Date:	Tue, 22 Apr 2008 00:26:04 +0200
From:	Jiri Slaby <jirislaby@...il.com>
To:	David Miller <davem@...emloft.net>
CC:	torvalds@...ux-foundation.org, rjw@...k.pl,
	linux-kernel@...r.kernel.org, mingo@...e.hu,
	akpm@...ux-foundation.org, linux-ext4@...r.kernel.org,
	herbert@...dor.apana.org.au, paulmck@...ibm.com,
	Zdenek Kabelac <zdenek.kabelac@...il.com>
Subject: Re: 2.6.25-git2: BUG: unable to handle kernel paging request at ffffffffffffffff

On 04/21/2008 11:58 PM, Jiri Slaby wrote:
> Leaving untouched.
> 
> On 04/21/2008 11:18 PM, Jiri Slaby wrote:
>> On 04/21/2008 10:39 PM, David Miller wrote:
>>> From: Linus Torvalds <torvalds@...ux-foundation.org>
>>> Date: Mon, 21 Apr 2008 09:54:07 -0700 (PDT)
>>>
>>>> What I find interesting is that at least for me, I have the SLAB 
>>>> bucket size for nf_conntrack_expect being 208 bytes. And the 
>>>> *biggest* merge by far after 2.6.25 so far has been networking (and 
>>>> conntrack in particular)
>>>>
>>>> Is that a smoking gun? Not necessarily. But it *is* intriguing. But 
>>>> there are other possible clashes (the 192-byte bucket has several 
>>>> different suspects, and not all of them are in networking).1
>>>
>>> I think you might be onto something here.
>>>
>>> The "mask" member of struct nf_conntrack_expect could be reasonably
>>> all 1's like the value reported in the crash that begins this
>>> thread.
>>>
>>> Do we know the offset within the object at which this all 1's
>>> value is found?
>>>
>>> My rough calculations show that on 32-bit that expect->mask member is
>>> at offset 56 and on 64-bit it should be at offset 72.  Does that
>>> match up to the offset of the filp or whatever bit being corrupted?
>>
>> dentry.d_name.name is 56 on 64-bit (my memcmp crashes)
>> dentry.d_hash.next is 24 (crashed at least 3 times here, rafael's one)
>> dentry.d_op is 136 (crash below)
> 
> file.f_mapping is 176 (the another one from -rc8-mm2)
> 
> the one at:
> http://www.opensubscriber.com/message/linux-kernel@vger.kernel.org/9008289.html 
> 
> 
> Having slub_debug enabled, tomorrow will be results, I guess...

Sorry, one more entry:

00000000000000f0 dentry.d_op (Zdenek, offset ? around 136)
00f0000000000000 dentry.d_hash.next (me, offset 24)
ffff81f02003f16c dentry.d_name.name (me, offset 56)
         memory ORed by 000000f000000000
fffff0002004c1b0 file.f_mapping (me, offset 176)
         memory hole, it was something like
         (ffff81002004c1b0 & ~00000f0000000000) | 0000f00000000000?
ffffffffffffffff dentry.d_hash.next (Rafael, offset ? around 24)
         -1, ~0ULL

What are these nibble plays?

