linux-kernel - [PATCH v9 41/61] mm: Convert khugepaged_scan

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Message-Id: <20180313132639.17387-42-willy@infradead.org>
Date:   Tue, 13 Mar 2018 06:26:19 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Matthew Wilcox <mawilcox@...rosoft.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>,
        linux-nilfs@...r.kernel.org
Subject: [PATCH v9 41/61] mm: Convert khugepaged_scan_shmem to XArray

From: Matthew Wilcox <mawilcox@...rosoft.com>

Slightly shorter and easier to read code.

Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 mm/khugepaged.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 3685c8e2b3dc..39e260a0639c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1533,8 +1533,7 @@ static void khugepaged_scan_shmem(struct mm_struct *mm,
 		pgoff_t start, struct page **hpage)
 {
 	struct page *page = NULL;
-	struct radix_tree_iter iter;
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, start);
 	int present, swap;
 	int node = NUMA_NO_NODE;
 	int result = SCAN_SUCCEED;
@@ -1543,17 +1542,11 @@ static void khugepaged_scan_shmem(struct mm_struct *mm,
 	swap = 0;
 	memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
-		if (iter.index >= start + HPAGE_PMD_NR)
-			break;
-
-		page = radix_tree_deref_slot(slot);
-		if (radix_tree_deref_retry(page)) {
-			slot = radix_tree_iter_retry(&iter);
+	xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) {
+		if (xas_retry(&xas, page))
 			continue;
-		}
 
-		if (radix_tree_exception(page)) {
+		if (xa_is_value(page)) {
 			if (++swap > khugepaged_max_ptes_swap) {
 				result = SCAN_EXCEED_SWAP_PTE;
 				break;
@@ -1592,7 +1585,7 @@ static void khugepaged_scan_shmem(struct mm_struct *mm,
 		present++;
 
 		if (need_resched()) {
-			slot = radix_tree_iter_resume(slot, &iter);
+			xas_pause(&xas);
 			cond_resched_rcu();
 		}
 	}
-- 
2.16.1