Re: Failure in syscall.open probe

[Arkady <arkady dot miasnikov at gmail dot com>]

After the failure the driver can not be removed - remains "stuck" due
to the failure of the syscall.open probe to decrement the usage
counter on return.

On Fri, Aug 25, 2017 at 10:52 PM, David Smith <dsmith@redhat.com> wrote:
> Arkady,
>
> The "good" news is that I've duplicated your problem. I went ahead and
> filed PR22012 (<https://sourceware.org/bugzilla/show_bug.cgi?id=22012>)
> on this issue so I won't forget it.
>
> I'm looking into it.
>
>
> On Fri, Aug 25, 2017 at 12:25 PM, Arkady <arkady.miasnikov@gmail.com> wrote:
>> Reproduce the problem
>>
>> Run the following one liner on CentOS 6.9
>>
>> stap -e "global AF%;probe syscall.open {tid = tid();AF[tid] =
>> filename;}probe syscall.open.return{tid = tid();delete AF[tid];}"
>>
>> Run a bash loop
>> touch test.txt;while [ 1 ];do cat test.txt;done;
>>
>> Monitor the kernel log
>> tail -f /var/log/messages
>>
>> After a couple of minutes you shall see
>>
>> BUG: scheduling while atomic: cat/87764/0x10000001
>> Modules linked in: test_open(U) fuse rfcomm sco bridge bnep l2cap
>> autofs4 bnx2fc cnic uio fcoe libfcoe libfc 8021q scsi_transport_fc
>> garp stp scsi_tgt llc ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4
>> iptable_filter ip_tables ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6
>> xt_state nf_conntrack ip6table_filter ip6_tables ib_ipoib rdma_ucm
>> ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core
>> ib_addr ipv6 uinput microcode vmware_balloon uvcvideo videodev
>> v4l2_compat_ioctl32 btusb bluetooth rfkill snd_seq_midi e1000
>> snd_seq_midi_event snd_ens1371 snd_rawmidi snd_ac97_codec ac97_bus
>> snd_seq snd_seq_device snd_pcm snd_timer snd soundcore snd_page_alloc
>> sg i2c_piix4 shpchp ext4 jbd2 mbcache sd_mod crc_t10dif sr_mod cdrom
>> mptspi mptscsih mptbase scsi_transport_spi pata_acpi ata_generic
>> ata_piix vmwgfx ttm drm_kms_helper drm i2c_core dm_mirror
>> dm_region_hash dm_log dm_mod [last unloaded: speedstep_lib]
>> Pid: 87764, comm: cat Not tainted 2.6.32-696.10.1.el6.x86_64 #1
>> Call Trace:
>> <#DB>  [<ffffffff81068244>] ? __schedule_bug+0x44/0x50
>> [<ffffffff8154ae0c>] ? schedule+0xa4c/0xb70
>> [<ffffffff812a6216>] ? vsnprintf+0x336/0x5e0
>> [<ffffffff810740aa>] ? __cond_resched+0x2a/0x40
>> [<ffffffff8154b200>] ? _cond_resched+0x30/0x40
>> [<ffffffff812a8b9a>] ? strncpy_from_user+0x4a/0x90
>> [<ffffffffa0705ff9>] ? probe_3602+0x5f9/0x1220 [test_open]
>> [<ffffffff81196c31>] ? sys_open+0x1/0x30
>> [<ffffffffa0707fed>] ? enter_kprobe_probe+0x1ed/0x3a0 [test_open]
>> [<ffffffff815512bb>] ? aggr_pre_handler+0x5b/0xb0
>> [<ffffffff81196c30>] ? sys_open+0x0/0x30
>> [<ffffffff81196c31>] ? sys_open+0x1/0x30
>> [<ffffffff81550cd5>] ? kprobe_exceptions_notify+0x3d5/0x430
>> [<ffffffff81550f45>] ? notifier_call_chain+0x55/0x80
>> [<ffffffff81550faa>] ? atomic_notifier_call_chain+0x1a/0x20
>> [<ffffffff810acd0e>] ? notify_die+0x2e/0x30
>> [<ffffffff8154e815>] ? do_int3+0x35/0xb0
>> [<ffffffff8154e083>] ? int3+0x33/0x40
>> [<ffffffff81196c30>] ? sys_open+0x0/0x30
>
>
>
> --
> David Smith
> Principal Software Engineer
> Red Hat