On Sat, Aug 06, 2011 at 03:01:27PM +0200, Urban Loesch wrote: > Am 06.08.2011 14:38, schrieb Herbert Poetzl: >> On Sat, Aug 06, 2011 at 02:13:37PM +0200, Urban Loesch wrote: >>> Hi Herbert, >>>> I just tried to pinpoint the location based on my >>>> 2.6.38.8-vs2.3.0.37-rc17 kernel and I suspect that >>>> task_rq(p) is causing this (for certain p), but >>>> I was wondering why your task_rq_lock() is 0xa0 >>>> bytes in size, where mine is just 0x65 bytes ... >>>> especially as the task_rq_lock function is quite >>>> compact ... >>>> could you upload the output of the folling commands >>>> for me (executed in the build directory of your >>>> kernel or with the vmlinux object file) >>>> # objdump -t vmlinux | grep task_rq_lock >>> gives me only on line: >> that's fine, nothing more was expected :) >>> /usr/src/linux-2.6.38.8 # objdump -t vmlinux | grep task_rq_lock >>> ffffffff8104ec60 l F .text 000000000000009c task_rq_lock >>>> # objdump -d vmlinux --start-address=0x`objdump -t vmlinux | sed -n >>>> '/task_rq_lock/ {s/ .*//; p}'` | sed '/task>:/ Q' >>> more lines :-) >>> You can download it at http://www.enas.net/objdump.txt >> I copied the interesting part here: >> ffffffff8104ec60<task_rq_lock>: >> ffffffff8104ec60: 55 push %rbp >> ffffffff8104ec61: 48 89 e5 mov %rsp,%rbp >> ffffffff8104ec64: 48 83 ec 20 sub $0x20,%rsp >> ffffffff8104ec68: 48 89 1c 24 mov %rbx,(%rsp) >> ffffffff8104ec6c: 4c 89 64 24 08 mov %r12,0x8(%rsp) >> ffffffff8104ec71: 4c 89 6c 24 10 mov %r13,0x10(%rsp) >> ffffffff8104ec76: 4c 89 74 24 18 mov %r14,0x18(%rsp) >> ffffffff8104ec7b: e8 40 d0 fb ff callq >> ffffffff8100bcc0<mcount> >> this suggests that you have FTRACE enabled in your >> kernel and probably a bunch of related TRACERS >> ffffffff8104ec80: 48 c7 c3 40 3c 01 00 mov $0x13c40,%rbx >> ffffffff8104ec87: 49 89 fc mov %rdi,%r12 >> ffffffff8104ec8a: 49 89 f5 mov %rsi,%r13 >> ffffffff8104ec8d: ff 14 25 00 34 a1 81 callq *0xffffffff81a13400 >> ffffffff8104ec94: 48 89 c2 mov %rax,%rdx >> ffffffff8104ec97: ff 14 25 10 34 a1 81 callq *0xffffffff81a13410 >> ffffffff8104ec9e: 49 89 55 00 mov %rdx,0x0(%r13) >> ffffffff8104eca2: 49 8b 44 24 08 mov 0x8(%r12),%rax >> ffffffff8104eca7: 49 89 de mov %rbx,%r14 >> ffffffff8104ecaa: 8b 40 18 mov 0x18(%rax),%eax >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> this is where your problem happens, and together with >> the information from the original post (which you >> removed) this looks like task_rq looking for a task at >> 0x9066669066666605 which is rather unlikely to be a >> valid address, so to me this looks like some kind of >> memory corruption, maybe caused by a completely >> different subsystem ... >> ffffffff8104ecad: 4c 03 34 c5 00 d4 ab add >> -0x7e542c00(,%rax,8),%r14 >> ffffffff8104ecb4: 81 >> ffffffff8104ecb5: 4c 89 f7 mov %r14,%rdi >> ffffffff8104ecb8: e8 43 14 54 00 callq >> ffffffff81590100<_raw_spin_lock> >> ffffffff8104ecbd: 49 8b 44 24 08 mov 0x8(%r12),%rax >> ffffffff8104ecc2: 8b 40 18 mov 0x18(%rax),%eax >> ffffffff8104ecc5: 48 8b 14 c5 00 d4 ab mov >> -0x7e542c00(,%rax,8),%rdx >> ffffffff8104eccc: 81 >> ffffffff8104eccd: 48 8d 04 13 lea (%rbx,%rdx,1),%rax >> ffffffff8104ecd1: 49 39 c6 cmp %rax,%r14 >> ffffffff8104ecd4: 75 