diff mbox series

mm: page_isolation: use compound_nr() correctly in isolate_single_pageblock()

Message ID 20220531024450.2498431-1-zi.yan@sent.com (mailing list archive)
State New
Headers show
Series mm: page_isolation: use compound_nr() correctly in isolate_single_pageblock() | expand

Commit Message

Zi Yan May 31, 2022, 2:44 a.m. UTC
From: Zi Yan <ziy@nvidia.com>

When compound_nr(page) was used, page was not guaranteed to be the head
of the compound page and it could cause an infinite loop. Fix it by calling
it on the head page.

Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity")
Reported-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/linux-mm/20220530115027.123341-1-anshuman.khandual@arm.com/
Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 mm/page_isolation.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Anshuman Khandual May 31, 2022, 3:12 a.m. UTC | #1
On 5/31/22 08:14, Zi Yan wrote:
> From: Zi Yan <ziy@nvidia.com>
> 
> When compound_nr(page) was used, page was not guaranteed to be the head
> of the compound page and it could cause an infinite loop. Fix it by calling
> it on the head page.
> 
> Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity")
> Reported-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Link: https://lore.kernel.org/linux-mm/20220530115027.123341-1-anshuman.khandual@arm.com/
> Signed-off-by: Zi Yan <ziy@nvidia.com>

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

> ---
>  mm/page_isolation.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
> index 6021f8444b5a..d200d41ad0d3 100644
> --- a/mm/page_isolation.c
> +++ b/mm/page_isolation.c
> @@ -385,9 +385,9 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
>  		 * above do the rest. If migration is not possible, just fail.
>  		 */
>  		if (PageCompound(page)) {
> -			unsigned long nr_pages = compound_nr(page);
>  			struct page *head = compound_head(page);
>  			unsigned long head_pfn = page_to_pfn(head);
> +			unsigned long nr_pages = compound_nr(head);
>  
>  			if (head_pfn + nr_pages <= boundary_pfn) {
>  				pfn = head_pfn + nr_pages;
Muchun Song May 31, 2022, 5:40 a.m. UTC | #2
On Mon, May 30, 2022 at 10:44:50PM -0400, Zi Yan wrote:
> From: Zi Yan <ziy@nvidia.com>
> 
> When compound_nr(page) was used, page was not guaranteed to be the head
> of the compound page and it could cause an infinite loop. Fix it by calling
> it on the head page.
> 
> Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity")
> Reported-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Link: https://lore.kernel.org/linux-mm/20220530115027.123341-1-anshuman.khandual@arm.com/
> Signed-off-by: Zi Yan <ziy@nvidia.com>

Acked-by: Muchun Song <songmuchun@bytedance.com>

Thanks.
Oscar Salvador May 31, 2022, 8:56 a.m. UTC | #3
On Mon, May 30, 2022 at 10:44:50PM -0400, Zi Yan wrote:
> From: Zi Yan <ziy@nvidia.com>
> 
> When compound_nr(page) was used, page was not guaranteed to be the head
> of the compound page and it could cause an infinite loop. Fix it by calling
> it on the head page.
> 
> Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity")
> Reported-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Link: https://lore.kernel.org/linux-mm/20220530115027.123341-1-anshuman.khandual@arm.com/
> Signed-off-by: Zi Yan <ziy@nvidia.com>

Reviewed-by: Oscar Salvador <osalvador@suse.de>

> ---
>  mm/page_isolation.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
> index 6021f8444b5a..d200d41ad0d3 100644
> --- a/mm/page_isolation.c
> +++ b/mm/page_isolation.c
> @@ -385,9 +385,9 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
>  		 * above do the rest. If migration is not possible, just fail.
>  		 */
>  		if (PageCompound(page)) {
> -			unsigned long nr_pages = compound_nr(page);
>  			struct page *head = compound_head(page);
>  			unsigned long head_pfn = page_to_pfn(head);
> +			unsigned long nr_pages = compound_nr(head);
>  
>  			if (head_pfn + nr_pages <= boundary_pfn) {
>  				pfn = head_pfn + nr_pages;
> -- 
> 2.35.1
>
Miaohe Lin May 31, 2022, 9:05 a.m. UTC | #4
On 2022/5/31 10:44, Zi Yan wrote:
> From: Zi Yan <ziy@nvidia.com>
> 
> When compound_nr(page) was used, page was not guaranteed to be the head
> of the compound page and it could cause an infinite loop. Fix it by calling
> it on the head page.
> 
> Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity")
> Reported-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Link: https://lore.kernel.org/linux-mm/20220530115027.123341-1-anshuman.khandual@arm.com/
> Signed-off-by: Zi Yan <ziy@nvidia.com>

LGTM. Thanks!

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

> ---
>  mm/page_isolation.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
> index 6021f8444b5a..d200d41ad0d3 100644
> --- a/mm/page_isolation.c
> +++ b/mm/page_isolation.c
> @@ -385,9 +385,9 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
>  		 * above do the rest. If migration is not possible, just fail.
>  		 */
>  		if (PageCompound(page)) {
> -			unsigned long nr_pages = compound_nr(page);
>  			struct page *head = compound_head(page);
>  			unsigned long head_pfn = page_to_pfn(head);
> +			unsigned long nr_pages = compound_nr(head);
>  
>  			if (head_pfn + nr_pages <= boundary_pfn) {
>  				pfn = head_pfn + nr_pages;
>
diff mbox series

Patch

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 6021f8444b5a..d200d41ad0d3 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -385,9 +385,9 @@  static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
 		 * above do the rest. If migration is not possible, just fail.
 		 */
 		if (PageCompound(page)) {
-			unsigned long nr_pages = compound_nr(page);
 			struct page *head = compound_head(page);
 			unsigned long head_pfn = page_to_pfn(head);
+			unsigned long nr_pages = compound_nr(head);
 
 			if (head_pfn + nr_pages <= boundary_pfn) {
 				pfn = head_pfn + nr_pages;