The page_range_allocator attempts to merge neighbor page ranges when a page range is freed in order to minimize memory fragmentation.
However, the original implementation didn't validate indexes before checking the _bitset to determine whether a page range had a neighbor or not. This change make sure that indexes stay within bounds. This is the correct fix for the fix attempted in 44f8324e3f2e53f55022a1d93c8b072514e7ac07 Signed-off-by: Timmons C. Player <[email protected]> --- core/mempool.cc | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/core/mempool.cc b/core/mempool.cc index e0d0867..1ac3f67 100644 --- a/core/mempool.cc +++ b/core/mempool.cc @@ -761,13 +761,15 @@ page_range* page_range_allocator::alloc_aligned(size_t size, size_t offset, void page_range_allocator::free(page_range* pr) { - if (_bitmap[get_bitmap_idx(*pr) - 1]) { + auto idx = get_bitmap_idx(*pr); + if (idx && _bitmap[idx - 1]) { auto pr2 = *(reinterpret_cast<page_range**>(pr) - 1); remove(*pr2); pr2->size += pr->size; pr = pr2; } - if (_bitmap[get_bitmap_idx(*pr) + pr->size / page_size - 1]) { + auto next_idx = get_bitmap_idx(*pr) + pr->size / page_size; + if (next_idx < _bitmap.size() && _bitmap[next_idx]) { auto pr2 = static_cast<page_range*>(static_cast<void*>(pr) + pr->size); remove(*pr2); pr->size += pr2->size; -- 2.7.4 -- You received this message because you are subscribed to the Google Groups "OSv Development" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