18 jne >> ffffffff8104ecee<task_rq_lock+0x8e> >> ffffffff8104ecd6: 4c 89 f0 mov %r14,%rax >> ffffffff8104ecd9: 48 8b 1c 24 mov (%rsp),%rbx >> ffffffff8104ecdd: 4c 8b 64 24 08 mov 0x8(%rsp),%r12 >> ffffffff8104ece2: 4c 8b 6c 24 10 mov 0x10(%rsp),%r13 >> ffffffff8104ece7: 4c 8b 74 24 18 mov 0x18(%rsp),%r14 >> ffffffff8104ecec: c9 leaveq >> ffffffff8104eced: c3 retq >> ffffffff8104ecee: 49 8b 75 00 mov 0x0(%r13),%rsi >> ffffffff8104ecf2: 4c 89 f7 mov %r14,%rdi >> ffffffff8104ecf5: e8 86 14 54 00 callq >> ffffffff81590180<_raw_spin_unlock_irqrestore> >> ffffffff8104ecfa: eb 91 jmp >> ffffffff8104ec8d<task_rq_lock+0x2d> >> ffffffff8104ecfc: 0f 1f 40 00 nopl 0x0(%rax) >> but that's just a wild guess and some hand waving, to >> get better information and more debug info we would >> first need to find a way to trigger this issue within >> a short amount of time, let's say a few minutes up to >> an hour or so ... > I have no idea how can I do this. setup a test system, where you can hit one of your guests (or several of them at once) with artificial stress tests (like a page impression performance test or so) and monitor the kernel output (best via serial console) compile the kernel with DEBUG_INFO enabled so that we can more precise pinpointing in case of a kernel trace >> btw, does it happen on more than one system or is it >> always the same system? > This happend on two of my servers with heavy apache load. > DELL PE R610 and PE R410. Both with 32GB of ram. > The first time was in June on my R410 with kernel 2.6.38.6-vs2.3.0.37-rc15 > It gets me the following error in syslog: > BUG: unable to handle kernel paging request at 00000000801f0f1d > [2472685.774427] IP: [<ffffffff8103695a>] task_rq_lock+0x4a/0xa0 > [2472685.774505] PGD 3164b1067 PUD 0 > [2472685.774574] Oops: 0000 [#1] SMP > [2472685.774647] last sysfs file: /sys/module/drbd/parameters/cn_idx > [2472685.774716] CPU 9 > [2472685.774723] Modules linked in: dca netconsole configfs drbd > lru_cache sch_hfsc ip6_queue act_police cls_flow cls_fw cls_u32 sch_htb > sch_ingress sch_sfq xt_realm iptable_raw ip6t_LOG xt_connlimit ipt_ULOG > ipt_REJECT ip6table_raw ipt_REDIRECT ipt_NETMAP ipt_MASQUERADE ipt_ECN > ipt_ecn ipt_CLUSTERIP ipt_ah ipt_addrtype nf_nat_tftp nf_nat_snmp_basic > nf_nat_sip xt_comment nf_nat_pptp ip6t_REJECT nf_nat_proto_gre > nf_nat_irc nf_nat_h323 nf_nat_ftp nf_nat_amanda xt_recent > ip6table_mangle nf_conntrack_ipv6 nf_conntrack_tftp nf_conntrack_sip > nf_conntrack_sane nf_conntrack_proto_udplite nf_conntrack_proto_sctp > nf_conntrack_pptp nf_conntrack_proto_gre nf_conntrack_netlink > nf_conntrack_netbios_ns nf_conntrack_irc nf_conntrack_h323 > nf_conntrack_ftp ts_kmp nf_conntrack_amanda xt_TPROXY nf_tproxy_core > nf_defrag_ipv6 xt_time xt_TCPMSS xt_tcpmss xt_sctp xt_NFLOG > nfnetlink_log xt_policy xt_pkttype xt_physdev xt_owner xt_NFQUEUE > xt_multiport ipt_LOG xt_mark xt_mac xt_limit iptable_nat xt_length > xt_iprange nf_nat xt_helper nf_conntrack_ipv4 xt_hashlimit > nf_defrag_ipv4 xt_DSCP xt_dscp iptable_mangle xt_dccp xt_connmark > xt_CLASSIFY xt_tcpudp xt_state xt_conntrack nf_conntrack nfnetlink > iptable_filter ip_tables ip6table_filter ip6_tables x_tables > ipmi_devintf ipmi_si