[PATCH 09/19] mm: mempolicy: Make MPOL_LOCAL a real policy

[Mel Gorman]

From: Peter Zijlstra <a.p.zijls...@chello.nl>

Make MPOL_LOCAL a real and exposed policy such that applications that
relied on the previous default behaviour can explicitly request it.

Requested-by: Christoph Lameter <c...@linux.com>
Reviewed-by: Rik van Riel <r...@redhat.com>
Cc: Lee Schermerhorn <lee.schermerh...@hp.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijls...@chello.nl>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Mel Gorman <mgor...@suse.de>
---
 include/uapi/linux/mempolicy.h |    1 +
 mm/mempolicy.c                 |    9 ++++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h
index 23e62e0..3e835c9 100644
--- a/include/uapi/linux/mempolicy.h
+++ b/include/uapi/linux/mempolicy.h
@@ -20,6 +20,7 @@ enum {
        MPOL_PREFERRED,
        MPOL_BIND,
        MPOL_INTERLEAVE,
+       MPOL_LOCAL,
        MPOL_MAX,       /* always last member of enum */
 };
 
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 66e90ec..54bd3e5 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -269,6 +269,10 @@ static struct mempolicy *mpol_new(unsigned short mode, 
unsigned short flags,
                             (flags & MPOL_F_RELATIVE_NODES)))
                                return ERR_PTR(-EINVAL);
                }
+       } else if (mode == MPOL_LOCAL) {
+               if (!nodes_empty(*nodes))
+                       return ERR_PTR(-EINVAL);
+               mode = MPOL_PREFERRED;
        } else if (nodes_empty(*nodes))
                return ERR_PTR(-EINVAL);
        policy = kmem_cache_alloc(policy_cache, GFP_KERNEL);
@@ -2399,7 +2403,6 @@ void numa_default_policy(void)
  * "local" is pseudo-policy:  MPOL_PREFERRED with MPOL_F_LOCAL flag
  * Used only for mpol_parse_str() and mpol_to_str()
  */
-#define MPOL_LOCAL MPOL_MAX
 static const char * const policy_modes[] =
 {
        [MPOL_DEFAULT]    = "default",
@@ -2452,12 +2455,12 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, 
int no_context)
        if (flags)
                *flags++ = '\0';        /* terminate mode string */
 
-       for (mode = 0; mode <= MPOL_LOCAL; mode++) {
+       for (mode = 0; mode < MPOL_MAX; mode++) {
                if (!strcmp(str, policy_modes[mode])) {
                        break;
                }
        }
-       if (mode > MPOL_LOCAL)
+       if (mode >= MPOL_MAX)
                goto out;
 
        switch (mode) {
-- 
1.7.9.2

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