mm: mem_reliable: Initialize reliable_nr_page when mm_init()

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6RKHX
CVE: NA

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

After the fork operation, it is erroneous for the child process to have a
reliable page size twice that of its parent process.

Upon examining the mm_struct structure, it was discovered that
reliable_nr_page should be initialized to 0, similar to how RSS is
initialized during mm_init(). This particular problem that arises during
forking is merely one such example.

To resolve this issue, it is recommended to set reliable_nr_page to 0
during the mm_init() operation.

Fixes: 094eaabb ("proc: Count reliable memory usage of reliable tasks")
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

@@ -123,6 +123,13 @@ static inline bool mem_reliable_shmem_limit_check(void)
 	       shmem_reliable_nr_page;
 }
 
+static inline void reliable_clear_page_counter(struct mm_struct *mm)
+{
+	if (!mem_reliable_is_enabled())
+		return;
+
+	atomic_long_set(&mm->reliable_nr_page, 0);
+}
 #else
 #define reliable_enabled 0
 #define reliable_allow_fb_enabled() false
@@ -171,6 +178,7 @@ static inline void reliable_lru_add_batch(int zid, enum lru_list lru,
 						     int val) {}
 
 static inline bool mem_reliable_counter_initialized(void) { return false; }
+static inline void reliable_clear_page_counter(struct mm_struct *mm) {}
 #endif
 
 #endif

kernel/fork.c

@@ -1007,6 +1007,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
 	atomic_long_set(&mm->locked_vm, 0);
 	mm->pinned_vm = 0;
 	memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
+	reliable_clear_page_counter(mm);
 	spin_lock_init(&mm->page_table_lock);
 	spin_lock_init(&mm->arg_lock);
 	mm_init_cpumask(mm);