resizeLarge

        fn resizeLarge(
            self: *Self,
            old_mem: []u8,
            alignment: mem.Alignment,
            new_size: usize,
            ret_addr: usize,
            may_move: bool,
        ) ?[*]u8 {
            if (config.retain_metadata and may_move) {
                // Before looking up the entry (since this could invalidate
                // it), we must reserve space for the new entry in case the
                // allocation is relocated.
                self.large_allocations.ensureUnusedCapacity(self.backing_allocator, 1) catch return null;
            }

            const entry = self.large_allocations.getEntry(@intFromPtr(old_mem.ptr)) orelse {
                if (config.safety) {
                    @panic("Invalid free");
                } else {
                    unreachable;
                }
            };

            if (config.retain_metadata and entry.value_ptr.freed) {
                if (config.safety) {
                    reportDoubleFree(ret_addr, entry.value_ptr.getStackTrace(.alloc), entry.value_ptr.getStackTrace(.free));
                    @panic("Unrecoverable double free");
                } else {
                    unreachable;
                }
            }

            if (config.safety and old_mem.len != entry.value_ptr.bytes.len) {
                @branchHint(.cold);
                var addr_buf: [stack_n]usize = undefined;
                const free_stack_trace = std.debug.captureCurrentStackTrace(.{ .first_address = ret_addr }, &addr_buf);
                log.err("Allocation size {d} bytes does not match free size {d}. Allocation: {f} Free: {f}", .{
                    entry.value_ptr.bytes.len,
                    old_mem.len,
                    std.debug.FormatStackTrace{
                        .stack_trace = entry.value_ptr.getStackTrace(.alloc),
                        .terminal_mode = std.log.terminalMode(),
                    },
                    std.debug.FormatStackTrace{
                        .stack_trace = free_stack_trace,
                        .terminal_mode = std.log.terminalMode(),
                    },
                });
            }

            // If this would move the allocation into a small size class,
            // refuse the request, because it would require creating small
            // allocation metadata.
            const new_size_class_index: usize = @max(@bitSizeOf(usize) - @clz(new_size - 1), @backingInt(alignment));
            if (new_size_class_index < self.buckets.len) return null;

            // Do memory limit accounting with requested sizes rather than what
            // backing_allocator returns because if we want to return
            // error.OutOfMemory, we have to leave allocation untouched, and
            // that is impossible to guarantee after calling
            // backing_allocator.rawResize.
            const prev_req_bytes = self.total_requested_bytes;
            if (config.enable_memory_limit) {
                const new_req_bytes = prev_req_bytes + new_size - entry.value_ptr.requested_size;
                if (new_req_bytes > prev_req_bytes and new_req_bytes > self.requested_memory_limit) {
                    return null;
                }
                self.total_requested_bytes = new_req_bytes;
            }

            const opt_resized_ptr = if (may_move)
                self.backing_allocator.rawRemap(old_mem, alignment, new_size, ret_addr)
            else if (self.backing_allocator.rawResize(old_mem, alignment, new_size, ret_addr))
                old_mem.ptr
            else
                null;

            const resized_ptr = opt_resized_ptr orelse {
                if (config.enable_memory_limit) {
                    self.total_requested_bytes = prev_req_bytes;
                }
                return null;
            };

            if (config.enable_memory_limit) {
                entry.value_ptr.requested_size = new_size;
            }

            if (config.verbose_log) {
                log.info("large resize {d} bytes at {*} to {d} at {*}", .{
                    old_mem.len, old_mem.ptr, new_size, resized_ptr,
                });
            }
            entry.value_ptr.bytes = resized_ptr[0..new_size];
            if (config.resize_stack_traces)
                entry.value_ptr.captureStackTrace(ret_addr, .alloc);

            // Update the key of the hash map if the memory was relocated.
            if (resized_ptr != old_mem.ptr) {
                const large_alloc = entry.value_ptr.*;
                if (config.retain_metadata) {
                    entry.value_ptr.freed = true;
                    entry.value_ptr.captureStackTrace(ret_addr, .free);
                } else {
                    self.large_allocations.removeByPtr(entry.key_ptr);
                }

                const gop = self.large_allocations.getOrPutAssumeCapacity(@intFromPtr(resized_ptr));
                if (config.retain_metadata and !config.never_unmap) {
                    // Backing allocator may be reusing memory that we're retaining metadata for
                    assert(!gop.found_existing or gop.value_ptr.freed);
                } else {
                    assert(!gop.found_existing); // This would mean the kernel double-mapped pages.
                }
                gop.value_ptr.* = large_alloc;
            }

            return resized_ptr;
        }