linux-kernel - [PATCH v6 39/99] mm: Convert khugepaged_scan

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Message-Id: <20180117202203.19756-40-willy@infradead.org>
Date:   Wed, 17 Jan 2018 12:21:03 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     linux-kernel@...r.kernel.org
Cc:     Matthew Wilcox <mawilcox@...rosoft.com>, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-nilfs@...r.kernel.org, linux-btrfs@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-usb@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Stefano Stabellini <sstabellini@...nel.org>,
        iommu@...ts.linux-foundation.org, linux-remoteproc@...r.kernel.org,
        linux-s390@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
        cgroups@...r.kernel.org, linux-sh@...r.kernel.org,
        David Howells <dhowells@...hat.com>
Subject: [PATCH v6 39/99] 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 9f49d0cd61c2..15f1b2d81a69 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1534,8 +1534,7 @@ 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->pages, start);
 	int present, swap;
 	int node = NUMA_NO_NODE;
 	int result = SCAN_SUCCEED;
@@ -1544,17 +1543,11 @@ 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->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;
@@ -1593,7 +1586,7 @@ 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();
 		}
 	}
-- 
2.15.1