diff options
| author | Lee Schermerhorn <lee.schermerhorn@hp.com> | 2008-04-28 02:13:14 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-28 08:58:24 -0700 |
| commit | a6020ed759404372e8be2b276e85e51735472cc9 (patch) | |
| tree | 1fb0a346909dcc9d3b916671001af87b17931ddd /include/linux/mm.h | |
| parent | aab0b1029f0843756b68e0ed3ca983685bf43ed6 (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/linux/mm.h')
| -rw-r--r-- | include/linux/mm.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index bc0ad24cf8c0..8b7f4a5d4f6a 100644 --- a/include/linux/mm.h +++ b/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, |