[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>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index dad8ea4e00a03efae08302c41e8951eb84eb811e..39fd336cfdb9ca68c354a22f432e74c63a9bf732 100644 (file)
--- 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 6a931374d6c4975b89cecf5ffa6d6321b9f4eb8a..85f7d1bea937543327890cdd21be0ed967db416c 100644 (file)
--- 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 9595a0f6c4b8891d832f109781d460060fada872..4bbb1cb10495ea486db83868055762888835c8b3 100644 (file)
--- 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;
 
                        /*