linux-kernel - Re: BUG: Bad page state in process true pfn:a8fed on arm

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Message-ID: <20200825174410.1af823db@canb.auug.org.au>
Date:   Tue, 25 Aug 2020 17:44:10 +1000
From:   Stephen Rothwell <sfr@...b.auug.org.au>
To:     Naresh Kamboju <naresh.kamboju@...aro.org>
Cc:     Matthew Wilcox <willy@...radead.org>,
        linux-mm <linux-mm@...ck.org>,
        Linux-Next Mailing List <linux-next@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        lkft-triage@...ts.linaro.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        LTP List <ltp@...ts.linux.it>, Arnd Bergmann <arnd@...db.de>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Christoph Hellwig <hch@....de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Xu <peterx@...hat.com>, opendmb@...il.com,
        Linus Walleij <linus.walleij@...aro.org>,
        afzal.mohd.ma@...il.com, Will Deacon <will@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: BUG: Bad page state in process true pfn:a8fed on arm

Hi all,

On Tue, 25 Aug 2020 13:03:53 +0530 Naresh Kamboju <naresh.kamboju@...aro.org> wrote:
>
> On Mon, 24 Aug 2020 at 16:36, Matthew Wilcox <willy@...radead.org> 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 <naresh.kamboju@...aro.org>
> Reported-by: Anders Roxell <anders.roxell@...aro.org>
> 
> 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 <willy@...radead.org>
> 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

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