Subject: Re: BUG: Bad page state in process true pfn:a8fed on arm

From: Stephen Rothwell <[email-masked]>
Date: Tue, 25 Aug 2020 17:44:10 +1000

Hi all,

On Tue, 25 Aug 2020 13:03:53 +0530 Naresh Kamboju <[email-masked]> wrote:
>
> On Mon, 24 Aug 2020 at 16:36, Matthew Wilcox <[email-masked]> wrote:
> >
> > On Mon, Aug 24, 2020 at 03:14:55PM +0530, Naresh Kamboju wrote:  
> > > [   67.545247] BUG: Bad page state in process true  pfn:a8fed
> > > [   67.550767] page:9640c0ab refcount:0 mapcount:-1024  
> >
> > Somebody freed a page table without calling __ClearPageTable() on it.  
> 
> After running git bisect on this problem,
> The first suspecting of this problem on arm architecture this patch.
> 424efe723f7717430bec7c93b4d28bba73e31cf6
> ("mm: account PMD tables like PTE tables ")
> 
> Reported-by: Naresh Kamboju <[email-masked]>
> Reported-by: Anders Roxell <[email-masked]>
> 
> Additional information:
> We have tested linux next by reverting this patch and confirmed
> that the reported BUG is not reproduced.
> 
> These configs enabled on the running device,
> 
> CONFIG_TRANSPARENT_HUGEPAGE=y
> CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y
> 
> 
> -- Suspecting patch --
> commit 424efe723f7717430bec7c93b4d28bba73e31cf6
> Author: Matthew Wilcox <[email-masked]>
> Date:   Thu Aug 20 10:01:30 2020 +1000
> 
>     mm: account PMD tables like PTE tables

OK, I have reverted that patch from todays' linux-next.

-- 
Cheers,
Stephen Rothwell