[PATCH] oom-killer disable for iscsi/lvm2/multipath userland critical sections

iscsi/lvm2/multipath needs guaranteed protection from the oom-killer, so
make the magical value of -17 in /proc/<pid>/oom_adj defeat the oom-killer
altogether.

(akpm: we still need to document oom_adj and friends in
Documentation/filesystems/proc.txt!)

Signed-off-by: Andrea Arcangeli <andrea@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 5 insertions, 2 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index dad8ea4e00a0..39fd336cfdb9 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -751,7 +751,7 @@ 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)
+        if ((oom_adjust < -16 || oom_adjust > 15) && oom_adjust != OOM_DISABLE)
                 return -EINVAL;
         if (*end == '\n')
                 end++;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6a931374d6c4..85f7d1bea937 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -857,5 +857,8 @@ 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
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 9595a0f6c4b8..4bbb1cb10495 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -145,7 +145,7 @@ static struct task_struct * select_bad_process(void)
         do_posix_clock_monotonic_gettime(&uptime);
         do_each_thread(g, p)
                 /* skip the init task with pid == 1 */
-                if (p->pid > 1) {
+                if (p->pid > 1 && p->oomkilladj != OOM_DISABLE) {
                         unsigned long points;
 
                         /*