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need help to explain a kernel crash

Hi there,

At home I've installed a Linux home server. It runs Debian 5 on Kernel version 2.6.26. In detail:

Code:

# cat /etc/debian_version

5.0.2



# cat /proc/version

Linux version 2.6.26-1-amd64 (Debian 2.6.26-13lenny2) (dannf@debian.org) (gcc version 4.1.3 20080704 (prerelease) (Debian 4.1.2-25)) #1 SMP Fri Mar 13 17:46:45 UTC 2009

This night the server crashes and I hope you can help me to find out why. I found this error in syslog:

Code:

Oct 11 01:52:21 cse kernel: [2490344.128169] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008

Oct 11 01:52:21 cse kernel: [2490344.128186] IP: [<ffffffff80296547>] free_block+0x74/0x122

Oct 11 01:52:21 cse kernel: [2490344.128196] PGD 7bc49067 PUD 7bc4c067 PMD 0

Oct 11 01:52:21 cse kernel: [2490344.128204] Oops: 0002 [1] SMP

Oct 11 01:52:21 cse kernel: [2490344.128211] CPU 0

Oct 11 01:52:21 cse kernel: [2490344.128216] Modules linked in: cpufreq_powersave cpufreq_stats cpufreq_conservative cpufreq_ondemand cpufreq_userspace ipv6 loop i2c_piix4 pcsp$

Oct 11 01:52:22 cse kernel: [2490344.128301] Pid: 184, comm: kswapd0 Not tainted 2.6.26-1-amd64 #1

Oct 11 01:52:22 cse kernel: [2490344.128307] RIP: 0010:[<ffffffff80296547>]  [<ffffffff80296547>] free_block+0x74/0x122

Oct 11 01:52:22 cse kernel: [2490344.128318] RSP: 0018:ffff81007b6d9cd0  EFLAGS: 00010082

Oct 11 01:52:22 cse kernel: [2490344.128324] RAX: 0000000000000303 RBX: ffff81007b0a7380 RCX: ffff81007ac5d5c0

Oct 11 01:52:22 cse kernel: [2490344.131573] RDX: 0000000000000000 RSI: ffff81003b0d5080 RDI: ffff81001b0d53c0

Oct 11 01:52:22 cse kernel: [2490344.131573] RBP: ffff81001b0d53c0 R08: 0000000000000008 R09: ffff810001101180

Oct 11 01:52:22 cse kernel: [2490344.131573] R10: 0000000000000002 R11: ffffffffa015d275 R12: ffff81007b075858

Oct 11 01:52:22 cse kernel: [2490344.131573] R13: 0000000000000008 R14: 0000000000000000 R15: 000000000000001b

Oct 11 01:52:22 cse kernel: [2490344.131573] FS:  0000000043e82950(0000) GS:ffffffff8053c000(0000) knlGS:00000000f735fb90

Oct 11 01:52:22 cse kernel: [2490344.131573] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b

Oct 11 01:52:22 cse kernel: [2490344.131573] CR2: 0000000000000008 CR3: 000000007b1c3000 CR4: 00000000000006e0

Oct 11 01:52:22 cse kernel: [2490344.131573] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

Oct 11 01:52:22 cse kernel: [2490344.131573] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400

Oct 11 01:52:22 cse kernel: [2490344.131573] Process kswapd0 (pid: 184, threadinfo ffff81007b6d8000, task ffff81007d016200)

Oct 11 01:52:22 cse kernel: [2490344.131573] Stack:  0000000000000020 000000000000001b 0000000000000000 ffff81007ac5d5c0

Oct 11 01:52:22 cse kernel: [2490344.131573]  ffff81007b075800 ffff81007b0a7380 0000000000000180 ffffffff8029675c

Oct 11 01:52:22 cse kernel: [2490344.131573]  ffff81007b075800 ffff81007b0a7380 000000000000002f ffff8100434096b8

Oct 11 01:52:22 cse kernel: [2490344.131573] Call Trace:

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff8029675c>] ? cache_flusharray+0xa4/0xd1

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff80296453>] ? kmem_cache_free+0x174/0x197

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff802ad34f>] ? dispose_list+0xbf/0xee

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff802ad54e>] ? shrink_icache_memory+0x1d0/0x200

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff8027b2d5>] ? shrink_slab+0xe2/0x159

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff8027ba59>] ? kswapd+0x326/0x4a3

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff8027a5e7>] ? isolate_pages_global+0x0/0x2f

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff804289bf>] ? thread_return+0x6b/0xac

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff802461b1>] ? autoremove_wake_function+0x0/0x2e

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff8027b733>] ? kswapd+0x0/0x4a3

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff8024608b>] ? kthread+0x47/0x74

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff80230196>] ? schedule_tail+0x27/0x5c

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff8020cf28>] ? child_rip+0xa/0x12

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff80246044>] ? kthread+0x0/0x74

