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Commit 1d5f0acb authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
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proc, oom_adj: extract oom_score_adj setting into a helper 

Currently we have two proc interfaces to set oom_score_adj.  The legacy
/proc/<pid>/oom_adj and /proc/<pid>/oom_score_adj which both have their
specific handlers.  Big part of the logic is duplicated so extract the
common code into __set_oom_adj helper.  Legacy knob still expects some
details slightly different so make sure those are handled same way - e.g.
the legacy mode ignores oom_score_adj_min and it warns about the usage.

This patch shouldn't introduce any functional changes.

Link: http://lkml.kernel.org/r/1466426628-15074-4-git-send-email-mhocko@kernel.org


Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f913da59

fs/proc/base.c

+43 −51
Original line number Diff line number Diff line
@@ -1037,7 +1037,47 @@ static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count, 
	return simple_read_from_buffer(buf, count, ppos, buffer, len);

}



static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)

{

	static DEFINE_MUTEX(oom_adj_mutex);

	struct task_struct *task;

	int err = 0;



	task = get_proc_task(file_inode(file));

	if (!task)

		return -ESRCH;



	mutex_lock(&oom_adj_mutex);

	if (legacy) {

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

				!capable(CAP_SYS_RESOURCE)) {

			err = -EACCES;

			goto err_unlock;

		}

		/*

		 * /proc/pid/oom_adj is provided for legacy purposes, ask users to use

		 * /proc/pid/oom_score_adj instead.

		 */

		pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",

			  current->comm, task_pid_nr(current), task_pid_nr(task),

			  task_pid_nr(task));

	} else {

		if ((short)oom_adj < task->signal->oom_score_adj_min &&

				!capable(CAP_SYS_RESOURCE)) {

			err = -EACCES;

			goto err_unlock;

		}

	}



	task->signal->oom_score_adj = oom_adj;

	if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))

		task->signal->oom_score_adj_min = (short)oom_adj;

	trace_oom_score_adj_update(task);

err_unlock:

	mutex_unlock(&oom_adj_mutex);

	put_task_struct(task);

	return err;

}



/*

 * /proc/pid/oom_adj exists solely for backwards compatibility with previous
@@ -1052,7 +1092,6 @@ static DEFINE_MUTEX(oom_adj_mutex); 
static ssize_t oom_adj_write(struct file *file, const char __user *buf,

			     size_t count, loff_t *ppos)

{

	struct task_struct *task;

	char buffer[PROC_NUMBUF];

	int oom_adj;

	int err;
@@ -1074,12 +1113,6 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf, 
		goto out;

	}



	task = get_proc_task(file_inode(file));

	if (!task) {

		err = -ESRCH;

		goto out;

	}



	/*

	 * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum

	 * value is always attainable.
@@ -1089,26 +1122,7 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf, 
	else

		oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;



	mutex_lock(&oom_adj_mutex);

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

	    !capable(CAP_SYS_RESOURCE)) {

		err = -EACCES;

		goto err_unlock;

	}



	/*

	 * /proc/pid/oom_adj is provided for legacy purposes, ask users to use

	 * /proc/pid/oom_score_adj instead.

	 */

	pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",

		  current->comm, task_pid_nr(current), task_pid_nr(task),

		  task_pid_nr(task));



	task->signal->oom_score_adj = oom_adj;

	trace_oom_score_adj_update(task);

err_unlock:

	mutex_unlock(&oom_adj_mutex);

	put_task_struct(task);

	err = __set_oom_adj(file, oom_adj, true);

out:

	return err < 0 ? err : count;

}
@@ -1138,7 +1152,6 @@ static ssize_t oom_score_adj_read(struct file *file, char __user *buf, 
static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,

					size_t count, loff_t *ppos)

{

	struct task_struct *task;

	char buffer[PROC_NUMBUF];

	int oom_score_adj;

	int err;
@@ -1160,28 +1173,7 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf, 
		goto out;

	}



	task = get_proc_task(file_inode(file));

	if (!task) {

		err = -ESRCH;

		goto out;

	}



	mutex_lock(&oom_adj_mutex);

	if ((short)oom_score_adj < task->signal->oom_score_adj_min &&

			!capable(CAP_SYS_RESOURCE)) {

		err = -EACCES;

		goto err_unlock;

	}



	task->signal->oom_score_adj = (short)oom_score_adj;

	if (has_capability_noaudit(current, CAP_SYS_RESOURCE))

		task->signal->oom_score_adj_min = (short)oom_score_adj;



	trace_oom_score_adj_update(task);



err_unlock:

	mutex_unlock(&oom_adj_mutex);

	put_task_struct(task);

	err = __set_oom_adj(file, oom_score_adj, false);

out:

	return err < 0 ? err : count;

}