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I recently upgraded my home server from Ubuntu 10.04 to 12.04.1. It runs the linux-image-server kernel, x86_64 arch.

There's nothing particularly unusual running, I think -- a deluge daemon, apache2, iptables firewall with IP masquerading, DHCP server, bind DNS server which has zone files updated automatically with the hostnames DHCP clients identify themselves with, sshd, nfs server, a handful of other things. This machine is my router -- it sits between the internet and the local network.

Since the upgrade it has been failing intermittently. It'll be fine for a while after booting and then suddenly we'll lose our network connections on wifi. If I plug in a network cable I can't get an IP address from the DHCP server. If I set myself a static IP address I can continue to access the internet just fine. This makes it look like it's the DHCP server that fails (indeed, I run dhclient -v eth0 and nothing responds to the dhcpdiscover shoutouts), noticed when the clients try to renew their IP leases. But wired with a static IP I can still get to the internet, so iptables is still chugging along just fine.

So I try to log in to the machine over SSH, but it seems to hang. If I make ssh verbose I see that it does establish a connection to the server, then fails a little further down the line -- hard to see where exactly.

I note that if I try to grab a web page from its HTTP server I get the page I request but any extra requests made (for images, stylesheets, javascripts) are not served. I can however get these files if I request them directly, for instance from curl.

Is this suggesting that things are going downhill whenever something attempts to fork?

I dragged a monitor and keyboard to the server (it's usually headless) and had a look -- I see stack traces.

I switch to a fresh virtual terminal and attempt to log in. I get a stack trace (general protection fault) after entering my password. Here it is:

