This is a note to let you know that I've just added the patch titled
ksm: fix unlocked iteration over vmas in cmp_and_merge_page()
to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ksm-fix-unlocked-iteration-over-vmas-in-cmp_and_merge_page.patch
and it can be found in the queue-4.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4b22927f0cbd58303aac689e378d20bf56267a39 Mon Sep 17 00:00:00 2001
From: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Date: Tue, 3 Oct 2017 16:14:27 -0700
Subject: ksm: fix unlocked iteration over vmas in cmp_and_merge_page()
From: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
commit 4b22927f0cbd58303aac689e378d20bf56267a39 upstream.
In this place mm is unlocked, so vmas or list may change. Down read
mmap_sem to protect them from modifications.
Link: http://lkml.kernel.org/r/150512788393.10691.8868381099691121308.stgit@localhost.localdomain
Fixes: e86c59b1b12d ("mm/ksm: improve deduplication of zero pages with colouring")
Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: zhong jiang <zhongjiang@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1990,6 +1990,7 @@ static void stable_tree_append(struct rm
*/
static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
{
+ struct mm_struct *mm = rmap_item->mm;
struct rmap_item *tree_rmap_item;
struct page *tree_page = NULL;
struct stable_node *stable_node;
@@ -2062,9 +2063,11 @@ static void cmp_and_merge_page(struct pa
if (ksm_use_zero_pages && (checksum == zero_checksum)) {
struct vm_area_struct *vma;
- vma = find_mergeable_vma(rmap_item->mm, rmap_item->address);
+ down_read(&mm->mmap_sem);
+ vma = find_mergeable_vma(mm, rmap_item->address);
err = try_to_merge_one_page(vma, page,
ZERO_PAGE(rmap_item->address));
+ up_read(&mm->mmap_sem);
/*
* In case of failure, the page was not really empty, so we
* need to continue. Otherwise we're done.
Patches currently in stable-queue which might be from ktkhai@xxxxxxxxxxxxx are
queue-4.13/ksm-fix-unlocked-iteration-over-vmas-in-cmp_and_merge_page.patch