mm: Drop reliable_reserve_size

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SK3S
CVE: NA

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

Commit 368d710d ("mm: Fallback to non-mirrored region below low watermark")
already set the default value of reliable_reserve_size to zero which will
disable reliable watermark check by default.

With this patch, code related to this mechanism is removed since no one use
this watermark check.
Signed-off-by: NMa Wupeng <mawupeng1@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

include/linux/mem_reliable.h

@@ -24,7 +24,6 @@ DECLARE_PER_CPU(long, nr_reliable_buddy_pages);
 
 extern struct percpu_counter pagecache_reliable_pages;
 extern struct percpu_counter anon_reliable_pages;
-extern unsigned long nr_reliable_reserve_pages __read_mostly;
 extern long shmem_reliable_nr_page __read_mostly;
 
 extern void add_reliable_mem_size(long sz);
@@ -118,21 +117,6 @@ static inline void mem_reliable_buddy_counter(struct page *page, int nr_page)
 		this_cpu_add(nr_reliable_buddy_pages, nr_page);
 }
 
-/* reserve mirrored memory for kernel usage */
-static inline bool mem_reliable_watermark_ok(int nr_page)
-{
-	long sum = 0;
-	int cpu;
-
-	if (!reliable_allow_fb_enabled())
-		return true;
-
-	for_each_possible_cpu(cpu)
-		sum += per_cpu(nr_reliable_buddy_pages, cpu);
-
-	return sum > nr_reliable_reserve_pages;
-}
-
 static inline bool mem_reliable_shmem_limit_check(void)
 {
 	return percpu_counter_read_positive(&reliable_shmem_used_nr_page) <
@@ -178,7 +162,6 @@ static inline void shmem_reliable_page_counter(struct page *page, int nr_page)
 static inline bool pagecache_reliable_is_enabled(void) { return false; }
 static inline bool mem_reliable_status(void) { return false; }
 static inline void mem_reliable_buddy_counter(struct page *page, int nr_page) {}
-static inline bool mem_reliable_watermark_ok(int nr_page) { return true; }
 static inline bool mem_reliable_shmem_limit_check(void) { return true; }
 static inline void reliable_lru_add(enum lru_list lru,
 					       struct page *page,

mm/mem_reliable.c

@@ -11,8 +11,6 @@
 #include <linux/oom.h>
 #include <linux/crash_dump.h>
 
-#define MEM_RELIABLE_RESERVE_MIN 0
-
 enum mem_reliable_types {
 	MEM_RELIABLE_ALL,
 	MEM_RELIABLE_FALLBACK,
@@ -31,7 +29,6 @@ bool reliable_allow_fallback __read_mostly = true;
 bool shmem_reliable __read_mostly = true;
 struct percpu_counter reliable_shmem_used_nr_page __read_mostly;
 DEFINE_PER_CPU(long, nr_reliable_buddy_pages);
-unsigned long nr_reliable_reserve_pages = MEM_RELIABLE_RESERVE_MIN / PAGE_SIZE;
 long shmem_reliable_nr_page = LONG_MAX;
 
 bool pagecache_use_reliable_mem __read_mostly = true;
@@ -338,29 +335,6 @@ int reliable_debug_handler(struct ctl_table *table, int write,
 	return ret;
 }
 
-static unsigned long sysctl_reliable_reserve_size = MEM_RELIABLE_RESERVE_MIN;
-
-int reliable_reserve_size_handler(struct ctl_table *table, int write,
-	void __user *buffer, size_t *length, loff_t *ppos)
-{
-	unsigned long *data_ptr = (unsigned long *)(table->data);
-	unsigned long old = *data_ptr;
-	int ret;
-
-	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
-	if (ret == 0 && write) {
-		if (*data_ptr > total_reliable_mem_sz() ||
-		    *data_ptr < MEM_RELIABLE_RESERVE_MIN) {
-			*data_ptr = old;
-			return -EINVAL;
-		}
-
-		nr_reliable_reserve_pages = *data_ptr / PAGE_SIZE;
-	}
-
-	return ret;
-}
-
 #ifdef CONFIG_SHMEM
 static unsigned long sysctl_shmem_reliable_bytes_limit = ULONG_MAX;
 
@@ -417,13 +391,6 @@ static struct ctl_table reliable_ctl_table[] = {
 		.mode = 0600,
 		.proc_handler = reliable_debug_handler,
 	},
-	{
-		.procname = "reliable_reserve_size",
-		.data = &sysctl_reliable_reserve_size,
-		.maxlen = sizeof(sysctl_reliable_reserve_size),
-		.mode = 0644,
-		.proc_handler = reliable_reserve_size_handler,
-	},
 #ifdef CONFIG_SHMEM
 	{
 		.procname = "shmem_reliable_bytes_limit",

mm/page_alloc.c

@@ -4649,10 +4649,6 @@ static inline bool check_after_alloc(gfp_t *gfp_mask, unsigned int order,
 	if (*gfp_mask & __GFP_NOFAIL)
 		goto out;
 
-	/* check water mark, reserver mirrored mem for kernel */
-	if (!mem_reliable_watermark_ok(1 << order))
-		goto out_free_page;
-
 	/* percpu counter is not initialized, ignore limit check */
 	if (!mem_reliable_counter_initialized())
 		goto out;