On Thu, 19 Dec 2013 08:16:35 +0800 Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> wrote:
> page_get_anon_vma() called in page_referenced_anon() will lock and
> increase the refcount of anon_vma, page won't be locked for anonymous
> page. This patch fix it by skip check anonymous page locked.
>
> [ 588.698828] kernel BUG at mm/rmap.c:1663!
Why is all this suddenly happening. Did we change something, or did a
new test get added to trinity?
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1660,7 +1660,8 @@ done:
>
> int rmap_walk(struct page *page, struct rmap_walk_control *rwc)
> {
> - VM_BUG_ON(!PageLocked(page));
> + if (!PageAnon(page) || PageKsm(page))
> + VM_BUG_ON(!PageLocked(page));
>
> if (unlikely(PageKsm(page)))
> return rmap_walk_ksm(page, rwc);
Is there any reason why rmap_walk_ksm() and rmap_walk_file() *need*
PageLocked() whereas rmap_walk_anon() does not? If so, let's implement
it like this:
--- a/mm/rmap.c~a
+++ a/mm/rmap.c
@@ -1716,6 +1716,10 @@ static int rmap_walk_file(struct page *p
struct vm_area_struct *vma;
int ret = SWAP_AGAIN;
+ /*
+ * page must be locked because <reason goes here>
+ */
+ VM_BUG_ON(!PageLocked(page));
if (!mapping)
return ret;
mutex_lock(&mapping->i_mmap_mutex);
@@ -1737,8 +1741,6 @@ static int rmap_walk_file(struct page *p
int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
struct vm_area_struct *, unsigned long, void *), void *arg)
{
- VM_BUG_ON(!PageLocked(page));
-
if (unlikely(PageKsm(page)))
return rmap_walk_ksm(page, rmap_one, arg);
else if (PageAnon(page))
--- a/mm/ksm.c~a
+++ a/mm/ksm.c
@@ -2006,6 +2006,9 @@ int rmap_walk_ksm(struct page *page, int
int search_new_forks = 0;
VM_BUG_ON(!PageKsm(page));
+ /*
+ * page must be locked because <reason goes here>
+ */
VM_BUG_ON(!PageLocked(page));
stable_node = page_stable_node(page);
Or if there is no reason why the page must be locked for
rmap_walk_ksm() and rmap_walk_file(), let's just remove rmap_walk()'s
VM_BUG_ON()? And rmap_walk_ksm()'s as well - it's duplicative anyway.
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