Oct 11 01:52:22 cse kernel: [2490344.131573]  [<ffffffff8020cf1e>] ? child_rip+0x0/0x12

Oct 11 01:52:22 cse kernel: [2490344.131573]

Oct 11 01:52:22 cse kernel: [2490344.131573]

Oct 11 01:52:22 cse kernel: [2490344.131573] Code: 40 00 00 48 85 c0 74 04 48 8b 52 10 80 3a 00 78 04 0f 0b eb fe 48 8b 72 30 49 63 c6 48 8b 8c c3 68 01 00 00 48 8b 16 48 8b 46$

Oct 11 01:52:22 cse kernel: [2490344.131573] RIP  [<ffffffff80296547>] free_block+0x74/0x122

Oct 11 01:52:22 cse kernel: [2490344.131573]  RSP <ffff81007b6d9cd0>

Oct 11 01:52:22 cse kernel: [2490344.131573] CR2: 0000000000000008

Oct 11 01:52:22 cse kernel: [2490344.131573] ---[ end trace 358acc5ec16358be ]---

If you need additional information please let me know. I don't know what informations are useful because I don't know where to start searching for the error :/

Thank you very much.

bye
Phil

Quote:

Originally Posted by phil333 (Post 3715145)

Hi there,

At home I've installed a Linux home server. It runs Debian 5 on Kernel version 2.6.26. In detail:

Code:

# cat /etc/debian_version

5.0.2



# cat /proc/version

Linux version 2.6.26-1-amd64 (Debian 2.6.26-13lenny2) (dannf@debian.org) (gcc version 4.1.3 20080704 (prerelease) (Debian 4.1.2-25)) #1 SMP Fri Mar 13 17:46:45 UTC 2009

This night the server crashes and I hope you can help me to find out why. I found this error in syslog:

Code:

Oct 11 01:52:21 cse kernel: [2490344.128169] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008

If you need additional information please let me know. I don't know what informations are useful because I don't know where to start searching for the error :/

Thank you very much.

bye
Phil

Sorry? What is your request? Kernel crashes are relatively rare, and most distributions now have an automatic kernel crash reporting system so the problem can be addressed in the most efficient way.

But this isn't a practical or useful way to deal with a kernel crash.

Quote:

Originally Posted by lutusp (Post 3715151)

Sorry, I didn't know that kernel crashes are reported automatically. I just don't know what to do at the moment. And because I'm interested in the reason of the crash I hope somebody can give me some tips what I can do or where I can search to find the problem...

Quote:

Originally Posted by lutusp (Post 3715151)

this isn't a practical or useful way to deal with a kernel crash.

So, what would be a "practical or useful way" to deal with a kernel crash then? Any pointers for the OP other than "automatic kernel crash reporting"?

Quote:

Originally Posted by unSpawn (Post 3715244)

So, what would be a "practical or useful way" to deal with a kernel crash then? Any pointers for the OP other than "automatic kernel crash reporting"?

No, not for a relative newcomer to the Linux world. The reason is that kernel crashes tend to be very complex to unravel, and without an automatic reporting system enabled, there is little point in trying to sort them out or try to report them.

Since it's kswapd barfing on freeing a block (meaning not some userland taint), shouldn't the OP be pointed to running 'ksymoops' and redirected to the Debian bug tracker to add ksymoops info to a ticket?

Quote:

Originally Posted by unSpawn (Post 3716884)

You just proved my point.

Quote:

Originally Posted by lutusp (Post 3717052)

(..) without an automatic reporting system (..) there is little point in trying to sort them out or try to report them

which is not helpful as it doesn't help the OP resolve his issues.

Quote:

Originally Posted by lutusp (Post 3717052)

You just proved my point.

If you know what to do: offer guidance and advice. If you know where people look elsewhere: send 'em there. Else just don't. And you definately shouldn't try to play that kind of games with me.

Hello phil333,

in the log there is something about

Code:

Modules linked in: cpufreq_powersave cpufreq_stats cpufreq_conservative cpufreq_ondemand cpufreq_userspace ipv6 loop i2c_piix4 pcsp$

Powersaving for a server may cause unexpected results.

Markus

Quote:

Originally Posted by unSpawn (Post 3717874)

I tried to nudge you on the friendly way, but you seem impervious to that... OK. Well, your previous replies basically boiled down to telling people to either ignore the error or not bothering reporting them, as evidenced by you saying:
which is not helpful as it doesn't help the OP resolve his issues.

If you know what to do: offer guidance and advice. If you know where people look elsewhere: send 'em there. Else just don't. And you definately shouldn't try to play that kind of games with me.

What game would that be? I advised the OP that without an automatic reporting system, his present quest will only lead to arcana and pointless frustration, and you then advised him in this way:

Quote:

Originally Posted by unSpawn (Post 3717874)

Which any intelligent person will recognize as confirmation of the point I was making. Which leads me to suggest that you not try playing that game with me.