lkml.org 
[lkml]   [2015]   [Sep]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: perf: fuzzer PEBS record without PEBS event! crash
On Mon, 7 Sep 2015, Stephane Eranian wrote:

> On Mon, Sep 7, 2015 at 2:44 AM, Vince Weaver <vincent.weaver@maine.edu> wrote:
> > On Sun, 6 Sep 2015, Stephane Eranian wrote:
> >
> >> > [ 1800.285152] ------------[ cut here ]------------
> >> > [ 1800.290757] WARNING: CPU: 0 PID: 0 at arch/x86/kernel/cpu/perf_event_intel_ds.c:1210 intel_pmu_drain_pebs_nhm+0x305/0x320()
> >> > [ 1800.303301] PEBS record without PEBS event! status=2 pebs_enabled=1 active_mask=200000000
> >> > [ 1800.311916] Modules linked in: binfmt_misc intel_rapl iosf_mbi x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_hdmi hmac drbg ansi_cprng i915 aesni_intel aes_x86_64 snd_hda_codec_realtek snd_hda_codec_generic lrw snd_hda_intel snd_hda_codec iTCO_wdt gf128mul drm_kms_helper snd_hda_core ppdev iTCO_vendor_support evdev glue_helper ablk_helper cryptd parport_pc snd_hwdep snd_pcm snd_timer psmouse tpm_tis tpm drm i2c_algo_bit sg parport snd pcspkr video serio_raw processor soundcore mei_me lpc_ich mfd_core mei i2c_i801 wmi button battery sr_mod sd_mod cdrom ehci_pci ehci_hcd xhci_pci xhci_hcd ahci libahci libata e1000e ptp usbcore crc32c_intel scsi_mod pps_core usb_common fan thermal
> >> > [ 1800.390813] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 4.2.0+ #173
> >> > [ 1800.399488] Hardware name: LENOVO 10AM000AUS/SHARKBAY, BIOS FBKT72AUS 01/26/2014
> >> > [ 1800.408243] ffffffff81a0d828 ffff88011ea03aa8 ffffffff8169da0c ffff88011ea03af0
> >> > [ 1800.417089] ffff88011ea03ae0 ffffffff8106e812 0000000000000001 ffff880119000000
> >> > [ 1800.426024] ffff88011ea0c120 ffff88011900ffc0 ffff880119000000 ffff88011ea03b40
> >> > [ 1800.434946] Call Trace:
> >> > [ 1800.438453] <IRQ> [<ffffffff8169da0c>] dump_stack+0x44/0x55
> >> > [ 1800.445504] [<ffffffff8106e812>] warn_slowpath_common+0x82/0xc0
> >> > [ 1800.452832] [<ffffffff8106e89c>] warn_slowpath_fmt+0x4c/0x50
> >> > [ 1800.459879] [<ffffffff8102f7d5>] intel_pmu_drain_pebs_nhm+0x305/0x320
> >> > [ 1800.467725] [<ffffffff810b6b69>] ? __lock_acquire.isra.31+0x349/0xfc0
> >> > [ 1800.475613] [<ffffffff8102ec38>] intel_pmu_drain_pebs_buffer+0x18/0x20
> >>
> >>
> >> What would help here is if you could get the source line number. You can do that
> >> with gdb:
> >> gdb vmlinux
> >> (gdb) info line *0xffffffff8102ec38
> >
> > (gdb) info line *0xffffffff8102ec38
> > Line 567 of "arch/x86/kernel/cpu/perf_event_intel_ds.c"
> > starts at address 0xffffffff8102ec38 <intel_pmu_drain_pebs_buffer+24>
> > and ends at 0xffffffff8102ec40 <release_pebs_buffer>.
> >
> > Line 567 isn't that helpful, it's just the last line of
> > intel_pmu_drain_pebs_buffer() but that's possibly because I have done a
> > git pull since the time I built the kernel so the source tree doesn't
> > match up.
> >
> Do it again with the matching source tree. Addresses change all the time.

I re-compiled with current git, and the source matches the kernel exactly
now. I managed to trigger the warning again (though it didn't trigger a
crash yet). Still got line 567

[ 6890.067085] WARNING: CPU: 7 PID: 7 at arch/x86/kernel/cpu/perf_event_intel_ds.c:1210 intel_pmu_drain_pebs_nhm+0x305/0x320()
[ 6890.078963] PEBS record without PEBS event! status=0 pebs_enabled=1 active_mask=200000001
[ 6890.199394] Call Trace:
[ 6890.202024] [<ffffffff8169ffe0>] dump_stack+0x44/0x55
[ 6890.207516] [<ffffffff8106e8b2>] warn_slowpath_common+0x82/0xc0
[ 6890.213990] [<ffffffff8106e93c>] warn_slowpath_fmt+0x4c/0x50
[ 6890.220128] [<ffffffff8102f7d5>] intel_pmu_drain_pebs_nhm+0x305/0x320
[ 6890.227092] [<ffffffff8102ec38>] intel_pmu_drain_pebs_buffer+0x18/0x20

(gdb) info line *0xffffffff8102ec38
Line 567 of "arch/x86/kernel/cpu/perf_event_intel_ds.c"
starts at address 0xffffffff8102ec38 <intel_pmu_drain_pebs_buffer+24>
and ends at 0xffffffff8102ec40 <release_pebs_buffer>.


which is

562:static inline void intel_pmu_drain_pebs_buffer(void)
563:{
564: struct pt_regs regs;
565:
566: x86_pmu.drain_pebs(&regs);
567: }

which seems odd, though I guess because it is inlined?

Vince


\
 
 \ /
  Last update: 2015-09-08 17:41    [W:0.069 / U:0.036 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site