[Bug uprobes/6842] New: system-wide utrace syscall tracing will cause kernel panic by hackbench.

["mhiramat at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

I ran below script on x86-64/kernel-2.6.18-92.el5 (smp) and ran hackbench.

---<countsyscall.stp>--
#! stap
global counter

probe process("*").syscall {
        counter["entry"] <<< 1
}
probe process("*").syscall.return {
        counter["return"] <<< 1
}

probe end {
        foreach(s+ in counter) {
                printf("syscall %s : %d times\n",
                        s, @sum(counter[s]))
        }
}
---
And I got a kernel panic when I stopped the hackbench.
---
$ stap -v countsyscall.stp 
Pass 1: parsed user script and 43 library script(s) in 380usr/30sys/477real ms.
Pass 2: analyzed script: 3 probe(s), 0 function(s), 1 embed(s), 1 global(s) in
0usr/0sys/19real ms.
Pass 3: using cached
/home/mhiramat/.systemtap/cache/e5/stap_e5ae15296a82b7f59b933ee5fd04b233_626.c
Pass 4: using cached
/home/mhiramat/.systemtap/cache/e5/stap_e5ae15296a82b7f59b933ee5fd04b233_626.ko
Pass 5: starting run.
Unable to handle kernel NULL pointer dereference at 0000000000000004 RIP: 
 [<ffffffff885cd457>]
:stap_e5ae15296a82b7f59b933ee5fd04b233_626:__stp_utrace_task_finder_target_death+0x36/0x5f
PGD 0 
Oops: 0000 [1] SMP 
last sysfs file: /devices/pci0000:00/0000:00:03.0/0000:02:00.0/irq
CPU 1 
Modules linked in: stap_e5ae15296a82b7f59b933ee5fd04b233_626(U) ipt_MASQUERADE
iptable_nat ip_nat bridge autofs4 hidp rfcomm l2cap bluetooth sunrpc
ip_conntrack_netbios_ns ipt_REJECT xt_state ip_conntrack nfnetlink
iptable_filter ip_tables ip6t_REJECT xt_tcpudp ip6table_filter ip6_tables
x_tables cpufreq_ondemand dm_mirror dm_multipath dm_mod video sbs backlight
i2c_ec button battery asus_acpi acpi_memhotplug ac ipv6 xfrm_nalgo crypto_api lp
sr_mod cdrom snd_hda_intel snd_hda_codec snd_seq_dummy snd_seq_oss
snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss snd_pcm
parport_pc snd_timer parport snd shpchp i2c_nforce2 soundcore snd_page_alloc tg3
serio_raw sg pcspkr i2c_core k8temp hwmon k8_edac edac_mc sata_nv libata sd_mod
scsi_mod ext3 jbd uhci_hcd ohci_hcd ehci_hcd
Pid: 27096, comm: hackbench Tainted: G      2.6.18-92.el5 #1
RIP: 0010:[<ffffffff885cd457>]  [<ffffffff885cd457>]
:stap_e5ae15296a82b7f59b933ee5fd04b233_626:__stp_utrace_task_finder_target_death+0x36/0x5f
RSP: 0018:ffff81010dfedd18  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8100ccf3a860 RCX: ffffffff885d6480
RDX: 0000000000000000 RSI: ffff8100ccf3a860 RDI: ffff8100ccf3a860
RBP: ffff8100ccf3a860 R08: ffffffff885cd8cc R09: ffff8101042ebc80
R10: ffff81010dfedf58 R11: 0000000000000009 R12: ffff8100c2aa8b80
R13: ffff8100c2aa8b80 R14: ffff8100c2aa8ba0 R15: ffff81010b071780
FS:  00002ae8494a5890(0000) GS:ffff81010438e7c0(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000004 CR3: 0000000000201000 CR4: 00000000000006e0
Process hackbench (pid: 27096, threadinfo ffff81010dfec000, task ffff8100ccf3a860)
Stack:  ffff81010b0717c0 ffffffff800bcb30 ffff81012fc49a08 0000000000000010
 ffff8100ccf3a860 ffff8100c2aa8b80 ffff8100ccf3a998 ffff81010dfedef8
 ffff81010dfedf58 ffffffff80015747 0000000000000002 0000000000000000
Call Trace:
 [<ffffffff800bcb30>] utrace_report_death+0x7c/0x211
 [<ffffffff80015747>] do_exit+0x81c/0x8d0
 [<ffffffff80048a1c>] cpuset_exit+0x0/0x6c
 [<ffffffff8002b05b>] get_signal_to_deliver+0x42c/0x45a
 [<ffffffff8005aa43>] do_notify_resume+0x9c/0x7a9
 [<ffffffff885c9d73>] :stap_e5ae15296a82b7f59b933ee5fd04b233_626:str_eq_p+0xe/0x19
 [<ffffffff885c9fda>]
:stap_e5ae15296a82b7f59b933ee5fd04b233_626:__stp_pmap_set_sx+0x64/0xc5
 [<ffffffff885cfb60>]
:stap_e5ae15296a82b7f59b933ee5fd04b233_626:probe_1408+0x7f/0xcd
 [<ffffffff800bd33e>] utrace_report_syscall+0x6f/0x202
 [<ffffffff8005d32e>] int_signal+0x12/0x17


Code: 8b 40 04 85 c0 0f 94 c2 31 f6 41 ff d0 85 c0 74 cb 8b b3 24 
RIP  [<ffffffff885cd457>]
:stap_e5ae15296a82b7f59b933ee5fd04b233_626:__stp_utrace_task_finder_target_death+0x36/0x5f
 RSP <ffff81010dfedd18>
CR2: 0000000000000004
 <0>Kernel panic - not syncing: Fatal exception

-- 
           Summary: system-wide utrace syscall tracing will cause kernel
                    panic by hackbench.
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: uprobes
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: mhiramat at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=6842

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