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authorDavid Rientjes <rientjes@google.com>2010-08-09 17:19:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-09 20:45:02 -0700
commit51b1bd2ace1595b72956224deda349efa880b693 (patch)
tree82732bb33d26379c05494dcdba8ea390ae0621db
parenta63d83f427fbce97a6cea0db2e64b0eb8435cd10 (diff)
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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>
-rw-r--r--Documentation/feature-removal-schedule.txt25
-rw-r--r--Documentation/filesystems/proc.txt3
-rw-r--r--fs/proc/base.c8
-rw-r--r--include/linux/oom.h3
4 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 71f0fea1058..56cee4727b1 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -151,6 +151,31 @@ Who: Eric Biederman <ebiederm@xmission.com>
---------------------------
+What: /proc/<pid>/oom_adj
+When: August 2012
+Why: /proc/<pid>/oom_adj allows userspace to influence the oom killer's
+ badness heuristic used to determine which task to kill when the kernel
+ is out of memory.
+
+ The badness heuristic has since been rewritten since the introduction of
+ this tunable such that its meaning is deprecated. The value was
+ implemented as a bitshift on a score generated by the badness()
+ function that did not have any precise units of measure. With the
+ rewrite, the score is given as a proportion of available memory to the
+ task allocating pages, so using a bitshift which grows the score
+ exponentially is, thus, impossible to tune with fine granularity.
+
+ A much more powerful interface, /proc/<pid>/oom_score_adj, was
+ introduced with the oom killer rewrite that allows users to increase or
+ decrease the badness() score linearly. This interface will replace
+ /proc/<pid>/oom_adj.
+
+ A warning will be emitted to the kernel log if an application uses this
+ deprecated interface. After it is printed once, future warnings will be
+ suppressed until the kernel is rebooted.
+
+---------------------------
+
What: remove EXPORT_SYMBOL(kernel_thread)
When: August 2006
Files: arch/*/kernel/*_ksyms.c
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index cf1295c2bb6..a6aca874088 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -1285,6 +1285,9 @@ scaled linearly with /proc/<pid>/oom_score_adj.
Writing to /proc/<pid>/oom_score_adj or /proc/<pid>/oom_adj will change the
other with its scaled value.
+NOTICE: /proc/<pid>/oom_adj is deprecated and will be removed, please see
+Documentation/feature-removal-schedule.txt.
+
Caveat: when a parent task is selected, the oom killer will sacrifice any first
generation children with seperate address spaces instead, if possible. This
avoids servers and important system daemons from being killed and loses the
diff --git a/fs/proc/base.c b/fs/proc/base.c
index f923b728388..69254a365ce 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
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 73b8d7b6dd1..f209b683e11 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -2,6 +2,9 @@
#define __INCLUDE_LINUX_OOM_H
/*
+ * /proc/<pid>/oom_adj is deprecated, see
+ * Documentation/feature-removal-schedule.txt.
+ *
* /proc/<pid>/oom_adj set to -17 protects from the oom-killer
*/
#define OOM_DISABLE (-17)