tree e6c46e8b9640e07449701ddfd9f9c13a15c6f188
parent bf3d12b9f7f9e7c4ae4aa94c6c81400d3bf688e6
author Miaohe Lin <linmiaohe@huawei.com> 1620178475 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1620239241 -0700

mm/hugeltb: clarify (chg - freed) won't go negative in hugetlb_unreserve_pages()

The resv_map could be NULL since this routine can be called in the evict
inode path for all hugetlbfs inodes and we will have chg = 0 in this case.
But (chg - freed) won't go negative as Mike pointed out:

 "If resv_map is NULL, then no hugetlb pages can be allocated/associated
  with the file.  As a result, remove_inode_hugepages will never find any
  huge pages associated with the inode and the passed value 'freed' will
  always be zero."

Add a comment clarifying this to make it clear and also avoid confusion.

Link: https://lkml.kernel.org/r/20210410072348.20437-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Feilong Lin <linfeilong@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>