mm: Introduce reliable flag for user task

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

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

Adding reliable flag for user task. User task with reliable flag can
only alloc memory from mirrored region. PF_RELIABLE is added to represent
the task's reliable flag.

- For init task, which is regarded as as special task which alloc memory
  from mirrored region.

- For normal user tasks, The reliable flag can be set via procfs interface
  shown as below and can be inherited via fork().

User can change a user task's reliable flag by

	$ echo [0/1] > /proc/<pid>/reliable

and check a user task's reliable flag by

	$ cat /proc/<pid>/reliable

Note, global init task's reliable file can not be accessed.
Signed-off-by: NPeng Wu <wupeng58@huawei.com>
Signed-off-by: NMa Wupeng <mawupeng1@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

fs/proc/base.c

@@ -1222,6 +1222,96 @@ static const struct file_operations proc_oom_score_adj_operations = {
 	.llseek		= default_llseek,
 };
 
+#ifdef CONFIG_MEMORY_RELIABLE
+static inline int reliable_check(struct task_struct *task, struct pid *pid)
+{
+	if (!mem_reliable_is_enabled())
+		return -EPERM;
+
+	if (is_global_init(task))
+		return -EPERM;
+
+	if (!task->mm || (task->flags & PF_KTHREAD) ||
+	    (task->flags & PF_EXITING))
+		return -EPERM;
+
+	return 0;
+}
+
+static ssize_t reliable_read(struct file *file, char __user *buf,
+		size_t count, loff_t *ppos)
+{
+	struct task_struct *task = get_proc_task(file_inode(file));
+	struct pid *pid = proc_pid(file_inode(file));
+	char buffer[PROC_NUMBUF];
+	size_t len;
+	short val;
+	int err;
+
+	if (!task)
+		return -ESRCH;
+
+	err = reliable_check(task, pid);
+	if (err) {
+		put_task_struct(task);
+		return err;
+	}
+
+	val = task->flags & PF_RELIABLE ? 1 : 0;
+	put_task_struct(task);
+	len = snprintf(buffer, sizeof(buffer), "%hd\n", val);
+	return simple_read_from_buffer(buf, count, ppos, buffer, len);
+}
+
+static ssize_t reliable_write(struct file *file, const char __user *buf,
+		size_t count, loff_t *ppos)
+{
+	struct task_struct *task = get_proc_task(file_inode(file));
+	struct pid *pid = proc_pid(file_inode(file));
+	char buffer[PROC_NUMBUF];
+	int val;
+	int err;
+
+	if (!task)
+		return -ESRCH;
+
+	err = reliable_check(task, pid);
+	if (err)
+		goto out;
+
+	memset(buffer, 0, sizeof(buffer));
+	if (count > sizeof(buffer) - 1)
+		count = sizeof(buffer) - 1;
+	if (copy_from_user(buffer, buf, count)) {
+		err = -EFAULT;
+		goto out;
+	}
+
+	err = kstrtoint(strstrip(buffer), 0, &val);
+	if (err)
+		goto out;
+	if (val != 0 && val != 1) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	if (val == 1)
+		task->flags |= PF_RELIABLE;
+	else
+		task->flags &= ~PF_RELIABLE;
+
+out:
+	put_task_struct(task);
+	return err < 0 ? err : count;
+}
+
+static const struct file_operations proc_reliable_operations = {
+	.read       = reliable_read,
+	.write      = reliable_write,
+	.llseek     = generic_file_llseek,
+};
+#endif
+
 #ifdef CONFIG_AUDITSYSCALL
 #define TMPBUFLEN 11
 static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
@@ -3029,6 +3119,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 	ONE("oom_score",  S_IRUGO, proc_oom_score),
 	REG("oom_adj",    S_IRUGO|S_IWUSR, proc_oom_adj_operations),
 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
+#ifdef CONFIG_MEMORY_RELIABLE
+	REG("reliable", S_IRUGO|S_IWUSR, proc_reliable_operations),
+#endif
 #ifdef CONFIG_AUDITSYSCALL
 	REG("loginuid",   S_IWUSR|S_IRUGO, proc_loginuid_operations),
 	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
@@ -3419,6 +3512,9 @@ static const struct pid_entry tid_base_stuff[] = {
 	ONE("oom_score", S_IRUGO, proc_oom_score),
 	REG("oom_adj",   S_IRUGO|S_IWUSR, proc_oom_adj_operations),
 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
+#ifdef CONFIG_MEMORY_RELIABLE
+	REG("reliable", S_IRUGO|S_IWUSR, proc_reliable_operations),
+#endif
 #ifdef CONFIG_AUDITSYSCALL
 	REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),
 	REG("sessionid",  S_IRUGO, proc_sessionid_operations),

include/linux/sched.h

@@ -1421,6 +1421,7 @@ extern struct pid *cad_pid;
  */
 #define PF_IDLE			0x00000002	/* I am an IDLE thread */
 #define PF_EXITING		0x00000004	/* Getting shut down */
+#define PF_RELIABLE		0x00000008	/* Allocate from reliable memory */
 #define PF_VCPU			0x00000010	/* I'm a virtual CPU */
 #define PF_WQ_WORKER		0x00000020	/* I'm a workqueue worker */
 #define PF_FORKNOEXEC		0x00000040	/* Forked but didn't exec */

mm/page_alloc.c

@@ -4571,6 +4571,9 @@ static inline void prepare_before_alloc(gfp_t *gfp_mask)
 
 	if (gfp_ori & ___GFP_RELIABILITY)
 		*gfp_mask |= ___GFP_RELIABILITY;
+
+	if (current->flags & PF_RELIABLE || is_global_init(current))
+		*gfp_mask |= ___GFP_RELIABILITY;
 }
 
 /*