[PATCH 1/8] Direct Migration V2: Swap migration patchset fixes

Christoph Lameter
2005-11-08T21:03:11Z

Fixes to swap migration patch V5 (may already be in mm)

- Fix comment for isolate_lru_page() and the check for the result
of __isolate_lru_page in isolate_lru_pages()

- migrate_page_add: check for mapping == NULL

- check_range: Its okay if the first vma has the flag VM_RESERVED set if the
MPOL_MF_DISCONTIG_OK flag was specified by the caller.

- Change the permission check to use comparisons instead of XORs.
Revise the comments.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.14-mm1/mm/vmscan.c
===================================================================
--- linux-2.6.14-mm1.orig/mm/vmscan.c 2005-11-07 11:48:47.000000000 -0800
+++ linux-2.6.14-mm1/mm/vmscan.c 2005-11-08 11:17:13.000000000 -0800
@@ -755,7 +755,7 @@ static int isolate_lru_pages(struct zone
/* Succeeded to isolate page */
list_add(&page->lru, dst);
break;
- case -1:
+ case -ENOENT:
/* Not possible to isolate */
list_move(&page->lru, src);
break;
@@ -782,7 +782,7 @@ static void lru_add_drain_per_cpu(void *
* Result:
* 0 = page not on LRU list
* 1 = page removed from LRU list and added to the specified list.
- * -1 = page is being freed elsewhere.
+ * -ENOENT = page is being freed elsewhere.
*/
int isolate_lru_page(struct page *page)
{
Index: linux-2.6.14-mm1/mm/mempolicy.c
===================================================================
--- linux-2.6.14-mm1.orig/mm/mempolicy.c 2005-11-07 11:48:26.000000000 -0800
+++ linux-2.6.14-mm1/mm/mempolicy.c 2005-11-08 11:16:42.000000000 -0800
@@ -217,6 +217,7 @@ static void migrate_page_add(struct vm_a
* Avoid migrating a page that is shared by others and not writable.
*/
if ((flags & MPOL_MF_MOVE_ALL) ||
+ !page->mapping ||
PageAnon(page) ||
mapping_writably_mapped(page->mapping) ||
single_mm_mapping(vma->vm_mm, page->mapping)
@@ -359,7 +360,8 @@ check_range(struct mm_struct *mm, unsign
first = find_vma(mm, start);
if (!first)
return ERR_PTR(-EFAULT);
- if (first->vm_flags & VM_RESERVED)
+ if (first->vm_flags & VM_RESERVED &&
+ !(flags & MPOL_MF_DISCONTIG_OK))
return ERR_PTR(-EACCES);
prev = NULL;
for (vma = first; vma && vma->vm_start < end; vma = vma->vm_next) {
@@ -790,18 +792,13 @@ asmlinkage long sys_migrate_pages(pid_t
return -EINVAL;

/*
- * We only allow a process to move the pages of another
- * if the process issuing sys_migrate has the right to send a kill
- * signal to the process to be moved. Moving another processes
- * memory may impact the performance of that process. If the
- * process issuing sys_migrate_pages has the right to kill the
- * target process then obviously that process has the right to
- * impact the performance of the target process.
- *
- * The permission check was taken from check_kill_permission()
+ * Check if this process has the right to modify the specified
+ * process. The right exists if the process has administrative
+ * capabilities, superuser priviledges or the same
+ * userid as the target process.
*/
- if ((current->euid ^ task->suid) && (current->euid ^ task->uid) &&
- (current->uid ^ task->suid) && (current->uid ^ task->uid) &&
+ if ((current->euid != task->suid) && (current->euid != task->uid) &&
+ (current->uid != task->suid) && (current->uid != task->uid) &&
!capable(CAP_SYS_ADMIN)) {
err = -EPERM;
goto out;