anolis: mm: avoid lru_gen_del_page if kidled is enabled

ANBZ: #6676

If LRU_GEN is disabled and kidled is enabled, the page flags of mglru has been
reused by kidled. However, lru_gen_del_page is not covered by lru_gen_enabled(),
thus it might change the page state.
Reviewed-by: Xu Yu <xuyu@linux.alibaba.com>
Link: https://gitee.com/anolis/cloud-kernel/pulls/2232

include/linux/kidled.h

@@ -96,6 +96,8 @@ enum kidled_scan_type {
 #define KIDLED_IS_BUCKET_INVALID(buckets)	\
 	(buckets[0] == KIDLED_INVALID_BUCKET)
 
+DECLARE_STATIC_KEY_FALSE(kidled_enabled_key);
+
 static inline bool kidled_is_slab_scanned(unsigned short slab_age,
 					  unsigned long scan_rounds)
 {
@@ -304,6 +306,11 @@ static inline void kidled_set_scan_duration(u16 duration)
 			       duration, NULL);
 }
 
+static inline bool is_kidled_enabled(void)
+{
+	return static_branch_unlikely(&kidled_enabled_key);
+}
+
 /*
  * Caller must specify the original scan period, avoid the race between
  * the double operation and user's updates through sysfs interface.
@@ -423,8 +430,11 @@ static inline unsigned int kidled_get_current_scan_duration(void)
 	return 0;
 }
 
+static inline bool is_kidled_enabled(void)
+{
+	return false;
+}
+
 #endif /* CONFIG_KIDLED */
 
-#define is_kidled_enabled() kidled_get_current_scan_duration()
-
 #endif /* _LINUX_MM_KIDLED_H */

include/linux/mm_inline.h

@@ -4,6 +4,7 @@
 
 #include <linux/huge_mm.h>
 #include <linux/swap.h>
+#include <linux/kidled.h>
 
 /**
  * page_is_file_lru - should the page be on a file LRU or anon LRU?
@@ -273,7 +274,7 @@ static inline bool lru_gen_del_page(struct lruvec *lruvec, struct page *page, bo
 	unsigned long flags;
 	int gen = page_lru_gen(page);
 
-	if (gen < 0)
+	if (gen < 0 || is_kidled_enabled())
 		return false;
 
 	VM_WARN_ON_ONCE_PAGE(PageActive(page), page);

include/linux/page-flags.h

@@ -1004,6 +1004,8 @@ static inline void ClearPageSlabPfmemalloc(struct page *page)
 /*
  * Flags checked when a page is freed.  Pages being freed should not have
  * these flags set.  It they are, there is a problem.
+ *
+ * To avoid conflict with kidled, we skip to check LRU_GEN_MASK.
  */
 #define PAGE_FLAGS_CHECK_AT_FREE				\
 	(1UL << PG_lru		| 1UL << PG_locked	|	\
@@ -1011,7 +1013,7 @@ static inline void ClearPageSlabPfmemalloc(struct page *page)
 	 1UL << PG_writeback	| 1UL << PG_reserved	|	\
 	 1UL << PG_slab		| 1UL << PG_active 	|	\
 	 1UL << PG_unevictable	| __PG_MLOCKED		|	\
-	 __PG_DUP		| LRU_GEN_MASK)
+	 __PG_DUP)
 
 /*
  * Flags checked when a page is prepped for return by the page allocator.

mm/kidled.c

@@ -68,6 +68,8 @@
 #define __kidled_ref __ref
 #endif
 
+DEFINE_STATIC_KEY_FALSE(kidled_enabled_key);
+
 unsigned int kidled_scan_target __read_mostly = KIDLED_SCAN_PAGE;
 struct kidled_scan_control kidled_scan_control;
 /*
@@ -785,6 +787,10 @@ static inline bool kidled_should_run(struct kidled_scan_control *p,
 			kidled_reset();
 #endif
 		}
+
+		if (!scan_control.duration)
+			static_branch_disable(&kidled_enabled_key);
+
 		*p = scan_control;
 		*new = true;
 	} else if (unlikely(!kidled_is_scan_target_equal(p))) {
@@ -1078,6 +1084,13 @@ static ssize_t kidled_scan_period_store(struct kobject *kobj,
 		return -EINVAL;
 	}
 
+	/*
+	 * To avoid situation like lru_gen >= 0 && kidled disabled, disable
+	 * enabled_key after reset.
+	 */
+	if (secs)
+		static_branch_enable(&kidled_enabled_key);
+
 	kidled_set_scan_duration(secs);
 	wake_up_interruptible(&kidled_wait);
 	kidled_slab_scan_enabled();