Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Vicente Bergas <vicencb@gmail.com>
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     <linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: =?iso-8859-1?Q?d=5Flookup:_Unable_to_handle_kernel_paging_request?=
Date:   Sat, 25 May 2019 00:21:11 +0200
MIME-Version: 1.0
Message-ID: <b1f6ba08-6774-4be9-9e96-563f95e9ccdf@gmail.com>
In-Reply-To: <20190522162945.GN17978@ZenIV.linux.org.uk>
References: <23950bcb-81b0-4e07-8dc8-8740eb53d7fd@gmail.com>
 <20190522135331.GM17978@ZenIV.linux.org.uk>
 <bdc8b245-afca-4662-99e2-a082f25fc927@gmail.com>
 <20190522162945.GN17978@ZenIV.linux.org.uk>
User-Agent: Trojita
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wednesday, May 22, 2019 6:29:46 PM CEST, Al Viro wrote:
> On Wed, May 22, 2019 at 05:44:30PM +0200, Vicente Bergas wrote:
> ...
> IOW, here we have also run into bogus hlist forward pointer or head -
> same 0x1000000 in one case and 0x0000880001000000 in two others.
>
> Have you tried to see if KASAN catches anything on those loads?
> Use-after-free, for example...  Another thing to try: slap
> =09WARN_ON(entry->d_flags & DCACHE_NORCU);
> in __d_rehash() and see if it triggers.

Hi,
i have been running 3 days with KASAN enabled and also with
diff a/fs/dcache.c b/fs/dcache.c
@@ -2395,3 +2395,4 @@ static void __d_rehash(struct dentry *entry)
 =09struct hlist_bl_head *b =3D d_hash(entry->d_name.hash);
=20
+=09WARN_ON(entry->d_flags & DCACHE_NORCU);
 =09hlist_bl_lock(b);
but the issue has not appeared again.
Next week i will try -rc2 without KASAN and with WARN_ON and see if it
triggers.

Regards,
  Vicen=C3=A7.