Jan  6 20:19:54 localhost kernel: [ 1475.178245] general protection fault: 0000 [#12] SMP 
Jan  6 20:19:54 localhost kernel: [ 1475.178292] CPU 1 
Jan  6 20:19:54 localhost kernel: [ 1475.178309] Modules linked in: btrfs zlib_deflate libcrc32c ufs qnx4 hfsplus hfs minix ntfs vfat msdos fat jfs xfs reiserfs ext2 nfsd nfs lockd fscache auth_rpcgss nfs_acl sunrpc dm_crypt ppdev ipt_REJECT ipt_LOG ipt_MASQUERADE xt_state iptable_mangle iptable_nat nf_nat nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 iptable_filter ip_tables x_tables joydev sp5100_tco edac_core i2c_piix4 serio_raw k8temp edac_mce_amd snd_hda_codec_hdmi snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_timer snd soundcore parport_pc snd_page_alloc mac_hid shpchp lp parport radeon 8139too ttm drm_kms_helper drm pata_atiixp i2c_algo_bit usbhid hid wmi r8169
Jan  6 20:19:54 localhost kernel: [ 1475.178911] 
Jan  6 20:19:54 localhost kernel: [ 1475.178927] Pid: 1305, comm: login Tainted: G    B D      3.2.0-35-generic #55-Ubuntu Gigabyte Technology Co., Ltd. GA-MA785GM-US2H/GA-MA785GM-US2H
Jan  6 20:19:54 localhost kernel: [ 1475.179028] RIP: 0010:[<ffffffff8116589a>]  [<ffffffff8116589a>] kmem_cache_alloc+0x5a/0x140
Jan  6 20:19:54 localhost kernel: [ 1475.179096] RSP: 0018:ffff88006b251d78  EFLAGS: 00010206
Jan  6 20:19:54 localhost kernel: [ 1475.179135] RAX: 0000000000000000 RBX: 00007f062bb91000 RCX: 000000000005b2ed
Jan  6 20:19:54 localhost kernel: [ 1475.179186] RDX: 000000000005b2ec RSI: 0000000000016da0 RDI: ffff88006d408a00
Jan  6 20:19:54 localhost kernel: [ 1475.179236] RBP: ffff88006b251dc8 R08: ffff88006fa96da0 R09: 0000000000000001
Jan  6 20:19:54 localhost kernel: [ 1475.179287] R10: 00000000000000d1 R11: ffff88006b23a8f0 R12: ffff88006d408a00
Jan  6 20:19:54 localhost kernel: [ 1475.179336] R13: 2665c4979a04b7b8 R14: ffffffff811447c5 R15: 00000000000080d0
Jan  6 20:19:54 localhost kernel: [ 1475.179387] FS:  00007f062bb81700(0000) GS:ffff88006fa80000(0000) knlGS:0000000000000000
Jan  6 20:19:54 localhost kernel: [ 1475.179445] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jan  6 20:19:54 localhost kernel: [ 1475.179486] CR2: 00007f9b4d79da00 CR3: 0000000059a34000 CR4: 00000000000006e0
Jan  6 20:19:54 localhost kernel: [ 1475.179536] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Jan  6 20:19:54 localhost kernel: [ 1475.179586] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Jan  6 20:19:54 localhost kernel: [ 1475.179637] Process login (pid: 1305, threadinfo ffff88006b250000, task ffff880036058000)
Jan  6 20:19:54 localhost kernel: [ 1475.179695] Stack:
Jan  6 20:19:54 localhost kernel: [ 1475.179711]  ffff880036058000 0000000000000041 0000000000000001 ffffffff81188cec
Jan  6 20:19:54 localhost kernel: [ 1475.179777]  0000000000000282 00007f062bb91000 ffff88006822ce00 0000000000000001
Jan  6 20:19:54 localhost kernel: [ 1475.179841]  0000000000001000 0000000000000000 ffff88006b251e88 ffffffff811447c5
Jan  6 20:19:54 localhost kernel: [ 1475.179905] Call Trace:
Jan  6 20:19:54 localhost kernel: [ 1475.179928]  [<ffffffff81188cec>] ? path_openat+0xfc/0x3f0
Jan  6 20:19:54 localhost kernel: [ 1475.179971]  [<ffffffff811447c5>] mmap_region+0x2a5/0x4f0
Jan  6 20:19:54 localhost kernel: [ 1475.180012]  [<ffffffff81144d58>] do_mmap_pgoff+0x348/0x360
Jan  6 20:19:54 localhost kernel: [ 1475.180054]  [<ffffffff81144e36>] sys_mmap_pgoff+0xc6/0x230
Jan  6 20:19:54 localhost kernel: [ 1475.180098]  [<ffffffff81018b12>] sys_mmap+0x22/0x30
Jan  6 20:19:54 localhost kernel: [ 1475.180136]  [<ffffffff816655c2>] system_call_fastpath+0x16/0x1b
Jan  6 20:19:54 localhost kernel: [ 1475.180180] Code: 00 4d 8b 04 24 65 4c 03 04 25 50 da 00 00 49 8b 50 08 4d 8b 28 4d 85 ed 0f 84 d8 00 00 00 49 63 44 24 20 49 8b 34 24 48 8d 4a 01 <49> 8b 5c 05 00 4c 89 e8 65 48 0f c7 0e 0f 94 c0 84 c0 74 c2 4d 
Jan  6 20:19:54 localhost kernel: [ 1475.180503] RIP  [<ffffffff8116589a>] kmem_cache_alloc+0x5a/0x140
Jan  6 20:19:54 localhost kernel: [ 1475.180552]  RSP <ffff88006b251d78>
Jan  6 20:19:54 localhost kernel: [ 1475.180603] ---[ end trace 766ef1ef52f774b9 ]---

If I watch long enough, I see more general protection faults. I've seen them for login, apache2, deluge-web, head, powerbtn.sh so far.

I have to hard reset the machine to get it back to a working state (I even get a general protection fault for powerbtn.sh when I hit the power button), but it's not long before it gets like this again.

I haven't yet figured out how to reproduce this on demand -- it seems to happen randomly.

