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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - tsan: false positives on shmat"
href="https://bugs.llvm.org/show_bug.cgi?id=40282">40282</a>
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<th>Summary</th>
<td>tsan: false positives on shmat
</td>
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<th>Product</th>
<td>compiler-rt
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>tsan
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>dvyukov@google.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>Reported internally, don't have a public repro.
The crux: shmat/shmdt allocate/deallocate memory (like mmap/munmap). We don't
do anything in shmat/shmdt interceptors, so if the memory becomes reused across
shmat calls in different threads, tsan may report a false positive. Accesses to
the new mapping of the memory "race" with accesses to the old mapping at the
same address.
We need shmat/shmdt interceptors to do the same as mmap/munmap interceptors.
Probably the common code to "map" and "unmap" a range can be factored out.</pre>
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