diff mbox series

[1/3] mm: use nth_page() in place of direct struct page manipulation.

Message ID 20230830182753.55367-2-zi.yan@sent.com (mailing list archive)
State Superseded
Headers show
Series Use nth_page() in place of direct struct page manipulation | expand

Commit Message

Zi Yan Aug. 30, 2023, 6:27 p.m. UTC 
From: Zi Yan <ziy@nvidia.com>

When dealing with hugetlb pages, manipulating struct page pointers
directly can get to wrong struct page, since struct page is not guaranteed
to be contiguous on SPARSEMEM without VMEMMAP. Use nth_page() to handle
it properly.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 mm/cma.c            | 2 +-
 mm/hugetlb.c        | 2 +-
 mm/memory_hotplug.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

Comments

Muchun Song Aug. 31, 2023, 7:14 a.m. UTC | #1 
> On Aug 31, 2023, at 02:27, Zi Yan <zi.yan@sent.com> wrote:
> 
> From: Zi Yan <ziy@nvidia.com>
> 
> When dealing with hugetlb pages, manipulating struct page pointers
> directly can get to wrong struct page, since struct page is not guaranteed
> to be contiguous on SPARSEMEM without VMEMMAP. Use nth_page() to handle
> it properly.
> 
> Signed-off-by: Zi Yan <ziy@nvidia.com>

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

Maybe 3 separate patches would be better for backporting purpose.
Zi Yan Aug. 31, 2023, 3:37 p.m. UTC | #2 
On 31 Aug 2023, at 3:14, Muchun Song wrote:

>> On Aug 31, 2023, at 02:27, Zi Yan <zi.yan@sent.com> wrote:
>>
>> From: Zi Yan <ziy@nvidia.com>
>>
>> When dealing with hugetlb pages, manipulating struct page pointers
>> directly can get to wrong struct page, since struct page is not guaranteed
>> to be contiguous on SPARSEMEM without VMEMMAP. Use nth_page() to handle
>> it properly.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>
> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
>
> Maybe 3 separate patches would be better for backporting purpose.
Sure. Will split it and add Fixes in the next version.

--
Best Regards,
Yan, Zi
diff mbox series

Patch

diff --git a/mm/cma.c b/mm/cma.c
index da2967c6a223..2b2494fd6b59 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -505,7 +505,7 @@  struct page *cma_alloc(struct cma *cma, unsigned long count,
 	 */
 	if (page) {
 		for (i = 0; i < count; i++)
-			page_kasan_tag_reset(page + i);
+			page_kasan_tag_reset(nth_page(page, i));
 	}
 
 	if (ret && !no_warn) {
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ba6d39b71cb1..77e8d2cf4eed 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6474,7 +6474,7 @@  struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
 			}
 		}
 
-		page += ((address & ~huge_page_mask(h)) >> PAGE_SHIFT);
+		page = nth_page(page, ((address & ~huge_page_mask(h)) >> PAGE_SHIFT));
 
 		/*
 		 * Note that page may be a sub-page, and with vmemmap
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 1b03f4ec6fd2..3b301c4023ff 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1689,7 +1689,7 @@  static int scan_movable_pages(unsigned long start, unsigned long end,
 		 */
 		if (HPageMigratable(head))
 			goto found;
-		skip = compound_nr(head) - (page - head);
+		skip = compound_nr(head) - (pfn - page_to_pfn(head));
 		pfn += skip - 1;
 	}
 	return -ENOENT;