linux-kernel - [PATCH RFC 03/29] mm/zsmalloc: drop PageIsolated() related VM_BUG

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Message-ID: <20250618174014.1168640-4-david@redhat.com>
Date: Wed, 18 Jun 2025 19:39:46 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
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Subject: [PATCH RFC 03/29] mm/zsmalloc: drop PageIsolated() related VM_BUG_ONs

Let's drop these checks; these are conditions the core migration code
must make sure will hold either way, no need to double check.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/zpdesc.h   | 5 -----
 mm/zsmalloc.c | 5 -----
 2 files changed, 10 deletions(-)

diff --git a/mm/zpdesc.h b/mm/zpdesc.h
index d3df316e5bb7b..5cb7e3de43952 100644
--- a/mm/zpdesc.h
+++ b/mm/zpdesc.h
@@ -168,11 +168,6 @@ static inline void __zpdesc_clear_zsmalloc(struct zpdesc *zpdesc)
 	__ClearPageZsmalloc(zpdesc_page(zpdesc));
 }
 
-static inline bool zpdesc_is_isolated(struct zpdesc *zpdesc)
-{
-	return PageIsolated(zpdesc_page(zpdesc));
-}
-
 static inline struct zone *zpdesc_zone(struct zpdesc *zpdesc)
 {
 	return page_zone(zpdesc_page(zpdesc));
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 999b513c7fdff..7f1431f2be98f 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1719,8 +1719,6 @@ static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
 	 * Page is locked so zspage couldn't be destroyed. For detail, look at
 	 * lock_zspage in free_zspage.
 	 */
-	VM_BUG_ON_PAGE(PageIsolated(page), page);
-
 	return true;
 }
 
@@ -1739,8 +1737,6 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	unsigned long old_obj, new_obj;
 	unsigned int obj_idx;
 
-	VM_BUG_ON_PAGE(!zpdesc_is_isolated(zpdesc), zpdesc_page(zpdesc));
-
 	/* The page is locked, so this pointer must remain valid */
 	zspage = get_zspage(zpdesc);
 	pool = zspage->pool;
@@ -1811,7 +1807,6 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 
 static void zs_page_putback(struct page *page)
 {
-	VM_BUG_ON_PAGE(!PageIsolated(page), page);
 }
 
 static const struct movable_operations zsmalloc_mops = {
-- 
2.49.0