pagecache: add Kconfig to enable/disable the feature

euler inclusion
category: bugfix
CVE: NA
Bugzilla: 9580

---------------------------

Just add Kconfig to the feature.
Signed-off-by: Nzhongjiang <zhongjiang@huawei.com>
Reviewed-by: NJing Xiangfeng <jingxiangfeng@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

include/linux/pagemap.h

@@ -613,8 +613,10 @@ static inline int fault_in_pages_readable(const char __user *uaddr, int size)
 	return 0;
 }
 
+#ifdef CONFIG_SHRINK_PAGECACHE
 int add_to_page_cache(struct page *page, struct address_space *mapping,
 				pgoff_t index, gfp_t gfp_mask);
+#endif
 int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
 				pgoff_t index, gfp_t gfp_mask);
 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
@@ -624,6 +626,24 @@ extern void __delete_from_page_cache(struct page *page, void *shadow);
 int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
 void delete_from_page_cache_batch(struct address_space *mapping,
 				  struct pagevec *pvec);
+#ifndef CONFIG_SHRINK_PAGECACHE
+/*
+ * Like add_to_page_cache_locked, but used to add newly allocated pages:
+ * the page is new, so we can just run __SetPageLocked() against it.
+ */
+static inline int add_to_page_cache(struct page *page,
+	struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
+{
+	int error;
+
+	__SetPageLocked(page);
+	error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
+	if (unlikely(error))
+		__ClearPageLocked(page);
+
+	return error;
+}
+#endif
 
 static inline unsigned long dir_pages(struct inode *inode)
 {

include/linux/swap.h

@@ -367,6 +367,7 @@ extern int vm_swappiness;
 extern int remove_mapping(struct address_space *mapping, struct page *page);
 extern unsigned long vm_total_pages;
 
+#ifdef CONFIG_SHRINK_PAGECACHE
 extern unsigned long vm_cache_limit_ratio;
 extern unsigned long vm_cache_limit_ratio_min;
 extern unsigned long vm_cache_limit_ratio_max;
@@ -385,6 +386,7 @@ extern int cache_limit_ratio_sysctl_handler(struct ctl_table *table, int write,
 			void __user *buffer, size_t *length, loff_t *ppos);
 extern int cache_limit_mbytes_sysctl_handler(struct ctl_table *table, int write,
 			void __user *buffer, size_t *length, loff_t *ppos);
+#endif
 
 #ifdef CONFIG_NUMA
 extern int node_reclaim_mode;

kernel/sysctl.c

@@ -1364,6 +1364,7 @@ static struct ctl_table vm_table[] = {
 		.extra1		= &zero,
 		.extra2		= &one_hundred,
 	},
+#ifdef CONFIG_SHRINK_PAGECACHE
 	{
 		.procname       = "cache_reclaim_s",
 		.data           = &vm_cache_reclaim_s,
@@ -1382,6 +1383,7 @@ static struct ctl_table vm_table[] = {
 		.extra1         = &vm_cache_reclaim_weight_min,
 		.extra2         = &vm_cache_reclaim_weight_max,
 	},
+#endif
 #ifdef CONFIG_HUGETLB_PAGE
 	{
 		.procname	= "nr_hugepages",

mm/Kconfig

@@ -479,6 +479,19 @@ config FRONTSWAP
 
 	  If unsure, say Y to enable frontswap.
 
+config SHRINK_PAGECACHE
+	bool "Enable background thread to shrink the page cache"
+	depends on MMU
+	default n
+	help
+	  SHRINK_PAGECACHE means that we do not want to keep the large number
+	  of page cache in the system, Even though it will greatly improve the
+	  performance of the machine. But it is asked by the user to keep the
+	  free memory as much as possible. Apparently, it will influence the
+	  informace. hence, we should switch off the option if it is not necessary.
+
+	  if unsure, say N to disable the SHRINK_PAGECACHE.
+
 config CMA
 	bool "Contiguous Memory Allocator"
 	depends on HAVE_MEMBLOCK && MMU

mm/filemap.c

@@ -895,6 +895,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
 }
 EXPORT_SYMBOL(add_to_page_cache_locked);
 
+#ifdef CONFIG_SHRINK_PAGECACHE
 /*
  * Like add_to_page_cache_locked, but used to add newly allocated pages:
  * the page is new, so we can just run __SetPageLocked() against it.
@@ -914,6 +915,7 @@ int add_to_page_cache(struct page *page,
 	return error;
 }
 EXPORT_SYMBOL(add_to_page_cache);
+#endif
 
 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 				pgoff_t offset, gfp_t gfp_mask)

mm/page_alloc.c

@@ -8150,6 +8150,7 @@ bool set_hwpoison_free_buddy_page(struct page *page)
 }
 #endif
 
+#ifdef CONFIG_SHRINK_PAGECACHE
 unsigned long page_cache_over_limit(void)
 {
 	unsigned long lru_file, limit;
@@ -8217,3 +8218,4 @@ int cache_limit_mbytes_sysctl_handler(struct ctl_table *table, int write,
 
 	return 0;
 }
+#endif

mm/vmscan.c

@@ -166,6 +166,7 @@ int vm_swappiness = 60;
  */
 unsigned long vm_total_pages;
 
+#ifdef CONFIG_SHRINK_PAGECACHE
 unsigned long vm_cache_limit_ratio;
 unsigned long vm_cache_limit_ratio_min;
 unsigned long vm_cache_limit_ratio_max;
@@ -179,6 +180,7 @@ int vm_cache_reclaim_weight __read_mostly;
 int vm_cache_reclaim_weight_min;
 int vm_cache_reclaim_weight_max;
 static DEFINE_PER_CPU(struct delayed_work, vmscan_work);
+#endif
 
 static LIST_HEAD(shrinker_list);
 static DECLARE_RWSEM(shrinker_rwsem);
@@ -3517,8 +3519,10 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
 
 	count_vm_event(PAGEOUTRUN);
 
+#ifdef CONFIG_SHRINK_PAGECACHE
 	if (vm_cache_limit_mbytes && page_cache_over_limit())
 		shrink_page_cache(GFP_KERNEL);
+#endif
 
 	do {
 		unsigned long nr_reclaimed = sc.nr_reclaimed;
@@ -3902,6 +3906,7 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
 }
 #endif /* CONFIG_HIBERNATION */
 
+#ifdef CONFIG_SHRINK_PAGECACHE
 static unsigned long __shrink_page_cache(gfp_t mask)
 {
 	struct scan_control sc = {
@@ -4013,6 +4018,7 @@ static int kswapd_cpu_down_prep(unsigned int cpu)
 
 	return 0;
 }
+#endif
 
 /* It's optimal to keep kswapds on the same CPUs as their memory, but
    not required for correctness.  So if the last cpu in a node goes
@@ -4079,12 +4085,19 @@ static int __init kswapd_init(void)
 	swap_setup();
 	for_each_node_state(nid, N_MEMORY)
  		kswapd_run(nid);
+#ifdef CONFIG_SHRINK_PAGECACHE
 	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 					"mm/vmscan:online", kswapd_cpu_online,
 					kswapd_cpu_down_prep);
+#else
+	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+					"mm/vmscan:online", kswapd_cpu_online,
+					NULL);
+#endif
 	WARN_ON(ret < 0);
+#ifdef CONFIG_SHRINK_PAGECACHE
 	shrink_page_cache_init();
-
+#endif
 	return 0;
 }