[PATCH 4.19 12/34] mm: page_vma_mapped_walk(): settle PageHuge on entry

Greg Kroah-Hartman
2021-07-09T13:21:57Z

From: Hugh Dickins <hughd@google.com>

[ Upstream commit 6d0fd5987657cb0c9756ce684e3a74c0f6351728 ]

page_vma_mapped_walk() cleanup: get the hugetlbfs PageHuge case out of
the way at the start, so no need to worry about it later.

Link: https://lkml.kernel.org/r/e31a483c-6d73-a6bb-26c5-43c3b880a2@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Wang Yugui <wangyugui@e16-tech.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/page_vma_mapped.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index d146f6d31a62..036ce20bb154 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -148,10 +148,11 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
if (pvmw->pmd && !pvmw->pte)
return not_found(pvmw);

- if (pvmw->pte)
- goto next_pte;
-
if (unlikely(PageHuge(page))) {
+ /* The only possible mapping was handled on last iteration */
+ if (pvmw->pte)
+ return not_found(pvmw);
+
/* when pud is not present, pte will be NULL */
pvmw->pte = huge_pte_offset(mm, pvmw->address,
PAGE_SIZE << compound_order(page));
@@ -164,6 +165,9 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
return not_found(pvmw);
return true;
}
+
+ if (pvmw->pte)
+ goto next_pte;
restart:
pgd = pgd_offset(mm, pvmw->address);
if (!pgd_present(*pgd))
@@ -229,7 +233,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
return true;
next_pte:
/* Seek to next pte only makes sense for THP */
- if (!PageTransHuge(page) || PageHuge(page))
+ if (!PageTransHuge(page))
return not_found(pvmw);
end = vma_address_end(page, pvmw->vma);
do {
--
2.30.2