[llvm-bugs] [Bug 27649] New: PowerPC Segfault within KMPC Runtime when managing a large set of tasks

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=27649

            Bug ID: 27649
           Summary: PowerPC Segfault within KMPC Runtime when managing a
                    large set of tasks
           Product: OpenMP
           Version: unspecified
          Hardware: Other
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Runtime Library
          Assignee: unassignedbugs at nondot.org
          Reporter: matt.davis at pgroup.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 16311
  --> https://llvm.org/bugs/attachment.cgi?id=16311&action=edit
Segfaulting test case

This looks to be a bug when using a large number of tasks (800000).  The
segfault seems to manifest with task allocation/reclaim, I get segfaults in
both ___kmp_fast_free and ___kmp_fast_allocate (clang 3.8). 


Program received signal SIGSEGV, Segmentation fault.
0x00003fffb7ef9790 in ___kmp_fast_allocate () from
/llvm/linuxpower/3.8-openmp/lib/libomp.so
(gdb) bt
#0  0x00003fffb7ef9790 in ___kmp_fast_allocate () from
/llvm/linuxpower/3.8-openmp/lib/libomp.so
#1  0x00003fffb7f26b54 in __kmp_task_alloc () from
/llvm/linuxpower/3.8-openmp/lib/libomp.so
#2  0x00003fffb7f26f18 in __kmpc_omp_task_alloc () from
/llvm/linuxpower/3.8-openmp/lib/libomp.so
#3  0x0000000010000bf4 in .omp_outlined. ()
#4  0x00003fffb7f3293c in __kmp_invoke_microtask () from
/llvm/linuxpower/3.8-openmp/lib/libomp.so
#5  0x00003fffb7f121ec in __kmp_invoke_task_func () from
/llvm/linuxpower/3.8-openmp/lib/libomp.so
#6  0x00003fffb7f131e4 in __kmp_fork_call () from
/llvm/linuxpower/3.8-openmp/lib/libomp.so
#7  0x00003fffb7f029f4 in __kmpc_fork_call () from
/llvm/linuxpower/3.8-openmp/lib/libomp.so
#8  0x0000000010000b00 in main ()


If I define USE_FAST_MEM=0 in a different KMPC library (code from svn
repository 268538 (May 4, 2016), I will still get a segfault: 
Program received signal SIGSEGV, Segmentation fault.
0x00003fffb7f02a28 in brel(kmp_info*, void*) () from kmpc/runtime/src/libomp.so
Program received signal SIGSEGV, Segmentation fault.
0x00003fffb7ef7a80 in bget(kmp_info*, long) () from
openmp/runtime/src/libomp.so
(gdb) bt
#0  0x00003fffb7ef7a80 in bget(kmp_info*, long) () from
openmp/runtime/src/libomp.so
#1  0x00003fffb7f26054 in __kmp_task_alloc () from openmp/runtime/src/libomp.so
#2  0x00003fffb7f26418 in __kmpc_omp_task_alloc () from
openmp/runtime/src/libomp.so
#3  0x0000000010000ac4 in .omp_outlined. ()
#4  0x00003fffb7f31e5c in __kmp_invoke_microtask () from
openmp/runtime/src/libomp.so
#5  0x00003fffb7f10ebc in __kmp_invoke_task_func () from
openmp/runtime/src/libomp.so
#6  0x00003fffb7f11eb4 in __kmp_fork_call () from openmp/runtime/src/libomp.so
#7  0x00003fffb7f01cd4 in __kmpc_fork_call () from openmp/runtime/src/libomp.so
#8  0x00000000100009d0 in main ()

Built using:
clang -fopenmp try2.c

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