multipath: add support for setting oom_score_adj

The oom_adj procfs interface is deprecated. I've added support for using the
new oom_score_adj interface.  The code still falls back to using oom_adj
if oom_score_adj doesn't exist.

Resending, since I was obviously working far too late last night.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>

diff --git a/multipathd/main.c b/multipathd/main.c
index 68ce749..5038d67 100644 (file)
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -15,6 +15,7 @@
 #include <sys/time.h>
 #include <sys/resource.h>
 #include <limits.h>
+#include <linux/oom.h>
 
 /*
  * libcheckers
@@ -1458,17 +1459,35 @@ setscheduler (void)
 }
 
 static void
-set_oom_adj (int val)
+set_oom_adj (void)
 {
+       int retry = 1;
+       char *file = "/proc/self/oom_score_adj";
+       int score = OOM_SCORE_ADJ_MIN;
        FILE *fp;
+       struct stat st;
 
-       fp = fopen("/proc/self/oom_adj", "w");
-
-       if (!fp)
-               return;
-
-       fprintf(fp, "%i", val);
-       fclose(fp);
+       do {
+               if (stat(file, &st) == 0){
+                       fp = fopen(file, "w");
+                       if (!fp) {
+                               condlog(0, "couldn't fopen %s : %s", file,
+                                       strerror(errno));
+                               return;
+                       }
+                       fprintf(fp, "%i", score);
+                       fclose(fp);
+                       return;
+               }
+               if (errno != ENOENT) {
+                       condlog(0, "couldn't stat %s : %s", file,
+                               strerror(errno));
+                       return;
+               }
+               file = "/proc/self/oom_adj";
+               score = OOM_ADJUST_MIN;
+       } while (retry--);
+       condlog(0, "couldn't adjust oom score");
 }
 
 static int
@@ -1547,7 +1566,7 @@ child (void * param)
 
        signal_init();
        setscheduler();
-       set_oom_adj(-16);
+       set_oom_adj();
        vecs = gvecs = init_vecs();
 
        if (!vecs)