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Zhang Boyang
2282cbfe5a
When grub_memalign() encounters out-of-memory, it will try grub_mm_add_region_fn() to request more memory from system firmware. However, the size passed to it doesn't take region management overhead into account. Adding a memory area of "size" bytes may result in a heap region of less than "size" bytes really available. Thus, the new region may not be adequate for current allocation request, confusing out-of-memory handling code. This patch introduces GRUB_MM_MGMT_OVERHEAD to address the region management overhead (e.g. metadata, padding). The value of this new constant must be large enough to make sure grub_memalign(align, size) always succeeds after a successful call to grub_mm_init_region(addr, size + align + GRUB_MM_MGMT_OVERHEAD), for any given addr and size (assuming no integer overflow). The size passed to grub_mm_add_region_fn() is now correctly adjusted, thus if grub_mm_add_region_fn() succeeded, current allocation request can always succeed. Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>