Re: BUG: soft lockup for a user mode linux image

[Richard Weinberger <richard@nod.at>]

Am 03.10.2013 20:54, schrieb Toralf Förster:
> On 10/02/2013 09:55 PM, Richard Weinberger wrote:
>> On Wed, Oct 2, 2013 at 8:30 PM, Toralf Förster <toralf.foerster@gmx.de> wrote:
>>> Running trinity (1 process, no victim files, just "$>trinity -C1) for a longer time
>>> within a 32 bit user mode linux image with a recent git kernel (host: 3.11.3 guest 3.12-rc3-g...)
>>> yields into this konsole message :
>>>
>>>  * Starting local
>>> net.core.warnings = 0                                                                         [ ok ]
>>> BUG: soft lockup - CPU#0 stuck for 23s! [trinity-child0:2031]
>>>
>>>
>>> and at the host t1 of the "linux"-processes eats all CPU cycles at 1 CPU core.
>>> 2 subsequent made back traces made with
>>>
>>> $> sudo gdb /home/tfoerste/devel/linux/linux 28144 -n -batch -ex bt
>>>
>>> shows nearly a similar position around __get_user_pages() - both are attached.
>>>
>>> I'm not surprised that trinity harms a systems - I'm just wondering whether this particular picture is
>>> expected or if it points to an issue.
>>>
>>>
>>> FWIW the last lines of trinity log were :
>>>
>>>
>>> [2031] [94] setsid() = 2031
>>> [2031] [95] setresgid(rgid=0xffff33e3, egid=0xffffff93, sgid=0x22000040) = -1 (Operation not permitted)
>>> [2031] [96] vmsplice(fd=5, iov=0x85501e0, nr_segs=300, flags=9) = 0x3000
>>> [2031] [97] setresuid(ruid=0x80549193, euid=0xc61041e0, suid=0xff19b6fa) = -1 (Operation not permitted)
>>> [2031] [98] setpriority(which=0xff010000, who=0xf3737373, niceval=0x8088960c) = -1 (Invalid argument)
>>> [2031] [99] socketcall(call=1, args=0x8550200) = -1 (Address family not supported by protocol)
>>> [2031] [100] access(filename="�", mode=2017) = -1 (Invalid argument)
>>> [2031] [101] getgroups(gidsetsize=0, grouplist=0x80d0000[page_rand]) = 3
>>> [2031] [102] msync(start=0xc0100220, len=0, flags=3) = -1 (Invalid argument)
>>> [2031] [103] sigpending(set=0x40025000) = 0
>>> [2031] [104] signalfd4(ufd=383, user_mask=1, sizemask=0xa4200000, flags=0x80800) = -1 (Invalid argument)
>>> [2031] [105] sendfile(out_fd=383, in_fd=382, offset=0, count=4096) = -1 (Invalid argument)
>>> [2031] [106] fanotify_mark(fanotify_fd=382, flags=5, mask=0x8000023, dfd=382, pathname="/proc/1092/task/1092/fdinfo/68") = -1 (Invalid argument)
>>> [2031] [107] wait4(upid=1, stat_addr=4, options=0xd761979b, ru=8) = -1 (Invalid argument)
>>> [2031] [108] sigpending(set=0x80ca000[page_zeros]) = 0
>>> [2031] [109] setresuid(ruid=0xefffd6fc, euid=0x1bf4c92f, suid=0xffff2e33) = -1 (Operation not permitted)
>>> [2031] [110] munlock(addr=0x40025000, len=34) = 0
>>> [2031] [111] timer_delete(timer_id=0xffffffdc) = -1 (Invalid argument)
>>> [2031] [112] sched_get_priority_max(policy=0x10000040) = -1 (Invalid argument)
>>> [2031] [113] syslog(type=0xc1000000, buf=1, len=0x82a5) = -1 (Operation not permitted)
>>> [2031] [114] setpriority(which=0xc4c806c6, who=0xffffff01, niceval=0xffff0682) = -1 (Invalid argument)
>>> [2031] [115] getgroups16(gidsetsize=0xfffe, grouplist=1) = -1 (Bad address)
>>> [2031] [116] rename(oldname=4, newname=8) = -1 (Bad address)
>>> [2031] [117] inotify_init() = 654
>>> [2031] [118] getgid() = 100
>>> [2031] [119] fstatat64(dfd=382, filename="/sys/devices/virtual/net/sit0/duplex", statbuf=0, flag=0xb545d727) = -1 (Invalid argument)
>>> [2031] [120] unlinkat(dfd=382, pathname="/proc/sys/net/ipv4/neigh/default/retrans_time", flag=0xc00ef76) = -1 (Invalid argument)
>>> [2031] [121] timerfd_create(clockid=0, flags=0) = 655
>>> [2031] [122] munlock(addr=4, len=0x3fff) = -1 (Cannot allocate memory)
>>> [2031] [123] fremovexattr(fd=382, name=0) = -1 (Bad address)
>>> [2031] [124] sched_get_priority_min(policy=0xff58bfef) = -1 (Invalid argument)
>>> [2031] [125] mq_timedreceive(mqdes=397, u_msg_ptr=4, msg_len=5245, u_msg_prio=0xc0100220, u_abs_timeout=0xc0100220) = -1 (Bad address)
>>> [2031] [126] chdir(filename="/proc/116/net/ptype") = -1 (Not a directory)
>>> [2031] [127] ssetmask(newmask=0x88000092) = 0
>>> [2031] [128] statfs(pathname="/proc/6/mounts", buf=0) = -1 (Bad address)
>>> [2031] [129] fchown16(fd=397, user=104, group=0x94100000) = -1 (Operation not permitted)
>>> [2031] [130] fchdir(fd=397) = -1 (Not a directory)
>>> [2031] [131] mkdir(pathname="/proc/1092/task/1092/fdinfo/316", mode=525) = -1 (File exists)
>>> [2031] [132] fsetxattr(fd=386, name=0x856f158, value=0x8571160, size=0, flags=0) = -1 (Numerical result out of range)
>>> [2031] [133] io_setup(nr_events=4095, ctxp=0x40266000) ^CKilled by signal 2.
>>
>> Reading your gdb backtraces show that schedule_timeout() got called
>> with a negative value.
>> Looks like an integer overflow.
>> The soft-lockup might also origin from that (very big integer which
>> did not overflow jet)
>>
> 
> If the culprit is solved by this patch I'd like to send it out. But I'm
> unsure whether it catches the culprit or if it just covers the root cause.

I fear your Patch will not fix the issue.

Does the issue only trigger on 32bit UMLs?
How long does it take till trinity hits it?

Thanks,
//richard

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