<html>
<head>
<base href="https://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - PowerPC Segfault within KMPC Runtime when managing a large set of tasks"
href="https://llvm.org/bugs/show_bug.cgi?id=27649">27649</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>PowerPC Segfault within KMPC Runtime when managing a large set of tasks
</td>
</tr>
<tr>
<th>Product</th>
<td>OpenMP
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Runtime Library
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>matt.davis@pgroup.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16311" name="attach_16311" title="Segfaulting test case">attachment 16311</a> <a href="attachment.cgi?id=16311&action=edit" title="Segfaulting test case">[details]</a></span>
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</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>