The patch titled
Subject: ksm: set anon_vma of first rmap_item of ksm page to page's anon_vma other than vma's anon_vma
has been added to the -mm tree. Its filename is
ksm-set-anon_vma-of-first-rmap_item-of-ksm-page-to-pages-anon_vma-other-than-vmas-anon_vma.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ksm-set-anon_vma-of-first-rmap_item-of-ksm-page-to-pages-anon_vma-other-than-vmas-anon_vma.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ksm-set-anon_vma-of-first-rmap_item-of-ksm-page-to-pages-anon_vma-other-than-vmas-anon_vma.patch
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------------------------------------------------------
From: z00281421 <z00281421@xxxxxxxxxxxxxxxxxxxx>
Subject: ksm: set anon_vma of first rmap_item of ksm page to page's anon_vma other than vma's anon_vma
Set anon_vma of first rmap_item of ksm page to page's anon_vma other than
vma's anon_vma so that we can lookup all the forked vma of kpage via
reserve map. thus we can try_to_unmap ksm page completely and reclaim or
migrate the ksm page successfully and need not to merg other forked vma
addresses of ksm page with building a rmap_item for it ever after.
A forked more mapcount ksm page with partially merged vma addresses and a
ksm page mapped into non-VM_MERGEABLE vma due to setting MADV_MERGEABLE on
one of the forked vma can be unmapped completely by try_to_unmap.
Link: http://lkml.kernel.org/r/1466688834-127613-1-git-send-email-zhouxianrong@xxxxxxxxxx
Signed-off-by: z00281421 <z00281421@xxxxxxxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Zhou Chengming <zhouchengming1@xxxxxxxxxx>
Cc: Geliang Tang <geliangtang@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff -puN mm/ksm.c~ksm-set-anon_vma-of-first-rmap_item-of-ksm-page-to-pages-anon_vma-other-than-vmas-anon_vma mm/ksm.c
--- a/mm/ksm.c~ksm-set-anon_vma-of-first-rmap_item-of-ksm-page-to-pages-anon_vma-other-than-vmas-anon_vma
+++ a/mm/ksm.c
@@ -970,11 +970,13 @@ out:
* @page: the PageAnon page that we want to replace with kpage
* @kpage: the PageKsm page that we want to map instead of page,
* or NULL the first time when we want to use page as kpage.
+ * @anon_vma: output the anon_vma of page used as kpage
*
* This function returns 0 if the pages were merged, -EFAULT otherwise.
*/
static int try_to_merge_one_page(struct vm_area_struct *vma,
- struct page *page, struct page *kpage)
+ struct page *page, struct page *kpage,
+ struct anon_vma **anon_vma)
{
pte_t orig_pte = __pte(0);
int err = -EFAULT;
@@ -1014,6 +1016,8 @@ static int try_to_merge_one_page(struct
* PageAnon+anon_vma to PageKsm+NULL stable_node:
* stable_tree_insert() will update stable_node.
*/
+ if (anon_vma != NULL)
+ *anon_vma = page_anon_vma(page);
set_page_stable_node(page, NULL);
mark_page_accessed(page);
/*
@@ -1054,6 +1058,7 @@ static int try_to_merge_with_ksm_page(st
{
struct mm_struct *mm = rmap_item->mm;
struct vm_area_struct *vma;
+ struct anon_vma *anon_vma = NULL;
int err = -EFAULT;
down_read(&mm->mmap_sem);
@@ -1061,7 +1066,7 @@ static int try_to_merge_with_ksm_page(st
if (!vma)
goto out;
- err = try_to_merge_one_page(vma, page, kpage);
+ err = try_to_merge_one_page(vma, page, kpage, &anon_vma);
if (err)
goto out;
@@ -1069,7 +1074,10 @@ static int try_to_merge_with_ksm_page(st
remove_rmap_item_from_tree(rmap_item);
/* Must get reference to anon_vma while still holding mmap_sem */
- rmap_item->anon_vma = vma->anon_vma;
+ if (anon_vma != NULL)
+ rmap_item->anon_vma = anon_vma;
+ else
+ rmap_item->anon_vma = vma->anon_vma;
get_anon_vma(vma->anon_vma);
out:
up_read(&mm->mmap_sem);
@@ -1434,6 +1442,11 @@ static void cmp_and_merge_page(struct pa
remove_rmap_item_from_tree(rmap_item);
+ if (kpage == page) {
+ put_page(kpage);
+ return;
+ }
+
if (kpage) {
err = try_to_merge_with_ksm_page(rmap_item, page, kpage);
if (!err) {
_
Patches currently in -mm which might be from z00281421@xxxxxxxxxxxxxxxxxxxx are
ksm-set-anon_vma-of-first-rmap_item-of-ksm-page-to-pages-anon_vma-other-than-vmas-anon_vma.patch
--
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