>>>>>>>>>>>> effect on running systems besides requiring one more entry in
> >> the
> >>>>>>>>>>>>> page table per non-Java thread.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> The problem is caused by a rather recent change (8140520:
> >>>>>> segfault
> >>>>>>> on
> >>>>>>>>>>>>> solaris-amd64
> >>>>>>>>>>>>> with "-XX:VMThreadStackSize=1" option) which was pushed
> after
> >>>>>>>>>>>>> feature-close. As this was a rather recent change, it must be
> >>>>>>>>>>>>> possible to
> >>>>>>>>>>>>> fix this follow up issue. What else is this period in the project
> >> good
> >>>>>>>>>>>>> for if not fixing issues?
> >>>>>>>>>>>> So I am seeing a number of factors here.
> >>>>>>>>>>>>
> >>>>>>>>>>>> First, 8140520, set:
> >>>>>>>>>>>>
> >>>>>>>>>>>> size_t os::Posix::_compiler_thread_min_stack_allowed = 128 *
> K;
> >>>>>>>>>>> So I'm confused by the above comment:
> >>>>>>>>>>>
> >>>>>>>>>>> > The problem is caused by a rather recent change (8140520:
> >>>>>> segfault
> >>>>>>>>>>> > on solaris-amd64 with "-XX:VMThreadStackSize=1" option)
> >>>>>>>>>>>
> >>>>>>>>>>> http://cr.openjdk.java.net/~dcubed/8140520-webrev/5-jdk9-hs-
> >>>>>>>>>>>
> >>>>>>> open/hotspot/src/os_cpu/linux_ppc/vm/os_linux_ppc.cpp.frames.html
> >>>>>>>>>>> shows this change:
> >>>>>>>>>>>
> >>>>>>>>>>> @@ -531,19 +531,17 @@
> >>>>>>>>>>> }
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>
> //////////////////////////////////////////////////////////////////////////////
> >>>>>>>>>>> //
> >>>>>>>>>>> // thread stack
> >>>>>>>>>>>
> >>>>>>>>>>> -size_t os::Linux::min_stack_allowed = 128*K;
> >>>>>>>>>>> +size_t os::Posix::_compiler_thread_min_stack_allowed = 128 *
> K;
> >>>>>>>>>>> +size_t os::Posix::_java_thread_min_stack_allowed = 128 * K;
> >>>>>>>>>>> +size_t os::Posix::_vm_internal_thread_min_stack_allowed = 128
> *
> >> K;
> >>>>>>>>>>> so the existing single variable of 'min_stack_allowed' was
> >>>>>>>>>>> replaced by three variables:
> _compiler_thread_min_stack_allowed,
> >>>>>>>>>>> _java_thread_min_stack_allowed, and
> >>>>>>>>>>> _vm_internal_thread_min_stack_allowed.
> >>>>>>>>>>>
> >>>>>>>>>>> The old single variable and the three new variables are all
> >>>>>>>>>>> initialized to the same value (128K) so the fix for 8140520
> >>>>>>>>>>> did not change stack sizes for this platform. In fact, only
> >>>>>>>>>>> one platform had a size change (Solaris X64).
> >>>>>>>>>>>
> >>>>>>>>>>> So I'm confused about how the fix for 8140520 caused this
> problem.
> >>>>>>>>>>>
> >>>>>>>>>>> Based on David's analysis below, it looks to me like this 64K stack
> >>>>>>>>>>> guard page problem should also exist prior to the fix for
> 8140520.
> >>>>>>>>>>>
> >>>>>>>>>>> Goetz, can you please explain how 8140520 caused this problem?
> >>>>>>>>>>>
> >>>>>>>>>>> Dan
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>> Second on linux PPC it is hardwired to use 2 guard pages:
> >>>>>>>>>>>>
> >>>>>>>>>>>> return 2 * page_size();
> >>>>>>>>>>>>
> >>>>>>>>>>>> Third, you had a pagesize of 64K.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Fourth, NPTL takes the guard space from the stack space -
> hence
> >>>>>> with
> >>>>>>> 2
> >>>>>>>>>>>> x 64K guard, and a 128K stack it was all consumed.
> >>>>>>>>>>>>
> >>>>>>>>>>>> ---
> >>>>>>>>>>>>
> >>>>>>>>>>>> In the proposed changes you now only use page_size() for the
> >> guard,
> >>>>>>> so
> >>>>>>>>>>>> that alone would have fixed the observed problem.
> >>>>>>>>>>>>
> >>>>>>>>>>>> But in addition you want to address the NPTL problem by adding
> >>>>>> back
> >>>>>>>>>>>> the guard space to the stack size requested. That alone would
> also
> >>>>>>>>>>>> have fixed the observed problem. :)
> >>>>>>>>>>>>
> >>>>>>>>>>>> But in addition you have increased the minimum stack size:
> >>>>>>>>>>>>
> >>>>>>>>>>>> ! size_t os::Posix::_compiler_thread_min_stack_allowed = 192 *
> K;
> >>>>>>>>>>>>
> >>>>>>>>>>>> which again, on its own would have fixed the original problem.
> :)
> >>>>>>>>>>>>
> >>>>>>>>>>>> Did you really intend to increase the real minimum stack from
> >> 128K
> >>>>>> to
> >>>>>>>>>>>> 256K ? (on a 64K page system)
> >>>>>>>>>>>>
> >>>>>>>>>>>> ---
> >>>>>>>>>>>>
> >>>>>>>>>>>> Focusing simply on the shared code change to adjust the
> requested
> >>>>>>>>>>>> stacksize by the amount of guard space (if any), this does not
> seem
> >>>>>>>>>>>> unreasonable. As you note it is restricted to non-JavaThreads
> and
> >>>>>> only
> >>>>>>>>>>>> adds a page to reserved stack space.
> >>>>>>>>>>>>
> >>>>>>>>>>>> My only query now is whether the minimum stacksize detection
> >> logic
> >>>>>>>>>>>> will correctly report the real minimum stack size (taking into
> >> account
> >>>>>>>>>>>> the need for the guard page) ?
> >>>>>>>>>>>>
> >>>>>>>>>>>> Thanks,
> >>>>>>>>>>>> David
> >>>>>>>>>>>>
> >>>>>>>>>>>>> So I really think this issue should be fixed.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Best regards,
> >>>>>>>>>>>>> Goetz.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>> -----Original Message-----
> >>>>>>>>>>>>>> From: David Holmes [mailto:david.holmes at oracle.com]
> >>>>>>>>>>>>>> Sent: Thursday, November 10, 2016 10:02 PM
> >>>>>>>>>>>>>> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>;
> hotspot-
> >>>>>>>>>>> runtime-
> >>>>>>>>>>>>>> dev at openjdk.java.net
> >>>>>>>>>>>>>> Subject: Re: RFR(M): 8169373: Work around linux NPTL stack
> >>>>>> guard
> >>>>>>>>> error.
> >>>>>>>>>>>>>> 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:
> >>>>>>>>>>>>>>>
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