Function mi_find_page

3rd/mimalloc-2.0.9/src/page.c:858–869

Allocate a page Note: in debug mode the size includes MI_PADDING_SIZE and might have overflowed.

// Allocate a page
// Note: in debug mode the size includes MI_PADDING_SIZE and might have overflowed.
static mi_page_t* mi_find_page(mi_heap_t* heap, size_t size, size_t huge_alignment) mi_attr_noexcept {
  // huge allocation?
  const size_t req_size = size - MI_PADDING_SIZE;  // correct for padding_size in case of an overflow on `size`  
  if mi_unlikely(req_size > (MI_MEDIUM_OBJ_SIZE_MAX - MI_PADDING_SIZE) || huge_alignment > 0) {
    if mi_unlikely(req_size > PTRDIFF_MAX) {  // we don't allocate more than PTRDIFF_MAX (see <https://sourceware.org/ml/libc-announce/2019/msg00001.html>)
      _mi_error_message(EOVERFLOW, "allocation request is too large (%zu bytes)\n", req_size);
      return NULL;
    }
    else {
      return mi_large_huge_page_alloc(heap,size,huge_alignment);
    }
  }
  else {
    // otherwise find a page with free blocks in our size segregated queues
    mi_assert_internal(size >= MI_PADDING_SIZE);