From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f178.google.com (mail-wi0-f178.google.com [209.85.212.178]) by kanga.kvack.org (Postfix) with ESMTP id 10CC16B00F0 for ; Thu, 12 Jun 2014 09:29:36 -0400 (EDT) Received: by mail-wi0-f178.google.com with SMTP id n15so2956846wiw.5 for ; Thu, 12 Jun 2014 06:29:36 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id s1si27060063wiw.15.2014.06.12.06.29.34 for ; Thu, 12 Jun 2014 06:29:35 -0700 (PDT) Message-ID: <5399ab3f.814db40a.0ca2.ffffc952SMTPIN_ADDED_BROKEN@mx.google.com> From: Naoya Horiguchi Subject: Re: kmemleak: Unable to handle kernel paging request Date: Thu, 12 Jun 2014 09:29:15 -0400 In-Reply-To: References: <20140611173851.GA5556@MacBook-Pro.local> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Denis Kirjanov Cc: Catalin Marinas , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton Hi Denis, On Thu, Jun 12, 2014 at 04:00:57PM +0400, Denis Kirjanov wrote: > On 6/12/14, Denis Kirjanov wrote: > > On 6/12/14, Catalin Marinas wrote: > >> On 11 Jun 2014, at 21:04, Denis Kirjanov wro= te: > >>> On 6/11/14, Catalin Marinas wrote: > >>>> On Wed, Jun 11, 2014 at 04:13:07PM +0400, Denis Kirjanov wrote: > >>>>> I got a trace while running 3.15.0-08556-gdfb9454: > >>>>> > >>>>> [ 104.534026] Unable to handle kernel paging request for data at= > >>>>> address 0xc00000007f000000 > >>>> > >>>> Were there any kmemleak messages prior to this, like "kmemleak > >>>> disabled"? There could be a race when kmemleak is disabled because= of > >>>> some fatal (for kmemleak) error while the scanning is taking place= > >>>> (which needs some more thinking to fix properly). > >>> > >>> No. I checked for the similar problem and didn't find anything rele= vant. > >>> I'll try to bisect it. > >> > >> Does this happen soon after boot? I guess it=E2=80=99s the first sca= n > >> (scheduled at around 1min after boot). Something seems to be telling= > >> kmemleak that there is a valid memory block at 0xc00000007f000000. > > > > Yeah, it happens after a while with a booted system so that's the > > first kmemleak scan. > > > >> Catalin > > > = > I've bisected to this commit: d4c54919ed86302094c0ca7d48a8cbd4ee753e92 > "mm: add !pte_present() check on existing hugetlb_entry callbacks". > Reverting the commit fixes the issue Thanks for the effort of bisecting. I guess that this bug happens because pte_none() check was gone in this commit, so could you try to find if the following patch fixes the problem= ? I don't know much about kmemleak's details, so I'm not sure how this bug affected kmemleak. So I'm appreciated if you would add some comment in patch description. Thanks, Naoya Horiguchi --- Date: Thu, 12 Jun 2014 08:56:27 -0400 Subject: [PATCH] mm: revoke pte_none() check for hugetlb_entry() callback= s commit: d4c54919ed86302094c0ca7d48a8cbd4ee753e92 ("mm: add !pte_present()= check on existing hugetlb_entry callbacks") removed pte_none() check in a ->hugetlb_entry() handler, which unexpectedly broke other features like= kmemleak. pte_none() check should be done in common page walk code, because we do so for normal pages and page walk might want to handle holes with ->pte_hole() callback. Reported-by: Denis Kirjanov Signed-off-by: Naoya Horiguchi --- mm/pagewalk.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/pagewalk.c b/mm/pagewalk.c index 2beeabf502c5..0618657285c4 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -118,6 +118,13 @@ static int walk_hugetlb_range(struct vm_area_struct = *vma, do { next =3D hugetlb_entry_end(h, addr, end); pte =3D huge_pte_offset(walk->mm, addr & hmask); + if (huge_pte_none(*pte)) { + if (walk->pte_hole) + err =3D walk->pte_hole(addr, next, walk); + if (err) + break; + continue; + } if (pte && walk->hugetlb_entry) err =3D walk->hugetlb_entry(pte, hmask, addr, next, walk); if (err) -- = 1.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org