---

yaml
---
r: 94036
b: refs/heads/master
c: a6020ed
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: aab0b1029f0843756b68e0ed3ca983685bf43ed6
+refs/heads/master: a6020ed759404372e8be2b276e85e51735472cc9

trunk/include/linux/mm.h

@@ -172,7 +172,25 @@ struct vm_operations_struct {
 	 * writable, if an error is returned it will cause a SIGBUS */
 	int (*page_mkwrite)(struct vm_area_struct *vma, struct page *page);
 #ifdef CONFIG_NUMA
+	/*
+	 * set_policy() op must add a reference to any non-NULL @new mempolicy
+	 * to hold the policy upon return.  Caller should pass NULL @new to
+	 * remove a policy and fall back to surrounding context--i.e. do not
+	 * install a MPOL_DEFAULT policy, nor the task or system default
+	 * mempolicy.
+	 */
 	int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new);
+
+	/*
+	 * get_policy() op must add reference [mpol_get()] to any policy at
+	 * (vma,addr) marked as MPOL_SHARED.  The shared policy infrastructure
+	 * in mm/mempolicy.c will do this automatically.
+	 * get_policy() must NOT add a ref if the policy at (vma,addr) is not
+	 * marked as MPOL_SHARED. vma policies are protected by the mmap_sem.
+	 * If no [shared/vma] mempolicy exists at the addr, get_policy() op
+	 * must return NULL--i.e., do not "fallback" to task or system default
+	 * policy.
+	 */
 	struct mempolicy *(*get_policy)(struct vm_area_struct *vma,
 					unsigned long addr);
 	int (*migrate)(struct vm_area_struct *vma, const nodemask_t *from,