[PATCH v3 4/8] mm: use zone lock guard in set_migratetype_isolate()

Dmitry Ilvokhin
2026-04-29T12:02:36Z

Use spinlock_irqsave scoped lock guard in set_migratetype_isolate() to
replace the explicit lock/unlock pattern with automatic scope-based
cleanup. The scoped variant is used to keep dump_page() outside the
locked section to avoid a lockdep splat.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Dmitry Ilvokhin <d@ilvokhin.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
mm/page_isolation.c | 60 ++++++++++++++++++++-------------------------
1 file changed, 26 insertions(+), 34 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 9d606052dd80..7a9d631945a3 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -167,48 +167,40 @@ static int set_migratetype_isolate(struct page *page, enum pb_isolate_mode mode,
{
struct zone *zone = page_zone(page);
struct page *unmovable;
- unsigned long flags;
unsigned long check_unmovable_start, check_unmovable_end;

if (PageUnaccepted(page))
accept_page(page);

- spin_lock_irqsave(&zone->lock, flags);
-
- /*
- * We assume the caller intended to SET migrate type to isolate.
- * If it is already set, then someone else must have raced and
- * set it before us.
- */
- if (is_migrate_isolate_page(page)) {
- spin_unlock_irqrestore(&zone->lock, flags);
- return -EBUSY;
- }
-
- /*
- * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
- * We just check MOVABLE pages.
- *
- * Pass the intersection of [start_pfn, end_pfn) and the page's pageblock
- * to avoid redundant checks.
- */
- check_unmovable_start = max(page_to_pfn(page), start_pfn);
- check_unmovable_end = min(pageblock_end_pfn(page_to_pfn(page)),
- end_pfn);
-
- unmovable = has_unmovable_pages(check_unmovable_start, check_unmovable_end,
- mode);
- if (!unmovable) {
- if (!pageblock_isolate_and_move_free_pages(zone, page)) {
- spin_unlock_irqrestore(&zone->lock, flags);
+ scoped_guard(spinlock_irqsave, &zone->lock) {
+ /*
+ * We assume the caller intended to SET migrate type to
+ * isolate. If it is already set, then someone else must have
+ * raced and set it before us.
+ */
+ if (is_migrate_isolate_page(page))
return -EBUSY;
+
+ /*
+ * FIXME: Now, memory hotplug doesn't call shrink_slab() by
+ * itself. We just check MOVABLE pages.
+ *
+ * Pass the intersection of [start_pfn, end_pfn) and the page's
+ * pageblock to avoid redundant checks.
+ */
+ check_unmovable_start = max(page_to_pfn(page), start_pfn);
+ check_unmovable_end = min(pageblock_end_pfn(page_to_pfn(page)),
+ end_pfn);
+
+ unmovable = has_unmovable_pages(check_unmovable_start,
+ check_unmovable_end, mode);
+ if (!unmovable) {
+ if (!pageblock_isolate_and_move_free_pages(zone, page))
+ return -EBUSY;
+ zone->nr_isolate_pageblock++;
+ return 0;
}
- zone->nr_isolate_pageblock++;
- spin_unlock_irqrestore(&zone->lock, flags);
- return 0;
}
-
- spin_unlock_irqrestore(&zone->lock, flags);
if (mode == PB_ISOLATE_MODE_MEM_OFFLINE) {
/*
* printk() with zone->lock held will likely trigger a
--
2.52.0