[PATCH] mm, oom: first step towards oom_kill_allocating_task deprecation

[Roman Gushchin]

The oom_kill_allocating_task sysctl which causes the OOM killer
to simple kill the allocating task is useless. Killing the random
task is not the best idea.

Nobody likes it, and hopefully nobody uses it.
We want to completely deprecate it at some point.

To make a first step towards deprecation, let's warn potential
users about deprecation plans.

Signed-off-by: Roman Gushchin <guro@xxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 kernel/sysctl.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 655686d546cb..9158f1980584 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -220,6 +220,17 @@ static int sysrq_sysctl_handler(struct ctl_table *table, int write,
 
 #endif
 
+static int proc_oom_kill_allocating_tasks(struct ctl_table *table, int write,
+				   void __user *buffer, size_t *lenp,
+				   loff_t *ppos)
+{
+	pr_warn_once("The oom_kill_allocating_task sysctl will be deprecated.\n"
+		     "If you're using it, please, report to "
+		     "linux-mm@xxxxxxxxxxxxxxxxx\n");
+
+	return proc_dointvec(table, write, buffer, lenp, ppos);
+}
+
 static struct ctl_table kern_table[];
 static struct ctl_table vm_table[];
 static struct ctl_table fs_table[];
@@ -1235,7 +1246,7 @@ static struct ctl_table vm_table[] = {
 		.data		= &sysctl_oom_kill_allocating_task,
 		.maxlen		= sizeof(sysctl_oom_kill_allocating_task),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_oom_kill_allocating_tasks,
 	},
 	{
 		.procname	= "oom_dump_tasks",
-- 
2.13.5