Re: bad pmd filemap.c, oops; 2.4.30 and 2.4.32

From: Chris Stromsoe <cbs@cts.ucla.edu>
To: Willy Tarreau <willy@w.ods.org>
Cc: Marcelo Tosatti <marcelo.tosatti@cyclades.com>,
	linux-kernel@vger.kernel.org
Subject: Re: bad pmd filemap.c, oops; 2.4.30 and 2.4.32
Date: Thu, 29 Dec 2005 01:33:47 -0800 (PST)	[thread overview]
Message-ID: <Pine.LNX.4.64.0512282322280.13624@potato.cts.ucla.edu> (raw)
In-Reply-To: <20051229051238.GU15993@alpha.home.local>

On Thu, 29 Dec 2005, Willy Tarreau wrote:
> On Wed, Dec 28, 2005 at 06:52:06PM -0800, Chris Stromsoe wrote:
>>
>> Dec 27 09:28:19 filemap.c:2234: bad pmd 020001e3.
>> Dec 27 09:28:19 filemap.c:2234: bad pmd 024001e3.
>>
>> The oops came in ata 09:28:20
>>
>> ksymoops 2.4.9 on i686 2.4.32.  Options used
>>      -V (default)
>>      -k /proc/ksyms (default)
>>      -l /proc/modules (default)
>>      -o /lib/modules/2.4.32/ (default)
>>      -m /boot/System.map-2.4.32 (specified)
>>
>> Unable to handle kernel paging request at virtual address c22eee80
>> c0259bb3
>> *pde = 020001e3
>> Oops: 0002
>> CPU:    2
>       ^^^^^
> interesting, this machine is SMP.
> memtest86 only involves CPU0 in tests. I've already had a great difficulty
> trying to detect memory problems which occured only when more than one CPU
> was accessing the RAM. Can your machine support its load with only one CPU ?
> Maybe you observe more I/O than pure CPU. It would be interesting to restart
> it with the 'nosmp' boot option.

The machine is a dual P4 Xeon with hyperthreading on.  It can probably get 
by with only one cpu enabled.  If/when it goes down again, I'll boot with 
nosmp.  For what it's worth, I ran a Dell memory tester ("MP Memory") 
which claims to test all of the CPUs for a few hours and didn't come up 
with anything.  The machine feeds usenet and is seeing a lot more io than 
cpu.  (There are two Adaptec controllers, 4 channels, aic79xx, 5 drives on 
one channel, 3 unused, spool is on a 4 disk raid5, jfs formatted.)

>> EIP:  0010:[alloc_skb+275/480] Not tainted
>
> I'm somewhat surprized, because I've not found a direct nor indirect 
> call path from alloc_skb() to filemap_sync_pte_range() in which the 
> error is reported. I'm clearly missing something here.

If it helps, the oops with 2.4.30 had two "bad pmd" messages right before 
it then:

Unable to handle kernel paging request at virtual address c13aef08
  printing eip:
c012d7b6
*pde = 010001e3
*pte = ce919a00
Oops: 0000
CPU:    1
EIP:    0010:[mark_page_accessed+6/48]    Not tainted
EFLAGS: 00010296
eax: c13aeef0   ebx: c13aeef0   ecx: 0005d800   edx: ee030900
esi: 0005d7a0   edi: 0005d8a9   ebp: f66b1c3c   esp: f66b1c38
ds: 0018   es: 0018   ss: 0018
Process innfeed (pid: 526, stackpage=f66b1000)
Stack: c13aeef0 f66b1c70 c012ea08 ee030900 0005d7a0 0005d8a9 0005d8a9 f7fa1d60
        f6628080 f6628144 f7628200 ee030900 c012e830 f77f4d80 f66b1cb8 c012a18e
        ee030900 63ca0000 00000000 f66b1ce4 c027404c 00000000 f77f4d80 00000106
Call Trace:    [filemap_nopage+472/544] [filemap_nopage+0/544][do_no_page+126/608] [ip_queue_xmit+780/1424] [handle_mm_fault+121/272]
   [do_page_fault+1024/1472] [tcp_write_xmit+353/688] [tcp_new_space+137/160][tcp_rcv_established+716/2480] [memcpy_toiovec+67/112] [do_page_fault+0/1472]
   [error_code+52/60] [csum_partial_copy_generic+61/260] [tcp_sendmsg+2367/4512] [inet_sendmsg+65/80] [sock_sendmsg+102/176] [sock_readv_writev+116/176]
   [sock_writev+79/96] [do_readv_writev+567/608] [sys_writev+88/128] [system_call+51/56]

Code: 8b 40 18 a8 80 75 07 8b 43 18 a8 04 75 0c f0 0f ba 6b 18 02

-Chris