From: =?UTF-8?B?VG9yYWxmIEbDtnJzdGVy?= <toralf.foerster@gmx.de>
Subject: Re: [uml-devel] fuzz tested 32 bit user mode linux image hangs in
 radix_tree_next_chunk()
Date: Wed, 06 Nov 2013 22:18:53 +0100
Message-ID: <527AB23D.2060305@gmx.de>
References: <526696BF.6050909@gmx.de>	<CAFLxGvy3NeRKu+KQCCm0j4LS60PYhH0bC8WWjfiPvpstPBjAkA@mail.gmail.com>	<5266A698.10400@gmx.de>	<5266B60A.1000005@nod.at>	<52715AD1.7000703@gmx.de> <CALYGNiPvJF1u8gXNcX1AZR5-VkGqJnaose84KBbdaoBAq8aoGQ@mail.gmail.com>
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Cc: Richard Weinberger <richard@nod.at>,
 Richard Weinberger <richard.weinberger@gmail.com>,
 Linux Kernel <linux-kernel@vger.kernel.org>,
 linux-fsdevel <linux-fsdevel@vger.kernel.org>,
 "linux-mm@kvack.org" <linux-mm@kvack.org>,
 UML devel <user-mode-linux-devel@lists.sourceforge.net>
To: Konstantin Khlebnikov <koct9i@gmail.com>
Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <CALYGNiPvJF1u8gXNcX1AZR5-VkGqJnaose84KBbdaoBAq8aoGQ@mail.gmail.com>
Sender: owner-linux-mm@kvack.org
List-Id: linux-fsdevel.vger.kernel.org

On 11/06/2013 05:06 PM, Konstantin Khlebnikov wrote:
> In this case it must stop after scanning whole tree in line:
> /* Overflow after ~0UL */
> if (!index)
>   return NULL;
>=20

A fresh current example with latest git tree shows that lines 769 and 770=
 do alternate :


tfoerste@n22 ~/devel/linux $ sudo gdb /usr/local/bin/linux-v3.12-48-gbe40=
8cd 16619 -n -batch -ex bt
0x08296a8c in radix_tree_next_chunk (root=3D0x25, iter=3D0x462e7c64, flag=
s=3D12) at lib/radix-tree.c:770
770                                             if (node->slots[offset])
#0  0x08296a8c in radix_tree_next_chunk (root=3D0x25, iter=3D0x462e7c64, =
flags=3D12) at lib/radix-tree.c:770
#1  0x080cc1fe in find_get_pages (mapping=3D0x462ad470, start=3D0, nr_pag=
es=3D14, pages=3D0xc) at mm/filemap.c:844
#2  0x080d5d6a in pagevec_lookup (pvec=3D0x462e7cc8, mapping=3D0x25, star=
t=3D37, nr_pages=3D37) at mm/swap.c:914
#3  0x080d615a in truncate_inode_pages_range (mapping=3D0x462ad470, lstar=
t=3D0, lend=3D-1) at mm/truncate.c:241
#4  0x080d64ff in truncate_inode_pages (mapping=3D0x25, lstart=3D51539607=
589) at mm/truncate.c:358




tfoerste@n22 ~/devel/linux $ sudo gdb /usr/local/bin/linux-v3.12-48-gbe40=
8cd 16619 -n -batch -ex bt
radix_tree_next_chunk (root=3D0x28, iter=3D0x462e7c64, flags=3D18) at lib=
/radix-tree.c:769
769                                     while (++offset < RADIX_TREE_MAP_=
SIZE) {
#0  radix_tree_next_chunk (root=3D0x28, iter=3D0x462e7c64, flags=3D18) at=
 lib/radix-tree.c:769
#1  0x080cc1fe in find_get_pages (mapping=3D0x462ad470, start=3D0, nr_pag=
es=3D14, pages=3D0x12) at mm/filemap.c:844
#2  0x080d5d6a in pagevec_lookup (pvec=3D0x462e7cc8, mapping=3D0x28, star=
t=3D40, nr_pages=3D40) at mm/swap.c:914
#3  0x080d615a in truncate_inode_pages_range (mapping=3D0x462ad470, lstar=
t=3D0, lend=3D-1) at mm/truncate.c:241
#4  0x080d64ff in truncate_inode_pages (mapping=3D0x28, lstart=3D77309411=
368) at mm/truncate.c:358
#5  0x0825e388 in hostfs_evict_inode (inode=3D0x462ad3b8) at fs/hostfs/ho=
stfs_kern.c:242
#6  0x0811a8df in evict (inode=3D0x462ad3b8) at fs/inode.c:549


--=20
MfG/Sincerely
Toralf F=C3=B6rster
pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3

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