On 1/6/21 2:23 AM, Mike Kravetz wrote:
On 1/4/21 12:16 AM, Li Xinhai wrote:The current code would unnecessarily expand the address range. Consider one example, (start, end) = (1G-2M, 3G+2M), and (vm_start, vm_end) = (1G-4M, 3G+4M), the expected adjustment should be keep (1G-2M, 3G+2M) without expand. But the current result will be (1G-4M, 3G+4M). Actually, the range (1G-4M, 1G) and (3G, 3G+4M) would never been involved in pmd sharing. After this patch, we will check that the vma span at least one PUD aligned size and the start,end range overlap the aligned range of vma. With above example, the aligned vma range is (1G, 3G), so if (start, end) range is within (1G-4M, 1G), or within (3G, 3G+4M), then no adjustment to both start and end. Otherwise, we will have chance to adjust start downwards or end upwards without exceeding (vm_start, vm_end). Fixes: 75802ca66354 ("mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible") Suggested-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Peter Xu <peterx@xxxxxxxxxx> Signed-off-by: Li Xinhai <lixinhai.lxh@xxxxxxxxx> ---Thanks again. Comments and discussion in previous thread. Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Thanks for review.
