oom-kill: fix NUMA constraint check with nodemask

Fix node-oriented allocation handling in oom-kill.c I myself think of this
as a bugfix not as an ehnancement.

In these days, things are changed as
  - alloc_pages() eats nodemask as its arguments, __alloc_pages_nodemask().
  - mempolicy don't maintain its own private zonelists.
  (And cpuset doesn't use nodemask for __alloc_pages_nodemask())

So, current oom-killer's check function is wrong.

This patch does
  - check nodemask, if nodemask && nodemask doesn't cover all
    node_states[N_HIGH_MEMORY], this is CONSTRAINT_MEMORY_POLICY.
  - Scan all zonelist under nodemask, if it hits cpuset's wall
    this faiulre is from cpuset.
And
  - modifies the caller of out_of_memory not to call oom if __GFP_THISNODE.
    This doesn't change "current" behavior. If callers use __GFP_THISNODE
    it should handle "page allocation failure" by itself.

  - handle __GFP_NOFAIL+__GFP_THISNODE path.
    This is something like a FIXME but this gfpmask is not used now.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hioryu@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 33 insertions, 13 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 6bb8a7a7ec9a..25c679e0288a 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -196,27 +196,46 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
 /*
  * Determine the type of allocation constraint.
  */
-static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
-                                                    gfp_t gfp_mask)
-{
 #ifdef CONFIG_NUMA
+static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
+                                    gfp_t gfp_mask, nodemask_t *nodemask)
+{
         struct zone *zone;
         struct zoneref *z;
         enum zone_type high_zoneidx = gfp_zone(gfp_mask);
-        nodemask_t nodes = node_states[N_HIGH_MEMORY];
 
-        for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
-                if (cpuset_zone_allowed_softwall(zone, gfp_mask))
-                        node_clear(zone_to_nid(zone), nodes);
-                else
-                        return CONSTRAINT_CPUSET;
+        /*
+         * Reach here only when __GFP_NOFAIL is used. So, we should avoid
+         * to kill current.We have to random task kill in this case.
+         * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now.
+         */
+        if (gfp_mask & __GFP_THISNODE)
+                return CONSTRAINT_NONE;
 
-        if (!nodes_empty(nodes))
+        /*
+         * The nodemask here is a nodemask passed to alloc_pages(). Now,
+         * cpuset doesn't use this nodemask for its hardwall/softwall/hierarchy
+         * feature. mempolicy is an only user of nodemask here.
+         * check mempolicy's nodemask contains all N_HIGH_MEMORY
+         */
+        if (nodemask && !nodes_subset(node_states[N_HIGH_MEMORY], *nodemask))
                 return CONSTRAINT_MEMORY_POLICY;
-#endif
+
+        /* Check this allocation failure is caused by cpuset's wall function */
+        for_each_zone_zonelist_nodemask(zone, z, zonelist,
+                        high_zoneidx, nodemask)
+                if (!cpuset_zone_allowed_softwall(zone, gfp_mask))
+                        return CONSTRAINT_CPUSET;
 
         return CONSTRAINT_NONE;
 }
+#else
+static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
+                                gfp_t gfp_mask, nodemask_t *nodemask)
+{
+        return CONSTRAINT_NONE;
+}
+#endif
 
 /*
  * Simple selection loop. We chose the process with the highest
@@ -613,7 +632,8 @@ rest_and_return:
  * OR try to be smart about which process to kill. Note that we
  * don't have to be perfect here, we just have to be good.
  */
-void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
+void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
+                int order, nodemask_t *nodemask)
 {
         unsigned long freed = 0;
         enum oom_constraint constraint;
@@ -632,7 +652,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
          * Check if there were limitations on the allocation (only relevant for
          * NUMA) that may require different handling.
          */
-        constraint = constrained_alloc(zonelist, gfp_mask);
+        constraint = constrained_alloc(zonelist, gfp_mask, nodemask);
         read_lock(&tasklist_lock);
 
         switch (constraint) {