Date:	Thu, 17 Sep 2009 12:58:23 +0300
From:	Denys Fedoryschenko <denys@...p.net.lb>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	gregkh@...e.de, linux-kernel@...r.kernel.org
Subject: Re: unable to handle kernel NULL pointer / tty / 2.6.31-vanilla/ still persists

Sorry it was 2.6.31 vanilla, i change in subject, but forgot to change in 
body.

I had similar crash(old one) in rc7, but it was triggered (seems) by ssh 
bruteforcing. The new one didnt had any ssh messages nearby, but it can be 
disconnection of persistent ssh session, that didn't appear in logs.



On Thursday 17 September 2009 12:35:30 Frederic Weisbecker wrote:
> On Tue, Sep 15, 2009 at 10:32:53AM +0300, Denys Fedoryschenko wrote:
> > Kernel 2.6.31-rc7
> > x86 , 32-bit
> > gcc 4.4.1
>
> Hi,
>
> If you are on -rc7, then you are missing an important fix:
>
> tty: make sure to flush any pending work when halting the ldisc
>
> Have you tried with 2.6.31 ?
>
> Thanks,
> Frederic.
>
> > Happened on heavy network load, looks like as previous one, seems problem
> > still persists.
> > It is hyperthreading Xeon, as i heard on such CPU's SMP bugs most easy to
> > trigger. But for me triggered after few days of operation.
> >
> > Here is oops:
> >
> > [273169.803628] BUG: unable to handle kernel NULL pointer dereference at
> > (null)
> > [273169.803710] IP: [<c0250f08>] process_echoes+0x65/0x240
> > [273169.803785] *pdpt = 000000002f97d001 *pde = 0000000000000000
> > [273169.803854] Oops: 0000 [#1] SMP
> > [273169.803922] last sysfs
> > file: /sys/module/nf_conntrack_ipv4/parameters/hashsize
> > [273169.804045] Modules linked in: ipt_LOG xt_connlimit xt_NOTRACK
> > iptable_raw ip_gre ipt_REJECT ts_bm xt_string nf_conntrack_netlink
> > nfnetlink iptable_nat nf_nat nf_c
> > onntrack_ipv4 nf_conntrack cls_u32 sch_htb tun nf_defrag_ipv
> > [273169.804068]
> > [273169.804068] Pid: 6261, comm: login Not tainted
> > (2.6.31-build-0046-32bit #4)
> > [273169.804068] EIP: 0060:[<c0250f08>] EFLAGS: 00010202 CPU: 1
> > [273169.804068] EIP is at process_echoes+0x65/0x240
> > [273169.804068] EAX: 00000001 EBX: e6cd0800 ECX: 00001f00 EDX: 00001000
> > [273169.804068] ESI: e6cd0800 EDI: 00000000 EBP: f524ad84 ESP: f524ad5c
> > [273169.804068]  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
> > [273169.804068] Process login (pid: 6261, ti=f524a000 task=f6910ae0
> > task.ti=f524a000)
> > [273169.804068] Stack:
> > [273169.804068]  e6cd0bc8 e6cd0bdc 00001f00 00000001 00001000 f524ad84
> > c0250c12 e6cd080a
> > [273169.804068] <0> e6cd0800 e6cd0958 f524ae94 c02528b5 e6cd0800 c2020220
> > 00000000 e6cd0bf8
> > [273169.804068] <0> 00000000 ef07081c 00000000 00000000 ef070820 ef070921
> > 00000000 00000001
> > [273169.804068] Call Trace:
> > [273169.804068]  [<c0250c12>] ? echo_char_raw+0x45/0x4a
> > [273169.804068]  [<c02528b5>] ? n_tty_receive_buf+0xbaf/0x10a5
> > [273169.804068]  [<c02fbc5a>] ? schedule+0x75d/0x7c7
