On Sat, 3 Feb 2007, Arjan van de Ven wrote:
> Well.. That's the point! Only IF there is a reclaim scan do you move
> them out again. The fact that these pages are on the list isn't a
> problem. The fact that you keep encountering them over and over again
> during *scanning* is. So Andrews suggestion makes them go away in the
> situations that actually matter
In order to get this to work try_to_unmap() must be able to distinguish
betwen failures due to MLOCK and otherwise. So I guess we need this patch:
[PATCH] Make try_to_unmap() return SWAP_MLOCK for mlocked pages
Modify try_to_unmap() so that we can distinguish between failing to
unmap because a page is mlocked from other causes.
Signed-off-by: Christoph Lameter <[email protected]>
Index: current/include/linux/rmap.h
===================================================================
--- current.orig/include/linux/rmap.h 2007-02-03 10:24:47.000000000 -0800
+++ current/include/linux/rmap.h 2007-02-03 10:25:08.000000000 -0800
@@ -134,5 +134,6 @@ static inline int page_mkclean(struct pa
#define SWAP_SUCCESS 0
#define SWAP_AGAIN 1
#define SWAP_FAIL 2
+#define SWAP_MLOCK 3
#endif /* _LINUX_RMAP_H */
Index: current/mm/rmap.c
===================================================================
--- current.orig/mm/rmap.c 2007-02-03 10:24:47.000000000 -0800
+++ current/mm/rmap.c 2007-02-03 10:25:08.000000000 -0800
@@ -631,10 +631,16 @@ static int try_to_unmap_one(struct page
* If it's recently referenced (perhaps page_referenced
* skipped over this mm) then we should reactivate it.
*/
- if (!migration && ((vma->vm_flags & VM_LOCKED) ||
- (ptep_clear_flush_young(vma, address, pte)))) {
- ret = SWAP_FAIL;
- goto out_unmap;
+ if (!migration) {
+ if (vma->vm_flags & VM_LOCKED) {
+ ret = SWAP_MLOCK;
+ goto out_unmap;
+ }
+
+ if (ptep_clear_flush_young(vma, address, pte)) {
+ ret = SWAP_FAIL;
+ goto out_unmap;
+ }
}
/* Nuke the page table entry. */
@@ -799,7 +805,8 @@ static int try_to_unmap_anon(struct page
list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
ret = try_to_unmap_one(page, vma, migration);
- if (ret == SWAP_FAIL || !page_mapped(page))
+ if (ret == SWAP_FAIL || ret == SWAP_MLOCK ||
+ !page_mapped(page))
break;
}
spin_unlock(&anon_vma->lock);
@@ -830,7 +837,8 @@ static int try_to_unmap_file(struct page
spin_lock(&mapping->i_mmap_lock);
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
ret = try_to_unmap_one(page, vma, migration);
- if (ret == SWAP_FAIL || !page_mapped(page))
+ if (ret == SWAP_FAIL || ret == SWAP_MLOCK ||
+ !page_mapped(page))
goto out;
}
@@ -913,6 +921,7 @@ out:
* SWAP_SUCCESS - we succeeded in removing all mappings
* SWAP_AGAIN - we missed a mapping, try again later
* SWAP_FAIL - the page is unswappable
+ * SWAP_MLOCK - the page is under mlock()
*/
int try_to_unmap(struct page *page, int migration)
{
Index: current/mm/vmscan.c
===================================================================
--- current.orig/mm/vmscan.c 2007-02-03 10:25:00.000000000 -0800
+++ current/mm/vmscan.c 2007-02-03 10:25:12.000000000 -0800
@@ -516,6 +516,7 @@ static unsigned long shrink_page_list(st
if (page_mapped(page) && mapping) {
switch (try_to_unmap(page, 0)) {
case SWAP_FAIL:
+ case SWAP_MLOCK:
goto activate_locked;
case SWAP_AGAIN:
goto keep_locked;
-
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