mempolicy: rename mpol_free to mpol_put

This is a change that was requested some time ago by Mel Gorman.  Makes sense
to me, so here it is.

Note: I retain the name "mpol_free_shared_policy()" because it actually does
free the shared_policy, which is NOT a reference counted object.  However, ...

The mempolicy object[s] referenced by the shared_policy are reference counted,
so mpol_put() is used to release the reference held by the shared_policy.  The
mempolicy might not be freed at this time, because some task attached to the
shared object associated with the shared policy may be in the process of
allocating a page based on the mempolicy.  In that case, the task performing
the allocation will hold a reference on the mempolicy, obtained via
mpol_shared_policy_lookup().  The mempolicy will be freed when all tasks
holding such a reference have called mpol_put() for the mempolicy.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 177c7a7d2bb3..5326876d814d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1196,7 +1196,7 @@ static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
 	pvma.vm_ops = NULL;
 	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
 	page = swapin_readahead(entry, gfp, &pvma, 0);
-	mpol_free(pvma.vm_policy);
+	mpol_put(pvma.vm_policy);
 	return page;
 }
 
@@ -1212,7 +1212,7 @@ static struct page *shmem_alloc_page(gfp_t gfp,
 	pvma.vm_ops = NULL;
 	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
 	page = alloc_page_vma(gfp, &pvma, 0);
-	mpol_free(pvma.vm_policy);
+	mpol_put(pvma.vm_policy);
 	return page;
 }
 #else /* !CONFIG_NUMA */