>> It's spreading :/.
>>
>> ---------- Forwarded message ----------
>> From: Zdenek Kabelac <zdenek.kabelac@...il.com>
>> Date: 21.4.2008 11:14
>> Subject: BUG: unable to handle kernel NULL pointer at d_free+0x18/0x80
>> To: Kernel development list <linux-kernel@...r.kernel.org>
>>
>>
>> Hello
>>
>>  This oops appeared in my log - unsure how it is related to my DVB-T
>>  tuner test before.
>>  But I've also seen another weird resume with some similar crash.
>>
>>  Happens with 2.6.25 - commit 48a86f548fb74928f9a466f52527e83fecdb4575
>>  (T61, 2GB)
>>
>>
>>  BUG: unable to handle kernel NULL pointer dereference at 
>> 0000000000000110
>>  IP: [d_free+24/128] d_free+0x18/0x80
>>  PGD 0
>>  Oops: 0000 [1] PREEMPT SMP
>>  CPU 0
>>  Modules linked in: usb_storage dvb_usb_af9015 dvb_usb_dibusb_common
>>  dib3000mc dibx000_common dvb_usb dvb_core tun nls_iso8859_2 nls_cp852
>>  vfat fat i915 drm ipt_MASQUERADE iptable_nat nf_nat nf_conntrack_ipv4
>>  xt_state nf_conntrack ipt_REJECT xt_tcpudp iptable_filter ip_tables
>>  x_tables bridge llc nfsd lockd nfs_acl auth_rpcgss exportfs autofs4
>>  sunrpc binfmt_misc dm_mirror dm_log dm_multipath dm_mod uinput
>>  kvm_intel kvm snd_hda_intel arc4 ecb snd_seq_oss crypto_blkcipher
>>  snd_seq_midi_event snd_seq cryptomgr snd_seq_device snd_pcm_oss
>>  crypto_algapi iwl3945 mac80211 e1000e psmouse snd_mixer_oss rtc_cmos
>>  evdev rtc_core thinkpad_acpi video snd_pcm mmc_block sdhci mmc_core
>>  snd_timer iTCO_wdt iTCO_vendor_support battery backlight nvram rtc_lib
>>  i2c_i801 i2c_core ac snd soundcore snd_page_alloc intel_agp output
>>  serio_raw cfg80211 button uhci_hcd ohci_hcd ehci_hcd usbcore [last
>>  unloaded: dvb_core]
>>  Pid: 210, comm: kswapd0 Not tainted 2.6.25 #56
>>  RIP: 0010:[d_free+24/128]  [d_free+24/128] d_free+0x18/0x80
>>  RSP: 0018:ffff81007ced9cf0  EFLAGS: 00010206
>>  RAX: 00000000000000f0 RBX: ffff8100202723d8 RCX: 0000000000000132
>>  RDX: 0000000000005e5d RSI: ffff81007ced4048 RDI: ffff8100202723d8
>>  RBP: ffff81007ced9d00 R08: 0000000000000002 R09: d37a6f4de9bd37a7
>>  R10: 0000000000000000 R11: 0000000000000000 R12: ffff8100202723d8
>>  R13: ffff81007c9329d8 R14: ffff8100202723e0 R15: 0000000000000029
>>  FS:  0000000000000000(0000) GS:ffffffff81486000(0000) 
>> knlGS:0000000000000000
>>  CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
>>  CR2: 0000000000000110 CR3: 0000000001001000 CR4: 00000000000026e0
>>  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>  DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
>>  Process kswapd0 (pid: 210, threadinfo ffff81007ced8000, task 
>> ffff81007ced4000)
>>  Stack:  ffff8100202723d8 ffff81007b7e73d8 ffff81007ced9d20 
>> ffffffff810cb3eb
>>   ffff8100202723d8 0000000000000000 ffff81007ced9d40 ffffffff810cb4d5
>>   ffff8100202723d8 ffff8100202723d8 ffff81007ced9d80 ffffffff810cb642
>>  Call Trace:
>>   [d_kill+59/96] d_kill+0x3b/0x60
>>   [prune_one_dentry+197/240] prune_one_dentry+0xc5/0xf0
>>   [prune_dcache+322/512] prune_dcache+0x142/0x200
>>   [shrink_dcache_memory+65/80] shrink_dcache_memory+0x41/0x50
>>   [shrink_slab+274/480] shrink_slab+0x112/0x1e0
>>   [kswapd+1232/1552] kswapd+0x4d0/0x610
>>   [isolate_pages_global+0/64] ? isolate_pages_global+0x0/0x40
>>   [autoremove_wake_function+0/64] ? autoremove_wake_function+0x0/0x40
>>   [_spin_unlock_irqrestore+69/144] ? _spin_unlock_irqrestore+0x45/0x90
>>   [kswapd+0/1552] ? kswapd+0x0/0x610
>>   [kthread+73/144] kthread+0x49/0x90
>>   [child_rip+10/18] child_rip+0xa/0x12
>>   [restore_args+0/48] ? restore_args+0x0/0x30
>>   [kthread+0/144] ? kthread+0x0/0x90
>>   [child_rip+0/18] ? child_rip+0x0/0x12
>>
>>
>>  Code: 95 49 81 e8 ab ff 21 00 5b 41 5c c9 c3 66 0f 1f 44 00 00 55 48
>>  89 e5 53 48 89 fb 48 83 ec 08 48 8b 87 b8 00 00 00 48 85 c0 74 0b <48>
>>  8b 40 20 48 85 c0 74 02 ff d0 48 83 7b 50 00 74 1e 48 8d bb
>>  RIP  [d_free+24/128] d_free+0x18/0x80
>>   RSP <ffff81007ced9cf0>
>>  CR2: 0000000000000110
>>  ---[ end trace ca143223eefdc828 ]---
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