[dpdk-dev] [PATCH] mem: fix undefined behavior in NUMA code

[Anatoly Burakov]

When NUMA-aware hugepages config option is set, we rely on
libnuma to tell the kernel to allocate hugepages on a specific
NUMA node. However, we allocate node mask before we check if
NUMA is available in the first place, which, according to
the manpage [1], causes undefined behaviour.

Fix by only using nodemask when we have NUMA available.

[1] https://linux.die.net/man/3/numa_alloc_onnode

Bugzilla ID: 20

Fixes: 1b72605d2416 ("mem: balanced allocation of hugepages")
Cc: i.maxim...@samsung.com
Cc: sta...@dpdk.org

Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
---
 lib/librte_eal/linuxapp/eal/eal_memory.c | 28 ++++++++++++++----------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c 
b/lib/librte_eal/linuxapp/eal/eal_memory.c
index dbf19499e..4976eeacd 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -263,7 +263,7 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, struct 
hugepage_info *hpi,
        int node_id = -1;
        int essential_prev = 0;
        int oldpolicy;
-       struct bitmask *oldmask = numa_allocate_nodemask();
+       struct bitmask *oldmask = NULL;
        bool have_numa = true;
        unsigned long maxnode = 0;
 
@@ -275,6 +275,7 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, struct 
hugepage_info *hpi,
 
        if (have_numa) {
                RTE_LOG(DEBUG, EAL, "Trying to obtain current memory 
policy.\n");
+               oldmask = numa_allocate_nodemask();
                if (get_mempolicy(&oldpolicy, oldmask->maskp,
                                  oldmask->size + 1, 0, 0) < 0) {
                        RTE_LOG(ERR, EAL,
@@ -390,19 +391,22 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, 
struct hugepage_info *hpi,
 
 out:
 #ifdef RTE_EAL_NUMA_AWARE_HUGEPAGES
-       if (maxnode) {
-               RTE_LOG(DEBUG, EAL,
-                       "Restoring previous memory policy: %d\n", oldpolicy);
-               if (oldpolicy == MPOL_DEFAULT) {
-                       numa_set_localalloc();
-               } else if (set_mempolicy(oldpolicy, oldmask->maskp,
-                                        oldmask->size + 1) < 0) {
-                       RTE_LOG(ERR, EAL, "Failed to restore mempolicy: %s\n",
-                               strerror(errno));
-                       numa_set_localalloc();
+       if (have_numa) {
+               if (maxnode) {
+                       RTE_LOG(DEBUG, EAL,
+                               "Restoring previous memory policy: %d\n",
+                                       oldpolicy);
+                       if (oldpolicy == MPOL_DEFAULT) {
+                               numa_set_localalloc();
+                       } else if (set_mempolicy(oldpolicy, oldmask->maskp,
+                                                oldmask->size + 1) < 0) {
+                               RTE_LOG(ERR, EAL, "Failed to restore mempolicy: 
%s\n",
+                                       strerror(errno));
+                               numa_set_localalloc();
+                       }
                }
+               numa_free_cpumask(oldmask);
        }
-       numa_free_cpumask(oldmask);
 #endif
        return i;
 }
-- 
2.17.1