> > [273169.804068]  [<c01706cc>] ? filemap_fault+0x69/0x2e5
> > [273169.804068]  [<c0253d63>] ? tty_ldisc_try+0x36/0x3c
> > [273169.804068]  [<c02548f8>] ? flush_to_ldisc+0xf1/0x17f
> > [273169.804068]  [<c02549e4>] ? tty_flush_to_ldisc+0xd/0xf
> > [273169.804068]  [<c02518d0>] ? n_tty_read+0x2ac/0x5ad
> > [273169.804068]  [<c01293e5>] ? default_wake_function+0x0/0xd
> > [273169.804068]  [<c0251624>] ? n_tty_read+0x0/0x5ad
> > [273169.804068]  [<c024e1b2>] ? tty_read+0x62/0x99
> > [273169.804068]  [<c024e150>] ? tty_read+0x0/0x99
> > [273169.804068]  [<c0190de2>] ? vfs_read+0x87/0x110
> > [273169.804068]  [<c0190f04>] ? sys_read+0x3b/0x60
> > [273169.804068]  [<c0102975>] ? syscall_call+0x7/0xb
> > [273169.804068] Code: 20 00 00 89 45 e0 8b 83 88 03 00 00 8d 90 00 10 00
> > 00 89 c7 8b 83 90 03 00 00 89 55 e8 03 bb 8c 03 00 00 89 45 e4 e9 63 01
> > 00 00 <8a> 07 3c ff 0f
> >  85 35 01 00 00 8d 57 01 3b 55 e8 8d 87 01 f0 ff
> > [273169.804068] EIP: [<c0250f08>] process_echoes+0x65/0x240 SS:ESP
> > 0068:f524ad5c
> > [273169.804068] CR2: 0000000000000000
> > [273169.807602] ---[ end trace 25fadd9ce705aa28 ]---
> > [273169.807701] Kernel panic - not syncing: Fatal exception
> > [273169.807803] Pid: 6261, comm: login Tainted: G      D
> > 2.6.31-build-0046-32bit #4
> > [273169.807964] Call Trace:
> > [273169.808072]  [<c02fb28c>] ? printk+0xf/0x13
> > [273169.808176]  [<c02fb1dd>] panic+0x39/0xd9
> > [273169.808278]  [<c01059b7>] oops_end+0x8b/0x9a
> > [273169.808378]  [<c0118f49>] no_context+0x13d/0x147
> > [273169.808478]  [<c0119066>] __bad_area_nosemaphore+0x113/0x11b
> > [273169.808578]  [<c01357b4>] ? lock_timer_base+0x1f/0x3e
> > [273169.808676]  [<c01359c1>] ? mod_timer+0x108/0x113
> > [273169.808775]  [<c01190ae>] bad_area+0x30/0x39
> > [273169.808874]  [<c0119334>] do_page_fault+0x16b/0x26f
> > [273169.808975]  [<c01191c9>] ? do_page_fault+0x0/0x26f
> > [273169.809087]  [<c02fd2de>] error_code+0x66/0x6c
> > [273169.809195]  [<c025007b>] ? tty_release_dev+0x29e/0x3e0
> > [273169.809377]  [<c01191c9>] ? do_page_fault+0x0/0x26f
> > [273169.809486]  [<c0250f08>] ? process_echoes+0x65/0x240
> > [273169.810939]  [<c0250c12>] ? echo_char_raw+0x45/0x4a
> > [273169.811040]  [<c02528b5>] n_tty_receive_buf+0xbaf/0x10a5
> > [273169.811156]  [<c02fbc5a>] ? schedule+0x75d/0x7c7
> > [273169.811267]  [<c01706cc>] ? filemap_fault+0x69/0x2e5
> > [273169.811368]  [<c0253d63>] ? tty_ldisc_try+0x36/0x3c
> > [273169.811468]  [<c02548f8>] flush_to_ldisc+0xf1/0x17f
> > [273169.811571]  [<c02549e4>] tty_flush_to_ldisc+0xd/0xf
> > [273169.811674]  [<c02518d0>] n_tty_read+0x2ac/0x5ad
> > [273169.811779]  [<c01293e5>] ? default_wake_function+0x0/0xd
> > [273169.811884]  [<c0251624>] ? n_tty_read+0x0/0x5ad
> > [273169.811988]  [<c024e1b2>] tty_read+0x62/0x99
> > [273169.812105]  [<c024e150>] ? tty_read+0x0/0x99
> > [273169.812217]  [<c0190de2>] vfs_read+0x87/0x110
> >
> >
> >
> > --
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