In case it's useful, I looked through kern.log and found the first such fault. There's a ton of them all in a row starting with zsh, then deluged, apache2, cron, head, console-kit-dae, irqbalance, nmbd... Here's the zsh one and the bad page state error which comes right after:

Jan  6 20:13:35 localhost kernel: [ 1096.184250] general protection fault: 0000 [#1] SMP 
Jan  6 20:13:35 localhost kernel: [ 1096.186339] CPU 1 
Jan  6 20:13:35 localhost kernel: [ 1096.186355] Modules linked in: btrfs zlib_deflate libcrc32c ufs qnx4 hfsplus hfs minix ntfs vfat msdos fat jfs xfs reiserfs ext2 nfsd nfs lockd fscache auth_rpcgss nfs_acl sunrpc dm_crypt ppdev ipt_REJECT ipt_LOG ipt_MASQUERADE xt_state iptable_mangle iptable_nat nf_nat nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 iptable_filter ip_tables x_tables joydev sp5100_tco edac_core i2c_piix4 serio_raw k8temp edac_mce_amd snd_hda_codec_hdmi snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_timer snd soundcore parport_pc snd_page_alloc mac_hid shpchp lp parport radeon 8139too ttm drm_kms_helper drm pata_atiixp i2c_algo_bit usbhid hid wmi r8169
Jan  6 20:13:35 localhost kernel: [ 1096.188008] 
Jan  6 20:13:35 localhost kernel: [ 1096.188008] Pid: 2564, comm: zsh Not tainted 3.2.0-35-generic #55-Ubuntu Gigabyte Technology Co., Ltd. GA-MA785GM-US2H/GA-MA785GM-US2H
Jan  6 20:13:35 localhost kernel: [ 1096.188008] RIP: 0010:[<ffffffff8116589a>]  [<ffffffff8116589a>] kmem_cache_alloc+0x5a/0x140
Jan  6 20:13:35 localhost kernel: [ 1096.188008] RSP: 0018:ffff880059877d78  EFLAGS: 00010206
Jan  6 20:13:35 localhost kernel: [ 1096.188008] RAX: 0000000000000000 RBX: 00007f202c59d000 RCX: 000000000005b2ed
Jan  6 20:13:35 localhost kernel: [ 1096.188008] RDX: 000000000005b2ec RSI: 0000000000016da0 RDI: ffff88006d408a00
Jan  6 20:13:35 localhost kernel: [ 1096.188008] RBP: ffff880059877dc8 R08: ffff88006fa96da0 R09: 0000000000000001
Jan  6 20:13:35 localhost kernel: [ 1096.188008] R10: 0000000000100073 R11: ffff880059dbb2c0 R12: ffff88006d408a00
Jan  6 20:13:35 localhost kernel: [ 1096.188008] R13: 2665c4979a04b7b8 R14: ffffffff811447c5 R15: 00000000000080d0
Jan  6 20:13:35 localhost kernel: [ 1096.188008] FS:  00007f202c5ac700(0000) GS:ffff88006fa80000(0000) knlGS:0000000000000000
Jan  6 20:13:35 localhost kernel: [ 1096.188008] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jan  6 20:13:35 localhost kernel: [ 1096.188008] CR2: 00000000025991f0 CR3: 0000000059dbc000 CR4: 00000000000006e0
Jan  6 20:13:35 localhost kernel: [ 1096.188008] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Jan  6 20:13:35 localhost kernel: [ 1096.188008] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Jan  6 20:13:35 localhost kernel: [ 1096.188008] Process zsh (pid: 2564, threadinfo ffff880059876000, task ffff88006b6b5c00)
Jan  6 20:13:35 localhost kernel: [ 1096.188008] Stack:
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  0000000000000001 0000000000001000 0000000000000001 ffffffff8129e2e0
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  0000000000000001 00007f202c59d000 ffff88006822f480 0000000000000001
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  0000000000001000 0000000000000000 ffff880059877e88 ffffffff811447c5
Jan  6 20:13:35 localhost kernel: [ 1096.188008] Call Trace:
