From: Kirill A. Shutemov <kirill@shutemov.name>
Date: Fri, 16 Oct 2020 03:05:36 +0000 (-0700)
Subject: mm/huge_memory: fix split assumption of page size
X-Git-Tag: v5.10-rc1~106^2~133
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8cce54756806e5777069c46011c5f54f9feac717;p=thirdparty%2Flinux.git

mm/huge_memory: fix split assumption of page size

File THPs may now be of arbitrary size, and we can't rely on that size
after doing the split so remember the number of pages before we start the
split.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: SeongJae Park <sjpark@amazon.de>
Cc: Huang Ying <ying.huang@intel.com>
Link: https://lkml.kernel.org/r/20200908195539.25896-6-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b63c98516a7cc..5934ef722e284 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2335,13 +2335,13 @@ static void unmap_page(struct page *page)
 	VM_BUG_ON_PAGE(!unmap_success, page);
 }
 
-static void remap_page(struct page *page)
+static void remap_page(struct page *page, unsigned int nr)
 {
 	int i;
 	if (PageTransHuge(page)) {
 		remove_migration_ptes(page, page, true);
 	} else {
-		for (i = 0; i < HPAGE_PMD_NR; i++)
+		for (i = 0; i < nr; i++)
 			remove_migration_ptes(page + i, page + i, true);
 	}
 }
@@ -2419,6 +2419,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 	struct lruvec *lruvec;
 	struct address_space *swap_cache = NULL;
 	unsigned long offset = 0;
+	unsigned int nr = thp_nr_pages(head);
 	int i;
 
 	lruvec = mem_cgroup_page_lruvec(head, pgdat);
@@ -2434,7 +2435,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 		xa_lock(&swap_cache->i_pages);
 	}
 
-	for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
+	for (i = nr - 1; i >= 1; i--) {
 		__split_huge_page_tail(head, i, lruvec, list);
 		/* Some pages can be beyond i_size: drop them from page cache */
 		if (head[i].index >= end) {
@@ -2454,7 +2455,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 
 	ClearPageCompound(head);
 
-	split_page_owner(head, HPAGE_PMD_NR);
+	split_page_owner(head, nr);
 
 	/* See comment in __split_huge_page_tail() */
 	if (PageAnon(head)) {
@@ -2473,9 +2474,9 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 
 	spin_unlock_irqrestore(&pgdat->lru_lock, flags);
 
-	remap_page(head);
+	remap_page(head, nr);
 
-	for (i = 0; i < HPAGE_PMD_NR; i++) {
+	for (i = 0; i < nr; i++) {
 		struct page *subpage = head + i;
 		if (subpage == page)
 			continue;
@@ -2729,7 +2730,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 fail:		if (mapping)
 			xa_unlock(&mapping->i_pages);
 		spin_unlock_irqrestore(&pgdata->lru_lock, flags);
-		remap_page(head);
+		remap_page(head, thp_nr_pages(head));
 		ret = -EBUSY;
 	}