Hi Dan,
On 1/6/2022 5:12 PM, Dan Carpenter wrote:
Hello Baolin Wang,
The patch 86522923bb29: "mm/damon: add access checking for hugetlb
pages" from Dec 30, 2021, leads to the following Smatch static
checker warning:
mm/damon/vaddr.c:405 damon_hugetlb_mkold()
warn: 'page' can't be NULL.
mm/damon/vaddr.c
398 static void damon_hugetlb_mkold(pte_t *pte, struct mm_struct *mm,
399 struct vm_area_struct *vma, unsigned long addr)
400 {
401 bool referenced = false;
402 pte_t entry = huge_ptep_get(pte);
403 struct page *page = pte_page(entry);
404
--> 405 if (!page)
I don't think it makes sense to check "page" because we're already dead
if pte_page() starts returning NULL. Maybe check "entry"?
Thanks for reporting. Yes, no need to check the 'page' returned from
pte_page(), and the entry already be checked before to make sure it is a
valid and present entry. Thus I will send a fix patch to remove the
redundant page checking. Thanks.
