linux-kernel - [PATCH v2 3/3] mm: handling Non-LRU pages returned by follow

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Date:   Sun, 14 Aug 2022 22:05:34 +0800
From:   Haiyue Wang <haiyue.wang@...el.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     akpm@...ux-foundation.org, david@...hat.com, linmiaohe@...wei.com,
        ying.huang@...el.com, songmuchun@...edance.com,
        naoya.horiguchi@...ux.dev, alex.sierra@....com,
        Haiyue Wang <haiyue.wang@...el.com>
Subject: [PATCH v2 3/3] mm: handling Non-LRU pages returned by follow_page

Add the missed put_page handling for handling Non-LRU pages returned by
follow_page with FOLL_GET flag set.

This is the second patch for fixing the commit
3218f8712d6b ("mm: handling Non-LRU pages returned by vm_normal_pages")

Signed-off-by: Haiyue Wang <haiyue.wang@...el.com>
---
 mm/huge_memory.c |  2 +-
 mm/ksm.c         | 10 ++++++++++
 mm/migrate.c     |  6 +++++-
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2ee6d38a1426..b2ba17c3dcd7 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2966,7 +2966,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
 		if (IS_ERR_OR_NULL(page))
 			continue;
 
-		if (!is_transparent_hugepage(page))
+		if (is_zone_device_page(page) || !is_transparent_hugepage(page))
 			goto next;
 
 		total++;
diff --git a/mm/ksm.c b/mm/ksm.c
index fe3e0a39f73a..1360bb52ada6 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -477,6 +477,10 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
 				FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE);
 		if (IS_ERR_OR_NULL(page))
 			break;
+		if (is_zone_device_page(page)) {
+			put_page(page);
+			break;
+		}
 		if (PageKsm(page))
 			ret = handle_mm_fault(vma, addr,
 					      FAULT_FLAG_WRITE | FAULT_FLAG_REMOTE,
@@ -562,10 +566,13 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item)
 	page = follow_page(vma, addr, FOLL_GET);
 	if (IS_ERR_OR_NULL(page))
 		goto out;
+	if (is_zone_device_page(page))
+		goto out_putpage;
 	if (PageAnon(page)) {
 		flush_anon_page(vma, page, addr);
 		flush_dcache_page(page);
 	} else {
+out_putpage:
 		put_page(page);
 out:
 		page = NULL;
@@ -2313,6 +2320,8 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
 				cond_resched();
 				continue;
 			}
+			if (is_zone_device_page(*page))
+				goto next_page;
 			if (PageAnon(*page)) {
 				flush_anon_page(vma, *page, ksm_scan.address);
 				flush_dcache_page(*page);
@@ -2327,6 +2336,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
 				mmap_read_unlock(mm);
 				return rmap_item;
 			}
+next_page:
 			put_page(*page);
 			ksm_scan.address += PAGE_SIZE;
 			cond_resched();
diff --git a/mm/migrate.c b/mm/migrate.c
index 5d304de3950b..fee12cd2f294 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1675,6 +1675,9 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
 	if (!page)
 		goto out;
 
+	if (is_zone_device_page(page))
+		goto out_putpage;
+
 	err = 0;
 	if (page_to_nid(page) == node)
 		goto out_putpage;
@@ -1869,7 +1872,8 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
 			goto set_status;
 
 		if (page) {
-			err = page_to_nid(page);
+			err = !is_zone_device_page(page) ? page_to_nid(page)
+							 : -ENOENT;
 			if (foll_flags & FOLL_GET)
 				put_page(page);
 		} else {
-- 
2.37.2