On 12/17/2013 01:55 AM, Wanpeng Li wrote:
Hi Sasha,
On Tue, Dec 17, 2013 at 01:46:42AM -0500, Sasha Levin wrote:
On 12/17/2013 01:11 AM, Naoya Horiguchi wrote:
Hello Bob,
On Tue, Dec 17, 2013 at 12:38:49PM +0800, Bob Liu wrote:
On 12/17/2013 09:10 AM, Sasha Levin wrote:
On 12/16/2013 07:44 PM, Bob Liu wrote:
On 12/16/2013 07:37 AM, Sasha Levin wrote:
Hi all,
While fuzzing with trinity inside a KVM tools guest running latest -next
kernel, I've
stumbled on the following spew.
This seems to be due to commit 0bf598d863e "mbind: add BUG_ON(!vma) in
new_vma_page()"
which added that BUG_ON.
Could you take a try with this patch from Wanpeng Li?
Thanks,
-Bob
Subject: [PATCH] mm/mempolicy: fix !vma in new_vma_page()
....
Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
index eca4a31..73b5a35 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1197,14 +1197,16 @@ static struct page *new_vma_page(struct page
*page, unsigned long private, int *
break;
vma = vma->vm_next;
}
+
+ if (PageHuge(page)) {
+ if (vma)
+ return alloc_huge_page_noerr(vma, address, 1);
+ else
+ return NULL;
+ }
/*
- * queue_pages_range() confirms that @page belongs to some vma,
- * so vma shouldn't be NULL.
+ * if !vma, alloc_page_vma() will use task or system default policy
*/
- BUG_ON(!vma);
-
- if (PageHuge(page))
- return alloc_huge_page_noerr(vma, address, 1);
return alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
}
#else
Hmm... So in essence it's mostly a revert of Naoya's patch, who seemed
pretty certain that this
situation shouldn't happen at all. What's the reasoning behind just
I think this assumption may not correct.
Even if
address = __vma_address(page, vma);
and
vma->start < address < vma->end;
page_address_in_vma() may still return -EFAULT because of many other
conditions in it.
As a result the while loop in new_vma_page() may end with vma=NULL.
Naoya, any idea?
Yes, you totally make sense. So please apply Wanpeng's patch.
Shouldn't it just be a revert of Naoya's patch? Otherwise we're
changing code paths unnecessarily.
Actually, the original target of Naoya's patch is try to fix potential dereference
NULL pointer by Dan. http://marc.info/?l=linux-mm&m=137689530323257&w=2
This patch fix both the regression and potential dereference NULL pointer reported
by Dan. http://marc.info/?l=linux-kernel&m=138726268626705&w=2
Makes sense, thanks!
Thanks,
Sasha
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