ipmi_msghandler mptctl psmouse processor joydev > serio_raw tpm_tis tpm i7core_edac pcspkr tpm_bios edac_core dcdbas > power_meter button mptsas mptscsih mptbase usbhid bnx2 > scsi_transport_sas hid e1000e [last unloaded: igb] > [2472685.776398] > [2472685.776459] Pid: 19778, comm: apache2 Not tainted > 2.6.38.6-vs2.3.0.37-rc15-rol-em64t #7 Dell Inc. PowerEdge R410/0N051F > [2472685.776608] RIP: 0010:[<ffffffff8103695a>] [<ffffffff8103695a>] > task_rq_lock+0x4a/0xa0 > [2472685.776743] RSP: 0018:ffff880121b75dc8 EFLAGS: 00010082 > [2472685.776811] RAX: 00000000801f0f05 RBX: 0000000000011d00 RCX: > 0000000000000040 > [2472685.776936] RDX: 0000000000000282 RSI: ffff880121b75e20 RDI: > 00007f4cfa5fd9a0 > [2472685.777057] RBP: ffff880121b75de8 R08: dead000000200200 R09: > dead000000100100 > [2472685.777178] R10: dead000000200200 R11: dead000000100100 R12: > 00007f4cfa5fd9a0 > [2472685.777299] R13: ffff880121b75e20 R14: 0000000000011d00 R15: > 0000000000000000 > [2472685.777420] FS: 00007f4cfb0a2730(0000) GS:ffff8800bf480000(0000) > knlGS:0000000000000000 > [2472685.777542] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [2472685.777608] CR2: 00000000801f0f1d CR3: 00000002884d7000 CR4: > 00000000000006e0 > [2472685.777728] DR0: 0000000000000000 DR1: 0000000000000000 DR2: > 0000000000000000 > [2472685.777848] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: > 0000000000000400 > [2472685.777968] Process apache2 (pid: 19778, threadinfo > ffff880121b74000, task ffff8801167114d0) > [2472685.778091] Stack: > [2472685.778150] 00007f4cfa5fd9a0 ffff88044db61eb8 000000000000000f > 0000000000000000 > [2472685.778280] ffff880121b75e58 ffffffff81040bd6 ffff880121b75e48 > ffffffff81269f47 > [2472685.778410] 0000000000000000 ffff88081eaafe30 ffff880121b75e28 > 0000000000000282 > [2472685.778540] Call Trace: > [2472685.778604] [<ffffffff81040bd6>] try_to_wake_up+0x36/0x310 > [2472685.778671] [<ffffffff81269f47>] ? idr_remove+0x187/0x1f0 > [2472685.778739] [<ffffffff81040f05>] wake_up_process+0x15/0x20 > [2472685.778806] [<ffffffff81231580>] freeary+0x1e0/0x260 > [2472685.778872] [<ffffffff81232631>] T.616+0x71/0xf0 > [2472685.778939] [<ffffffff8113376b>] ? fput+0x1cb/0x280 > [2472685.779005] [<ffffffff81232719>] sys_semctl+0x69/0xa0 > [2472685.779074] [<ffffffff81002882>] system_call_fastpath+0x16/0x1b > [2472685.779142] Code: 00 48 c7 c3 00 1d 01 00 49 89 fc 49 89 f5 9c 58 > 0f 1f 44 00 00 48 89 c2 fa 66 0f 1f 44 00 00 49 89 55 00 49 8b 44 24 08 > 49 89 de <8b> 40 18 4c 03 34 c5 e0 b2 70 81 4c 89 f7 e8 73 93 4a 00 49 8b > [2472685.779515] RIP [<ffffffff8103695a>] task_rq_lock+0x4a/0xa0 > [2472685.779584] RSP <ffff880121b75dc8> > [2472685.779647] CR2: 00000000801f0f1d > [2472685.780031] ---[ end trace 63c260cc5b2dc0a5 ]--- > On this server are running 4 vServers (all with debian lenny and apache > installed). > On my PER610 is running only one vServer with debian etch (apache, > php5-fcgi, mysql 5.0). interestingly both kernel traces include sys_semctl, so it might be related to the code handling the semaphores maybe just try to bang on that a little (from inside the guest) to see if something triggers ... best, Herbert > thanks, > Urban >> best, >> Herbert >>> thanks, >>> Urban