[PATCH] OOM killer meets userspace headers

Despite mm.h is not being exported header, it does contain one thing
which is part of userspace ABI -- value disabling OOM killer for given
process. So,
a) create and export include/linux/oom.h
b) move OOM_DISABLE define there.
c) turn bounding values of /proc/$PID/oom_adj into defines and export
   them too.

Note: mass __KERNEL__ removal will be done later.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/proc/base.c

@@ -72,6 +72,7 @@
 #include <linux/audit.h>
 #include <linux/poll.h>
 #include <linux/nsproxy.h>
+#include <linux/oom.h>
 #include "internal.h"
 
 /* NOTE:
@@ -689,7 +690,8 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
 	if (copy_from_user(buffer, buf, count))
 		return -EFAULT;
 	oom_adjust = simple_strtol(buffer, &end, 0);
-	if ((oom_adjust < -16 || oom_adjust > 15) && oom_adjust != OOM_DISABLE)
+	if ((oom_adjust < OOM_ADJUST_MIN || oom_adjust > OOM_ADJUST_MAX) &&
+	     oom_adjust != OOM_DISABLE)
 		return -EINVAL;
 	if (*end == '\n')
 		end++;

include/linux/Kbuild

@@ -120,6 +120,7 @@ header-y += netrom.h
 header-y += nfs2.h
 header-y += nfs4_mount.h
 header-y += nfs_mount.h
+header-y += oom.h
 header-y += param.h
 header-y += pci_ids.h
 header-y += pci_regs.h

include/linux/mm.h

@@ -1115,9 +1115,6 @@ int in_gate_area_no_task(unsigned long addr);
 #define in_gate_area(task, addr) ({(void)task; in_gate_area_no_task(addr);})
 #endif	/* __HAVE_ARCH_GATE_AREA */
 
-/* /proc/<pid>/oom_adj set to -17 protects from the oom-killer */
-#define OOM_DISABLE -17
-
 int drop_caches_sysctl_handler(struct ctl_table *, int, struct file *,
 					void __user *, size_t *, loff_t *);
 unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,

include/linux/oom.h

@@ -0,0 +1,10 @@
+#ifndef __INCLUDE_LINUX_OOM_H
+#define __INCLUDE_LINUX_OOM_H
+
+/* /proc/<pid>/oom_adj set to -17 protects from the oom-killer */
+#define OOM_DISABLE (-17)
+/* inclusive */
+#define OOM_ADJUST_MIN (-16)
+#define OOM_ADJUST_MAX 15
+
+#endif

mm/oom_kill.c

@@ -15,6 +15,7 @@
  *  kernel subsystems and hints as to where to find out what things do.
  */
 
+#include <linux/oom.h>
 #include <linux/mm.h>
 #include <linux/sched.h>
 #include <linux/swap.h>