linux-kernel - [PATCH v2 1/3] mm: revert handling Non-LRU pages returned by follow

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Message-Id: <20220814140534.363348-2-haiyue.wang@intel.com>
Date:   Sun, 14 Aug 2022 22:05:32 +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 1/3] mm: revert handling Non-LRU pages returned by follow_page

The commit
3218f8712d6b ("mm: handling Non-LRU pages returned by vm_normal_pages")
doesn't handle the follow_page with flag FOLL_GET correctly, this will
do get_page on page, it shouldn't just return directly without put_page.

So revert the related fix to prepare for clean patch to handle Non-LRU
pages returned by follow_page.

Signed-off-by: Haiyue Wang <haiyue.wang@...el.com>
---
 mm/huge_memory.c | 2 +-
 mm/ksm.c         | 6 +++---
 mm/migrate.c     | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8a7c1b344abe..2ee6d38a1426 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2963,7 +2963,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
 		/* FOLL_DUMP to ignore special (like zero) pages */
 		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
 
-		if (IS_ERR_OR_NULL(page) || is_zone_device_page(page))
+		if (IS_ERR_OR_NULL(page))
 			continue;
 
 		if (!is_transparent_hugepage(page))
diff --git a/mm/ksm.c b/mm/ksm.c
index 42ab153335a2..fe3e0a39f73a 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -475,7 +475,7 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
 		cond_resched();
 		page = follow_page(vma, addr,
 				FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE);
-		if (IS_ERR_OR_NULL(page) || is_zone_device_page(page))
+		if (IS_ERR_OR_NULL(page))
 			break;
 		if (PageKsm(page))
 			ret = handle_mm_fault(vma, addr,
@@ -560,7 +560,7 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item)
 		goto out;
 
 	page = follow_page(vma, addr, FOLL_GET);
-	if (IS_ERR_OR_NULL(page) || is_zone_device_page(page))
+	if (IS_ERR_OR_NULL(page))
 		goto out;
 	if (PageAnon(page)) {
 		flush_anon_page(vma, page, addr);
@@ -2308,7 +2308,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
 			if (ksm_test_exit(mm))
 				break;
 			*page = follow_page(vma, ksm_scan.address, FOLL_GET);
-			if (IS_ERR_OR_NULL(*page) || is_zone_device_page(*page)) {
+			if (IS_ERR_OR_NULL(*page)) {
 				ksm_scan.address += PAGE_SIZE;
 				cond_resched();
 				continue;
diff --git a/mm/migrate.c b/mm/migrate.c
index 6a1597c92261..3d5f0262ab60 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1672,7 +1672,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
 		goto out;
 
 	err = -ENOENT;
-	if (!page || is_zone_device_page(page))
+	if (!page)
 		goto out;
 
 	err = 0;
@@ -1863,7 +1863,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
 		if (IS_ERR(page))
 			goto set_status;
 
-		if (page && !is_zone_device_page(page)) {
+		if (page) {
 			err = page_to_nid(page);
 			put_page(page);
 		} else {
-- 
2.37.2