[PATCH 4.14 22/30] mm: hugetlbfs: fix cannot migrate the fallocated HugeTLB page

Greg Kroah-Hartman
2021-02-08T15:59:05Z

From: Muchun Song <songmuchun@bytedance.com>

commit 585fc0d2871c9318c949fbf45b1f081edd489e96 upstream.

If a new hugetlb page is allocated during fallocate it will not be
marked as active (set_page_huge_active) which will result in a later
isolate_huge_page failure when the page migration code would like to
move that page. Such a failure would be unexpected and wrong.

Only export set_page_huge_active, just leave clear_page_huge_active as
static. Because there are no external users.

Link: https://lkml.kernel.org/r/20210115124942.46403-3-songmuchun@bytedance.com
Fixes: 70c3547e36f5 (hugetlbfs: add hugetlbfs_fallocate())
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yang Shi <shy828301@gmail.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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/hugetlbfs/inode.c | 3 ++-
include/linux/hugetlb.h | 3 +++
mm/hugetlb.c | 2 +-
3 files changed, 6 insertions(+), 2 deletions(-)

--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -649,8 +649,9 @@ static long hugetlbfs_fallocate(struct f

mutex_unlock(&hugetlb_fault_mutex_table[hash]);

+ set_page_huge_active(page);
/*
- * page_put due to reference from alloc_huge_page()
+ * put_page() due to reference from alloc_huge_page()
* unlock_page because locked by add_to_page_cache()
*/
put_page(page);
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -531,6 +531,9 @@ static inline void set_huge_swap_pte_at(
set_huge_pte_at(mm, addr, ptep, pte);
}
#endif
+
+void set_page_huge_active(struct page *page);
+
#else /* CONFIG_HUGETLB_PAGE */
struct hstate {};
#define alloc_huge_page(v, a, r) NULL
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1238,7 +1238,7 @@ bool page_huge_active(struct page *page)
}

/* never called for tail page */
-static void set_page_huge_active(struct page *page)
+void set_page_huge_active(struct page *page)
{
VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
SetPagePrivate(&page[1]);