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From:   Matthew Wilcox <willy@infradead.org>
To:     linux-fsdevel@vger.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH v6 39/51] mm: Remove assumptions of THP size
Date:   Wed, 10 Jun 2020 13:13:33 -0700
Message-Id: <20200610201345.13273-40-willy@infradead.org>
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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Remove direct uses of HPAGE_PMD_NR in paths that aren't necessarily
PMD sized.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/huge_memory.c | 15 ++++++++-------
 mm/rmap.c        | 10 +++++-----
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 744863aa0374..c25d8e2310e8 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2340,7 +2340,7 @@ static void remap_page(struct page *page)
 	if (PageTransHuge(page)) {
 		remove_migration_ptes(page, page, true);
 	} else {
-		for (i = 0; i < HPAGE_PMD_NR; i++)
+		for (i = 0; i < thp_nr_pages(page); i++)
 			remove_migration_ptes(page + i, page + i, true);
 	}
 }
@@ -2415,6 +2415,7 @@ 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);
@@ -2430,7 +2431,7 @@ 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) {
@@ -2471,7 +2472,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 
 	remap_page(head);
 
-	for (i = 0; i < HPAGE_PMD_NR; i++) {
+	for (i = 0; i < nr; i++) {
 		struct page *subpage = head + i;
 		if (subpage == page)
 			continue;
@@ -2553,14 +2554,14 @@ int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
 	page = compound_head(page);
 
 	_total_mapcount = ret = 0;
-	for (i = 0; i < HPAGE_PMD_NR; i++) {
+	for (i = 0; i < thp_nr_pages(page); i++) {
 		mapcount = atomic_read(&page[i]._mapcount) + 1;
 		ret = max(ret, mapcount);
 		_total_mapcount += mapcount;
 	}
 	if (PageDoubleMap(page)) {
 		ret -= 1;
-		_total_mapcount -= HPAGE_PMD_NR;
+		_total_mapcount -= thp_nr_pages(page);
 	}
 	mapcount = compound_mapcount(page);
 	ret += mapcount;
@@ -2577,9 +2578,9 @@ bool can_split_huge_page(struct page *page, int *pextra_pins)
 
 	/* Additional pins from page cache */
 	if (PageAnon(page))
-		extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
+		extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0;
 	else
-		extra_pins = HPAGE_PMD_NR;
+		extra_pins = thp_nr_pages(page);
 	if (pextra_pins)
 		*pextra_pins = extra_pins;
 	return total_mapcount(page) == page_count(page) - extra_pins - 1;
diff --git a/mm/rmap.c b/mm/rmap.c
index c56fab5826c1..c0295282928b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1205,7 +1205,7 @@ void page_add_file_rmap(struct page *page, bool compound)
 	VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
 	lock_page_memcg(page);
 	if (compound && PageTransHuge(page)) {
-		for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
+		for (i = 0, nr = 0; i < thp_nr_pages(page); i++) {
 			if (atomic_inc_and_test(&page[i]._mapcount))
 				nr++;
 		}
@@ -1246,7 +1246,7 @@ static void page_remove_file_rmap(struct page *page, bool compound)
 
 	/* page still mapped by someone else? */
 	if (compound && PageTransHuge(page)) {
-		for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
+		for (i = 0, nr = 0; i < thp_nr_pages(page); i++) {
 			if (atomic_add_negative(-1, &page[i]._mapcount))
 				nr++;
 		}
@@ -1293,7 +1293,7 @@ static void page_remove_anon_compound_rmap(struct page *page)
 		 * Subpages can be mapped with PTEs too. Check how many of
 		 * them are still mapped.
 		 */
-		for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
+		for (i = 0, nr = 0; i < thp_nr_pages(page); i++) {
 			if (atomic_add_negative(-1, &page[i]._mapcount))
 				nr++;
 		}
@@ -1303,10 +1303,10 @@ static void page_remove_anon_compound_rmap(struct page *page)
 		 * page of the compound page is unmapped, but at least one
 		 * small page is still mapped.
 		 */
-		if (nr && nr < HPAGE_PMD_NR)
+		if (nr && nr < thp_nr_pages(page))
 			deferred_split_huge_page(page);
 	} else {
-		nr = HPAGE_PMD_NR;
+		nr = thp_nr_pages(page);
 	}
 
 	if (unlikely(PageMlocked(page)))
-- 
2.26.2