gentoo-overlay/sys-process/numad/files/numad-0.5-fix-sparse-node-ids.patch

From ab79ec5b6389507b4970d68862abb95d0b2b94c9 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Jun 17 2019 10:37:48 +0000
Subject: fix sparse node ids


CPU-ids can be sparse due to disabling a subset of CPUs.
On ppc64le this even will make the node_ids sparse, this is actually pretty
common on ppc64 when SMT is disabled.

Numad has the assumption of cpu/node-ids always being linear and due to that
accesses the 'node' array out of bounds. That triggers crashes like the
following:

  Thread 1 "numad" received signal SIGSEGV, Segmentation fault.
  #0 0x00000fb6cd2779f4 in bind_process_and_migrate_memory (p=0xfb6fc1e0f70)
    at numad.c:998
  #1 0x00000fb6cd27d148 in manage_loads () at numad.c:2225
  #2 0x00000fb6cd2734dc in main (argc=<optimized out>, argv=<optimized out>)
    at numad.c:2654

Instead of directly indexing with node_id we need to detect which array
element has the matching node_id and use that.

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>

---

diff --git a/numad.c b/numad.c
index a6a7a5d..524bf61 100644
--- a/numad.c
+++ b/numad.c
@@ -995,7 +995,18 @@ int bind_process_and_migrate_memory(process_data_p p) {
     int node_id = 0;
     while (nodes) {
         if (ID_IS_IN_LIST(node_id, p->node_list_p)) {
-            OR_LISTS(cpu_bind_list_p, cpu_bind_list_p, node[node_id].cpu_list_p);
+            int id = -1;
+            for (int node_ix = 0;  (node_ix < num_nodes);  node_ix++) {
+                if (node[node_ix].node_id == node_id) {
+                    id = node_ix;
+                    break;
+                }
+        }
+            if (id == -1) {
+                numad_log(LOG_CRIT, "Node %d is requested, but unknown\n", node_id);
+                exit(EXIT_FAILURE);
+            }
+            OR_LISTS(cpu_bind_list_p, cpu_bind_list_p, node[id].cpu_list_p);
             nodes -= 1;
         }
         node_id += 1;