linux-kernel - [PATCH v4 3/8] mm/hugetlb: Add page_mask for hugetlb_follow_page

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Date:   Wed, 28 Jun 2023 17:53:05 -0400
From:   Peter Xu <peterx@...hat.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     David Hildenbrand <david@...hat.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Mike Rapoport <rppt@...nel.org>,
        John Hubbard <jhubbard@...dia.com>,
        Matthew Wilcox <willy@...radead.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Yang Shi <shy828301@...il.com>,
        James Houghton <jthoughton@...gle.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Hugh Dickins <hughd@...gle.com>, peterx@...hat.com
Subject: [PATCH v4 3/8] mm/hugetlb: Add page_mask for hugetlb_follow_page_mask()

follow_page() doesn't need it, but we'll start to need it when unifying gup
for hugetlb.

Reviewed-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 include/linux/hugetlb.h | 8 +++++---
 mm/gup.c                | 3 ++-
 mm/hugetlb.c            | 5 ++++-
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index ca3c8e10f24a..9f282f370d96 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -131,7 +131,8 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
 int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *,
 			    struct vm_area_struct *, struct vm_area_struct *);
 struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
-				unsigned long address, unsigned int flags);
+				      unsigned long address, unsigned int flags,
+				      unsigned int *page_mask);
 long follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *,
 			 struct page **, unsigned long *, unsigned long *,
 			 long, unsigned int, int *);
@@ -297,8 +298,9 @@ static inline void adjust_range_if_pmd_sharing_possible(
 {
 }
 
-static inline struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
-				unsigned long address, unsigned int flags)
+static inline struct page *hugetlb_follow_page_mask(
+    struct vm_area_struct *vma, unsigned long address, unsigned int flags,
+    unsigned int *page_mask)
 {
 	BUILD_BUG(); /* should never be compiled in if !CONFIG_HUGETLB_PAGE*/
 }
diff --git a/mm/gup.c b/mm/gup.c
index 06bc2e31f209..1e2e23084f3c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -780,7 +780,8 @@ static struct page *follow_page_mask(struct vm_area_struct *vma,
 	 * Ordinary GUP uses follow_hugetlb_page for hugetlb processing.
 	 */
 	if (is_vm_hugetlb_page(vma))
-		return hugetlb_follow_page_mask(vma, address, flags);
+		return hugetlb_follow_page_mask(vma, address, flags,
+						&ctx->page_mask);
 
 	pgd = pgd_offset(mm, address);
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4410139cf890..15e82a8a2b76 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6454,7 +6454,8 @@ static inline bool __follow_hugetlb_must_fault(struct vm_area_struct *vma,
 }
 
 struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
-				unsigned long address, unsigned int flags)
+				      unsigned long address, unsigned int flags,
+				      unsigned int *page_mask)
 {
 	struct hstate *h = hstate_vma(vma);
 	struct mm_struct *mm = vma->vm_mm;
@@ -6504,6 +6505,8 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
 			page = ERR_PTR(ret);
 			goto out;
 		}
+
+		*page_mask = (1U << huge_page_order(h)) - 1;
 	}
 out:
 	spin_unlock(ptl);
-- 
2.41.0