oom: deprecate oom_adj tunable

/proc/pid/oom_adj is now deprecated so that that it may eventually be
removed.  The target date for removal is August 2012.

A warning will be printed to the kernel log if a task attempts to use this
interface.  Future warning will be suppressed until the kernel is rebooted
to prevent spamming the kernel log.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index f923b728388a..69254a365ce2 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1037,6 +1037,14 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
                 return -EACCES;
         }
 
+        /*
+         * Warn that /proc/pid/oom_adj is deprecated, see
+         * Documentation/feature-removal-schedule.txt.
+         */
+        printk_once(KERN_WARNING "%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_adj = oom_adjust;
         /*
          * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum