[PATCH v2] mm/damon: Remove redundant page validation

[PATCH v2] mm/damon: Remove redundant page validation

[Baolin Wang]

It will never get a NULL page by pte_page() as discussed in thread [1],
thus remove the redundant page validation to fix below Smatch static
checker warning.

    mm/damon/vaddr.c:405 damon_hugetlb_mkold()
    warn: 'page' can't be NULL.

[1] https://lore.kernel.org/linux-mm/20220106091200.GA14564@kili/

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
---
Changes from v1:
 - Improve the commit message suggested by SeongJae.
 - Add reviewed-by tag from SeongJae.
---
 mm/damon/vaddr.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index 89b6468d..8a52e00 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -402,9 +402,6 @@ static void damon_hugetlb_mkold(pte_t *pte, struct mm_struct *mm,
 	pte_t entry = huge_ptep_get(pte);
 	struct page *page = pte_page(entry);
 
-	if (!page)
-		return;
-
 	get_page(page);
 
 	if (pte_young(entry)) {
@@ -564,9 +561,6 @@ static int damon_young_hugetlb_entry(pte_t *pte, unsigned long hmask,
 		goto out;
 
 	page = pte_page(entry);
-	if (!page)
-		goto out;
-
 	get_page(page);
 
 	if (pte_young(entry) || !page_is_idle(page) ||
-- 
1.8.3.1

Re: [PATCH v2] mm/damon: Remove redundant page validation

[David Rientjes]

On Mon, 17 Jan 2022, Baolin Wang wrote:

> It will never get a NULL page by pte_page() as discussed in thread [1],
> thus remove the redundant page validation to fix below Smatch static
> checker warning.
> 
>     mm/damon/vaddr.c:405 damon_hugetlb_mkold()
>     warn: 'page' can't be NULL.
> 
> [1] https://lore.kernel.org/linux-mm/20220106091200.GA14564@kili/
> 
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Reviewed-by: SeongJae Park <sj@kernel.org>

Acked-by: David Rientjes <rientjes@google.com>

Re: [PATCH v2] mm/damon: Remove redundant page validation

[Souptick Joarder]

On Mon, Jan 24, 2022 at 11:50 PM David Rientjes <rientjes@google.com> wrote:
>
> On Mon, 17 Jan 2022, Baolin Wang wrote:
>
> > It will never get a NULL page by pte_page() as discussed in thread [1],
> > thus remove the redundant page validation to fix below Smatch static
> > checker warning.
> >
> >     mm/damon/vaddr.c:405 damon_hugetlb_mkold()
> >     warn: 'page' can't be NULL.
> >
> > [1] https://lore.kernel.org/linux-mm/20220106091200.GA14564@kili/
> >
> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> > Reviewed-by: SeongJae Park <sj@kernel.org>
>
> Acked-by: David Rientjes <rientjes@google.com>

Acked-by: Souptick Joarder <jrdr.linux@gmail.com>

>

Re: [PATCH v2] mm/damon: Remove redundant page validation

[Miaohe Lin]

On 2022/1/17 10:34, Baolin Wang wrote:
> It will never get a NULL page by pte_page() as discussed in thread [1],
> thus remove the redundant page validation to fix below Smatch static
> checker warning.
> 
>     mm/damon/vaddr.c:405 damon_hugetlb_mkold()
>     warn: 'page' can't be NULL.
> 
> [1] https://lore.kernel.org/linux-mm/20220106091200.GA14564@kili/
> 
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Reviewed-by: SeongJae Park <sj@kernel.org>

LGTM. Thanks.

Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

> ---
> Changes from v1:
>  - Improve the commit message suggested by SeongJae.
>  - Add reviewed-by tag from SeongJae.
> ---
>  mm/damon/vaddr.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
> index 89b6468d..8a52e00 100644
> --- a/mm/damon/vaddr.c
> +++ b/mm/damon/vaddr.c
> @@ -402,9 +402,6 @@ static void damon_hugetlb_mkold(pte_t *pte, struct mm_struct *mm,
>  	pte_t entry = huge_ptep_get(pte);
>  	struct page *page = pte_page(entry);
>  
> -	if (!page)
> -		return;
> -
>  	get_page(page);
>  
>  	if (pte_young(entry)) {
> @@ -564,9 +561,6 @@ static int damon_young_hugetlb_entry(pte_t *pte, unsigned long hmask,
>  		goto out;
>  
>  	page = pte_page(entry);
> -	if (!page)
> -		goto out;
> -
>  	get_page(page);
>  
>  	if (pte_young(entry) || !page_is_idle(page) ||
>