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  [<ffffffff8129e2e0>] ? cap_vm_enough_memory+0x50/0x60
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  [<ffffffff811447c5>] mmap_region+0x2a5/0x4f0
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  [<ffffffff81144d58>] do_mmap_pgoff+0x348/0x360
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  [<ffffffff81144eb1>] sys_mmap_pgoff+0x141/0x230
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  [<ffffffff81018b12>] sys_mmap+0x22/0x30
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  [<ffffffff816655c2>] system_call_fastpath+0x16/0x1b
Jan  6 20:13:35 localhost kernel: [ 1096.188008] Code: 00 4d 8b 04 24 65 4c 03 04 25 50 da 00 00 49 8b 50 08 4d 8b 28 4d 85 ed 0f 84 d8 00 00 00 49 63 44 24 20 49 8b 34 24 48 8d 4a 01 <49> 8b 5c 05 00 4c 89 e8 65 48 0f c7 0e 0f 94 c0 84 c0 74 c2 4d 
Jan  6 20:13:35 localhost kernel: [ 1096.188008] RIP  [<ffffffff8116589a>] kmem_cache_alloc+0x5a/0x140
Jan  6 20:13:35 localhost kernel: [ 1096.188008]  RSP <ffff880059877d78>
Jan  6 20:13:35 localhost kernel: [ 1096.274513] ---[ end trace 766ef1ef52f774ae ]---
Jan  6 20:13:37 localhost kernel: [ 1097.836149] BUG: Bad page state in process swapper/0  pfn:59a33
Jan  6 20:13:37 localhost kernel: [ 1097.838885] page:ffffea0001668cc0 count:0 mapcount:-1 mapping:          (null) index:0xffff880059a33160
Jan  6 20:13:37 localhost kernel: [ 1097.841673] page flags: 0x100000000000000()
Jan  6 20:13:37 localhost kernel: [ 1097.844440] Modules linked in: btrfs zlib_deflate libcrc32c ufs qnx4 hfsplus hfs minix ntfs vfat msdos fat jfs xfs reiserfs ext2 nfsd nfs lockd fscache auth_rpcgss nfs_acl sunrpc dm_crypt ppdev ipt_REJECT ipt_LOG ipt_MASQUERADE xt_state iptable_mangle iptable_nat nf_nat nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 iptable_filter ip_tables x_tables joydev sp5100_tco edac_core i2c_piix4 serio_raw k8temp edac_mce_amd snd_hda_codec_hdmi snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_timer snd soundcore parport_pc snd_page_alloc mac_hid shpchp lp parport radeon 8139too ttm drm_kms_helper drm pata_atiixp i2c_algo_bit usbhid hid wmi r8169
Jan  6 20:13:37 localhost kernel: [ 1097.856881] Pid: 0, comm: swapper/0 Tainted: G      D      3.2.0-35-generic #55-Ubuntu
Jan  6 20:13:37 localhost kernel: [ 1097.860020] Call Trace:
Jan  6 20:13:37 localhost kernel: [ 1097.863063]  <IRQ>  [<ffffffff8111fe8f>] bad_page.part.61+0x9f/0xf0
Jan  6 20:13:37 localhost kernel: [ 1097.866119]  [<ffffffff8111fef8>] bad_page+0x18/0x30
Jan  6 20:13:37 localhost kernel: [ 1097.869158]  [<ffffffff8112098e>] free_pages_prepare+0x10e/0x120
Jan  6 20:13:37 localhost kernel: [ 1097.872178]  [<ffffffff81120af9>] free_hot_cold_page+0x49/0x1a0
Jan  6 20:13:37 localhost kernel: [ 1097.875183]  [<ffffffff81120c7d>] __free_pages+0x2d/0x40
Jan  6 20:13:37 localhost kernel: [ 1097.878163]  [<ffffffff8159a8fb>] tcp_v4_destroy_sock+0x25b/0x2c0
Jan  6 20:13:37 localhost kernel: [ 1097.881105]  [<ffffffff81582695>] inet_csk_destroy_sock+0x55/0x140
Jan  6 20:13:37 localhost kernel: [ 1097.883970]  [<ffffffff815849b0>] tcp_done+0x50/0x90
Jan  6 20:13:37 localhost kernel: [ 1097.886853]  [<ffffffff81591d92>] tcp_rcv_state_process+0x422/0x5f0
