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Commit 723548bf authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
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oom: rewrite error handling for oom_adj and oom_score_adj tunables 



It's better to use proper error handling in oom_adjust_write() and
oom_score_adj_write() instead of duplicating the locking order on various
exit paths.

Suggested-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1e99bad0

fs/proc/base.c

+48 −35
Original line number Diff line number Diff line
@@ -1023,36 +1023,39 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, 
	memset(buffer, 0, sizeof(buffer));

	if (count > sizeof(buffer) - 1)

		count = sizeof(buffer) - 1;

	if (copy_from_user(buffer, buf, count))

		return -EFAULT;

	if (copy_from_user(buffer, buf, count)) {

		err = -EFAULT;

		goto out;

	}



	err = strict_strtol(strstrip(buffer), 0, &oom_adjust);

	if (err)

		return -EINVAL;

		goto out;

	if ((oom_adjust < OOM_ADJUST_MIN || oom_adjust > OOM_ADJUST_MAX) &&

	     oom_adjust != OOM_DISABLE)

		return -EINVAL;

	     oom_adjust != OOM_DISABLE) {

		err = -EINVAL;

		goto out;

	}



	task = get_proc_task(file->f_path.dentry->d_inode);

	if (!task)

		return -ESRCH;

	if (!task) {

		err = -ESRCH;

		goto out;

	}

	if (!lock_task_sighand(task, &flags)) {

		put_task_struct(task);

		return -ESRCH;

		err = -ESRCH;

		goto err_task_struct;

	}



	if (oom_adjust < task->signal->oom_adj && !capable(CAP_SYS_RESOURCE)) {

		unlock_task_sighand(task, &flags);

		put_task_struct(task);

		return -EACCES;

		err = -EACCES;

		goto err_sighand;

	}



	task_lock(task);

	if (!task->mm) {

		task_unlock(task);

		unlock_task_sighand(task, &flags);

		put_task_struct(task);

		return -EINVAL;

		err = -EINVAL;

		goto err_task_lock;

	}



	if (oom_adjust != task->signal->oom_adj) {
@@ -1080,11 +1083,14 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, 
	else

		task->signal->oom_score_adj = (oom_adjust * OOM_SCORE_ADJ_MAX) /

								-OOM_DISABLE;

err_task_lock:

	task_unlock(task);

err_sighand:

	unlock_task_sighand(task, &flags);

err_task_struct:

	put_task_struct(task);



	return count;

out:

	return err < 0 ? err : count;

}



static const struct file_operations proc_oom_adjust_operations = {
@@ -1125,36 +1131,39 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf, 
	memset(buffer, 0, sizeof(buffer));

	if (count > sizeof(buffer) - 1)

		count = sizeof(buffer) - 1;

	if (copy_from_user(buffer, buf, count))

		return -EFAULT;

	if (copy_from_user(buffer, buf, count)) {

		err = -EFAULT;

		goto out;

	}



	err = strict_strtol(strstrip(buffer), 0, &oom_score_adj);

	if (err)

		return -EINVAL;

		goto out;

	if (oom_score_adj < OOM_SCORE_ADJ_MIN ||

			oom_score_adj > OOM_SCORE_ADJ_MAX)

		return -EINVAL;

			oom_score_adj > OOM_SCORE_ADJ_MAX) {

		err = -EINVAL;

		goto out;

	}



	task = get_proc_task(file->f_path.dentry->d_inode);

	if (!task)

		return -ESRCH;

	if (!task) {

		err = -ESRCH;

		goto out;

	}

	if (!lock_task_sighand(task, &flags)) {

		put_task_struct(task);

		return -ESRCH;

		err = -ESRCH;

		goto err_task_struct;

	}

	if (oom_score_adj < task->signal->oom_score_adj &&

			!capable(CAP_SYS_RESOURCE)) {

		unlock_task_sighand(task, &flags);

		put_task_struct(task);

		return -EACCES;

		err = -EACCES;

		goto err_sighand;

	}



	task_lock(task);

	if (!task->mm) {

		task_unlock(task);

		unlock_task_sighand(task, &flags);

		put_task_struct(task);

		return -EINVAL;

		err = -EINVAL;

		goto err_task_lock;

	}

	if (oom_score_adj != task->signal->oom_score_adj) {

		if (oom_score_adj == OOM_SCORE_ADJ_MIN)
@@ -1172,10 +1181,14 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf, 
	else

		task->signal->oom_adj = (oom_score_adj * OOM_ADJUST_MAX) /

							OOM_SCORE_ADJ_MAX;

err_task_lock:

	task_unlock(task);

err_sighand:

	unlock_task_sighand(task, &flags);

err_task_struct:

	put_task_struct(task);

	return count;

out:

	return err < 0 ? err : count;

}



static const struct file_operations proc_oom_score_adj_operations = {