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authorLee Schermerhorn <lee.schermerhorn@hp.com>2008-04-28 05:13:14 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-28 11:58:24 -0400
commita6020ed759404372e8be2b276e85e51735472cc9 (patch)
tree1fb0a346909dcc9d3b916671001af87b17931ddd /include
parentaab0b1029f0843756b68e0ed3ca983685bf43ed6 (diff)
mempolicy: document {set|get}_policy() vm_ops APIs
Document mempolicy return value reference semantics assumed by the rest of the mempolicy code for the set_ and get_policy vm_ops in <linux/mm.h>--where the prototypes are defined--to inform any future mempolicy vm_op writers what the rest of the subsystem expects of them. 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>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mm.h18
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bc0ad24cf8c..8b7f4a5d4f6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -172,7 +172,25 @@ struct vm_operations_struct {
172 * writable, if an error is returned it will cause a SIGBUS */ 172 * writable, if an error is returned it will cause a SIGBUS */
173 int (*page_mkwrite)(struct vm_area_struct *vma, struct page *page); 173 int (*page_mkwrite)(struct vm_area_struct *vma, struct page *page);
174#ifdef CONFIG_NUMA 174#ifdef CONFIG_NUMA
175 /*
176 * set_policy() op must add a reference to any non-NULL @new mempolicy
177 * to hold the policy upon return. Caller should pass NULL @new to
178 * remove a policy and fall back to surrounding context--i.e. do not
179 * install a MPOL_DEFAULT policy, nor the task or system default
180 * mempolicy.
181 */
175 int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new); 182 int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new);
183
184 /*
185 * get_policy() op must add reference [mpol_get()] to any policy at
186 * (vma,addr) marked as MPOL_SHARED. The shared policy infrastructure
187 * in mm/mempolicy.c will do this automatically.
188 * get_policy() must NOT add a ref if the policy at (vma,addr) is not
189 * marked as MPOL_SHARED. vma policies are protected by the mmap_sem.
190 * If no [shared/vma] mempolicy exists at the addr, get_policy() op
191 * must return NULL--i.e., do not "fallback" to task or system default
192 * policy.
193 */
176 struct mempolicy *(*get_policy)(struct vm_area_struct *vma, 194 struct mempolicy *(*get_policy)(struct vm_area_struct *vma,
177 unsigned long addr); 195 unsigned long addr);
178 int (*migrate)(struct vm_area_struct *vma, const nodemask_t *from, 196 int (*migrate)(struct vm_area_struct *vma, const nodemask_t *from,