decommit unusable page(s) in medium heap blocks (bug 5822302) #985
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in medium heap blocks, if the object size is bigger than 1 page, it can cause the whole last 1~3 page(s) never been allocated. when such case is hit, decommit those pages to save memory as well as capture corruption. when returning the pages back to page allocator, we should commit those pages again for reuse, in case of OOM here, just decommit all pages in the heap block and let the page allocator to manage the decommitted pages. in rescan code, asserting that we never scan those unallocatable pages
it's hard to make the partial decommit withou refactoring page allocator, especially in background releasing pages, there will have race issues. changing to protect with NOACCESS for now. In the future after we implemented the capability of partially commit pages in pageAllocator we can change to use that, because that can save some memories.
…, do specialization on heapblock itself
chakrabot
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May 13, 2016
…2302) Merge pull request #985 from leirocks:mediumdecommit1 in medium heap blocks, if the object size is bigger than 1 page, it can cause the whole last 1~3 page(s) never been allocated. when such case is hit, decommit those pages to save memory as well as capture corruption. when returning the pages back to page allocator, we should commit those pages again for reuse, in case of OOM here, just decommit all pages in the heap block and let the page allocator to manage the decommitted pages. in rescan code, asserting that we never scan those unallocatable pages
This was referenced Aug 21, 2023
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in medium heap blocks, if the object size is bigger than 1 page, it can cause the whole last 1~3 page(s) never been allocated. when such case is hit, decommit those pages to save memory as well as capture corruption. when returning the pages back to page allocator, we should commit those pages again for reuse, in case of OOM here, just decommit all pages in the heap block and let the page allocator to manage the decommitted pages.
in rescan code, asserting that we never scan those unallocatable pages