On Sat, Jan 25, 2014 at 07:12:35PM -0800, David Rientjes wrote:
> As a result of commit 5606e3877ad8 ("mm: numa: Migrate on reference
> policy"), /proc/<pid>/numa_maps prints the mempolicy for any <pid> as
> "prefer:N" for the local node, N, of the process reading the file.
>
> This should only be printed when the mempolicy of <pid> is MPOL_PREFERRED
> for node N.
>
> If the process is actually only using the default mempolicy for local node
> allocation, make sure "default" is printed as expected.
>
> Reported-by: Robert Lippert <rlipp...@google.com>
> Signed-off-by: David Rientjes <rient...@google.com>
Hmm, it is using a preferred policy but I see your point as expectations
of an application parsing numa_maps have been broken. The patch makes
non-obvious assumptions about how and when MPOL_F_MORON gets set which
could change in the future and be missed. Use this instead? It might need
to be changed again if there is a need to control whether automatic numa
balancing can be enabled or disabled on a per-process basis.
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c2ccec0..c1a2573 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -120,6 +120,14 @@ static struct mempolicy default_policy = {
static struct mempolicy preferred_node_policy[MAX_NUMNODES];
+/* Returns true if the policy is the default policy */
+static bool mpol_is_default(struct mempolicy *pol)
+{
+ return !pol ||
+ pol == &default_policy ||
+ pol == &preferred_node_policy[numa_node_id()];
+}
+
static struct mempolicy *get_task_policy(struct task_struct *p)
{
struct mempolicy *pol = p->mempolicy;
@@ -2856,7 +2864,7 @@ void mpol_to_str(char *buffer, int maxlen, struct
mempolicy *pol)
unsigned short mode = MPOL_DEFAULT;
unsigned short flags = 0;
- if (pol && pol != &default_policy) {
+ if (!mpol_is_default(pol)) {
mode = pol->mode;
flags = pol->flags;
}
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