Commit 3c9fe8b8 authored by Miaohe Lin's avatar Miaohe Lin Committed by Andrew Morton
Browse files

mm/mremap: avoid unneeded do_munmap call 

When old_len == new_len, do_munmap will return -EINVAL due to len == 0. 
This errno will be simply ignored because of old_len != new_len check.  So
it is unnecessary to call do_munmap when old_len == new_len because
nothing is actually done.

Link: https://lkml.kernel.org/r/20220401081023.37080-1-linmiaohe@huawei.com


Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f4331956

mm/mremap.c

+2 −2
Original line number Diff line number Diff line
@@ -820,9 +820,9 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, 
			goto out;

	}



	if (old_len >= new_len) {

	if (old_len > new_len) {

		ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap);

		if (ret && old_len != new_len)

		if (ret)

			goto out;

		old_len = new_len;

	}