Jan  6 20:13:37 localhost kernel: [ 1097.889724]  [<ffffffff8159a597>] tcp_v4_do_rcv+0xc7/0x1d0
Jan  6 20:13:37 localhost kernel: [ 1097.892513]  [<ffffffff8159c1f1>] tcp_v4_rcv+0x581/0x820
Jan  6 20:13:37 localhost kernel: [ 1097.895301]  [<ffffffff81577b60>] ? ip_rcv_finish+0x370/0x370
Jan  6 20:13:37 localhost kernel: [ 1097.898110]  [<ffffffff81577b60>] ? ip_rcv_finish+0x370/0x370
Jan  6 20:13:37 localhost kernel: [ 1097.900915]  [<ffffffff81577c3d>] ip_local_deliver_finish+0xdd/0x280
Jan  6 20:13:37 localhost kernel: [ 1097.903716]  [<ffffffff81577fa8>] ip_local_deliver+0x88/0x90
Jan  6 20:13:37 localhost kernel: [ 1097.906502]  [<ffffffff815778fd>] ip_rcv_finish+0x10d/0x370
Jan  6 20:13:37 localhost kernel: [ 1097.909279]  [<ffffffff815781e5>] ip_rcv+0x235/0x300
Jan  6 20:13:37 localhost kernel: [ 1097.912067]  [<ffffffff81613dc7>] ? packet_rcv_spkt+0x47/0x190
Jan  6 20:13:37 localhost kernel: [ 1097.914831]  [<ffffffff81543446>] __netif_receive_skb+0x4d6/0x550
Jan  6 20:13:37 localhost kernel: [ 1097.917624]  [<ffffffff81544230>] netif_receive_skb+0x80/0x90
Jan  6 20:13:37 localhost kernel: [ 1097.920415]  [<ffffffff81536474>] ? __netdev_alloc_skb+0x24/0x50
Jan  6 20:13:37 localhost kernel: [ 1097.923124]  [<ffffffffa00d6e90>] rtl8139_rx+0x150/0x2b0 [8139too]
Jan  6 20:13:37 localhost kernel: [ 1097.925754]  [<ffffffffa00d704a>] rtl8139_poll+0x5a/0xd0 [8139too]
Jan  6 20:13:37 localhost kernel: [ 1097.928274]  [<ffffffff81544bd4>] net_rx_action+0x134/0x290
Jan  6 20:13:37 localhost kernel: [ 1097.930698]  [<ffffffff8103df8b>] ? native_safe_halt+0xb/0x10
Jan  6 20:13:37 localhost kernel: [ 1097.933115]  [<ffffffff8106f6e8>] __do_softirq+0xa8/0x210
Jan  6 20:13:37 localhost kernel: [ 1097.935495]  [<ffffffff810967f5>] ? do_timer+0x25/0x30
Jan  6 20:13:37 localhost kernel: [ 1097.937836]  [<ffffffff81035dc2>] ? ack_apic_level+0x72/0x190
Jan  6 20:13:37 localhost kernel: [ 1097.940163]  [<ffffffff8166782c>] call_softirq+0x1c/0x30
Jan  6 20:13:37 localhost kernel: [ 1097.942464]  [<ffffffff81016305>] do_softirq+0x65/0xa0
Jan  6 20:13:37 localhost kernel: [ 1097.944778]  [<ffffffff8106face>] irq_exit+0x8e/0xb0
Jan  6 20:13:37 localhost kernel: [ 1097.947068]  [<ffffffff816680e3>] do_IRQ+0x63/0xe0
Jan  6 20:13:37 localhost kernel: [ 1097.949327]  [<ffffffff8165d46e>] common_interrupt+0x6e/0x6e
Jan  6 20:13:37 localhost kernel: [ 1097.951597]  <EOI>  [<ffffffff8103df8b>] ? native_safe_halt+0xb/0x10
Jan  6 20:13:37 localhost kernel: [ 1097.953891]  [<ffffffff810900a8>] ? hrtimer_start+0x18/0x20
Jan  6 20:13:37 localhost kernel: [ 1097.956171]  [<ffffffff8101c983>] default_idle+0x53/0x1d0
Jan  6 20:13:37 localhost kernel: [ 1097.958426]  [<ffffffff8101cb5d>] amd_e400_idle+0x5d/0x120
Jan  6 20:13:37 localhost kernel: [ 1097.960704]  [<ffffffff81013236>] cpu_idle+0xd6/0x120
Jan  6 20:13:37 localhost kernel: [ 1097.962970]  [<ffffffff816235ee>] rest_init+0x72/0x74
Jan  6 20:13:37 localhost kernel: [ 1097.965195]  [<ffffffff81cfbc03>] start_kernel+0x3b0/0x3bd
Jan  6 20:13:37 localhost kernel: [ 1097.967421]  [<ffffffff81cfb388>] x86_64_start_reservations+0x132/0x136
Jan  6 20:13:37 localhost kernel: [ 1097.969660]  [<ffffffff81cfb140>] ? early_idt_handlers+0x140/0x140
Jan  6 20:13:37 localhost kernel: [ 1097.971888]  [<ffffffff81cfb459>] x86_64_start_kernel+0xcd/0xdc

