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Stephen Warren authored
Commit 4f144a41 "malloc: work around some memalign fragmentation issues" enhanced memalign() so that it can succeed in more cases where heap fragmentation is present. However, it did not solve as many cases as it could. This patch enhances the code to cover more cases. The alignment code works by allocating more space than the user requests, then adjusting the returned pointer to achieve alignment. In general, one must allocate "alignment" bytes more than the user requested in order to guarantee that alignment is possible. This is what the original code does. The previous enhancement attempted a second allocation if the padded allocation failed, and succeeded if that allocation just happened to be aligned; a fluke that happened often in practice. There are still cases where this could fail, yet where it is still possible to honor the user's allocation request. In particular, if the heap contains a free region that is large enough for the user's request, and ...
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