mm, oom: reintroduce /proc/pid/oom_adj
This is mostly a revert of 01dc52ebdf47 ("oom: remove deprecated oom_adj")
from Davidlohr Bueso.
It reintroduces /proc/pid/oom_adj for backwards compatibility with earlier
kernels. It simply scales the value linearly when /proc/pid/oom_score_adj
is written.
The major difference is that its scheduled removal is no longer included
in Documentation/feature-removal-schedule.txt. We do warn users with a
single printk, though, to suggest the more powerful and supported
/proc/pid/oom_score_adj interface.
Reported-by: Artem S. Tashkinov <t.artem@lycos.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/uapi/linux/oom.h b/include/uapi/linux/oom.h
index a49c4af..b29272d 100644
--- a/include/uapi/linux/oom.h
+++ b/include/uapi/linux/oom.h
@@ -8,4 +8,13 @@
#define OOM_SCORE_ADJ_MIN (-1000)
#define OOM_SCORE_ADJ_MAX 1000
+/*
+ * /proc/<pid>/oom_adj set to -17 protects from the oom killer for legacy
+ * purposes.
+ */
+#define OOM_DISABLE (-17)
+/* inclusive */
+#define OOM_ADJUST_MIN (-16)
+#define OOM_ADJUST_MAX 15
+
#endif /* _UAPI__INCLUDE_LINUX_OOM_H */