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8366495: Incorrect minimum memory size allocated in allocateNativeInternal() #27027

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8366495: Incorrect minimum memory size allocated in allocateNativeInternal() #27027

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8bbef84
update min size to Long.BYTES
offamitkumar Sep 1, 2025
18c67d5
update
offamitkumar Sep 2, 2025
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2 changes: 1 addition & 1 deletion src/java.base/share/classes/jdk/internal/foreign/SegmentFactories.java
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Original file line number Diff line number Diff line change
Expand Up @@ -198,7 +198,7 @@ private static long allocateNativeInternal(long byteSize, long byteAlignment, Me
}
// Always allocate at least some memory so that zero-length segments have distinct
// non-zero addresses.
alignedSize = Math.max(1, alignedSize);
alignedSize = Math.max(Long.BYTES, alignedSize);
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A few lines above this code there's a comment which says:

// Align the allocation size up to a multiple of 8 so we can init the memory with longs
long alignedSize = init ? Utils.alignUp(byteSize, Long.BYTES) : byteSize;

Should we have a similar comment as well as a check for init here? After all, we are increasing this size here because of init initializing the allocated memory. So perhaps something like:

// Always allocate at least some memory so that zero-length segments have distinct
// non-zero addresses. If we are initializing the allocated memory, then use a minimum
// size of 8 because we init the memory with longs.
alignedSize = Math.max((init ? Long.BYTES : 1), alignedSize);

If you do use this newer proposed change, then please have it verified against the original reproducer.


long allocationSize;
long allocationBase;
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