What's happening here? What can I do?

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1  
Such widespread errors lead me to suspect your hardware. Have you verified that all your hardware is good? –  Scott Severance Jan 8 '13 at 23:49
    
Is there a good resource you can recommend which shows how to perform such verifications? I'm aware of memtest but nothing else. –  tremby Jan 10 '13 at 1:42
    
I think there are a few good questions about that on this site. But I'm not too good with hardware. If I were you, the first thing I'd do would be to run the system from a live environment (CD or flash drive) and see if you still have the problem. –  Scott Severance Jan 10 '13 at 23:33
1  
First, I'd check the internals of the server. Does the mainboard look OK, loose cables, any very hot components etc. The next good idea is to run memtest. But as your traces appear very early I doubt that it is a memory thing. What hardware has your server? Did you do any tweaking/overclocking? –  qbi Jan 14 '13 at 10:24
2  
In addition to hardware checks, I'd also look at the kernel modules being loaded and/or the kernel itself. You mentioned this happened upon upgrade; are there any version mismatches between the kernel and modules when it happened? Similarly interesting is that the fault message for the 'login' process reports 'Tainted' (usually meaning a non-free driver/module is present), while the 'zsh' fault reports 'Not tainted'. –  YellowApple Jan 22 '13 at 20:20

2 Answers 2

I would use the older kernel (2.6.x) first before jumping onto the hardware. If Ubuntu 10 kernel is still installed, reboot the machine and run the server with the old kernel. Ubuntu 12 is 3.x? while Ubuntu 10 is 2.6.x.

If 2.6 linux-image is not available, you can add the lucid repository to /etc/apt/sources.list.d, do "apt-get update", and "aptitude versions linux-image" and install 2.6 kernel.

If the situation does not change with the older kernel, you can conclude that it's not the kernel but hardware. If the situation improves, it's probably either buggy driver or kernel. AFAIK, using older kernel does not affect your system. I've installed 2.6 kernel from Lucid and used it with Precise in order to avoid the Intel graphics problem and my machine worked just fine.

Only annoying part of it was that I had to hack the "grub" (/etc/grub.d/) in order for the 2.6 kernel to show up in the grub menu so that I can edit /etc/default/grub to choose the 2.6 kernel as default, and I had to edit the /etc/grub.d/ multiple times since every time I take the linux-image update, it reverts the hacked files in /etc/grub.d/*. (Maybe someone else knows how to use the older version of kernel as default in grub.)

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up vote 0 down vote accepted

It seems it was indeed a memory issue. Memtest gave some errors on one of the four modules, and after removing this module it hasn't crashed since. Thanks for all the suggestions.

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