On Fri, Jun 27, 2014 at 3:14 PM, Djalal Harouni <tix...@opendz.org> wrote:
> On Fri, Jun 27, 2014 at 02:28:56PM -0700, Greg KH wrote:
>> On Fri, Jun 27, 2014 at 10:19:03PM +0100, Djalal Harouni wrote:
>> > On Fri, Jun 27, 2014 at 12:23:05PM +0100, Djalal Harouni wrote:
>> > > On Fri, Jun 27, 2014 at 01:04:00PM +0200, Daniel Mack wrote:
>> > > > On 06/27/2014 12:51 PM, Djalal Harouni wrote:
>> > > > > Just to let you know that I did notice a regression by ~70% when 
>> > > > > running
>> > > > > test-kdbus-benchmark on a kvm guest (that's what I've under hands 
>> > > > > now)
>> > > > >
>> > > > > I know sorry, but still a kdbus on kvm is a valid case, I don't know 
>> > > > > if
>> > > > > this affects real machine or only kvm guests will be able to confirm 
>> > > > > it
>> > > > > next week unless someone do!
>> > > > >
>> > > > > If you are able to test it in a real machine and confirm that it 
>> > > > > affects
>> > > > > them too, thank you!
>> > > > > I've managed to bisect this to:
>> > > > > 3.15.0-rc1 good
>> > > > > 3.15.0-rc5 bad
>> > > > >
>> > > > > I Will continue later this day!
>> > > >
>> > > > Please do. I'm not currently aware of such a regression. What about
>> > > > 3.16-rc2?
>> > A bit late, sorry!
>> >
>> > I was wrong on the 3.15.0-rc5 sorry that was a fedora rawhide kernel got
>> > confused by the naming and 'rc5'... but yes fedora rawhide affected! so
>> > something backported perhaps...
>> >
>> >
>> > Anyway for upstream tests:
>> >
>> > 3.15.0-rc5 and 3.15.0-rc7 are good
>> >
>> > 3.16-rc1 and 3.16-rc2 are bad
>> >
>> > So I confirm there is a regression somewhere.
>>
>> Can you run 'git bisect' on the kernel tree to try to track down the
>> problem commit?
> Yes of course! I'm planning to do so
>
> Thanks!
>

Was going to try to repro this perf regression as well, but instead got
kdbus to oops (via test-kdbus-benchmark):

$ test/test-kdbus-benchmark 
-- opening /dev/kdbus/control
-- creating bus '1000-testbus'
-- opening bus connection /dev/kdbus/1000-testbus/bus
-- Our peer ID for /dev/kdbus/1000-testbus/bus: 1 -- bus uuid:
'b65bfdd23d3e4696aae2992a0857aa33'
-- opening bus connection /dev/kdbus/1000-testbus/bus
-- Our peer ID for /dev/kdbus/1000-testbus/bus: 2 -- bus uuid:
'b65bfdd23d3e4696aae2992a0857aa33'
name_acquire(): flags after call: 0x0                                           
                                                     
Killed
$

[   32.853967] kdbus: initialized
[   33.557785] BUG: unable to handle kernel NULL pointer dereference at         
  (null)
[   33.557819] IP: [<          (null)>]           (null)
[   33.557837] PGD c58a5067 PUD c81cd067 PMD 0
[   33.557856] Oops: 0010 [#1] SMP
[   33.557870] Modules linked in: kdbus(O) snd_hda_codec_hdmi tun hid_generic 
snd_hda_codec_realtek snd_hda_codec_generic usbhid hid kvm_amd kvm 
crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel aes_x86_64 lrw 
gf128mul glue_helper ablk_helper cryptd snd_hda_intel snd_hda_controller radeon 
microcode snd_hda_codec snd_hwdep broadcom snd_pcm snd_timer serio_raw tg3 
fam15h_power snd ttm soundcore libphy edac_core i2c_piix4 edac_mce_amd k10temp 
tpm_tis tpm acpi_cpufreq wmi evdev processor usbip_host(C) usbip_core(C) ext4 
crc16 jbd2 mbcache sd_mod ata_generic pata_acpi crc_t10dif crct10dif_common 
ahci pata_jmicron libahci pata_atiixp crc32c_intel ehci_pci ehci_hcd xhci_hcd 
libata firewire_ohci usbcore scsi_mod usb_common firewire_core crc_itu_t i915 
video intel_gtt i2c_algo_bit drm_kms_helper
[   33.558231]  drm i2c_core e1000e ptp pps_core ipmi_poweroff ipmi_msghandler 
button
[   33.558267] CPU: 1 PID: 1393 Comm: test-kdbus-benc Tainted: G         C O  
3.16.0-rc2-ec2-00222-g3493860 #1
[   33.558335] task: ffff8803e7811d80 ti: ffff8800c82cc000 task.ti: 
ffff8800c82cc000
[   33.558364] RIP: 0010:[<0000000000000000>]  [<          (null)>]           
(null)
[   33.558398] RSP: 0018:ffff8800c82cfe40  EFLAGS: 00010246
[   33.558419] RAX: ffffffff81636400 RBX: ffff880406dcfe40 RCX: 0000000000000000
[   33.558447] RDX: 0000000000000001 RSI: ffff8800c82cfe88 RDI: ffff8800c82cfe98
[   33.558475] RBP: ffff8800c82cfe78 R08: 00007fff80d23810 R09: ffff8803f9d5cc00
[   33.558503] R10: ffff8803e7811d80 R11: 0000000000000246 R12: ffff8800c82cfe98
[   33.558532] R13: ffff880406dcfe48 R14: ffff8800c82cfe88 R15: 0000000000000001
[   33.558566] FS:  00007f97e69bf700(0000) GS:ffff88042dc40000(0000) 
knlGS:0000000000000000
[   33.558595] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[   33.558616] CR2: 0000000000000000 CR3: 0000000036e20000 CR4: 00000000000407e0
[   33.558642] Stack:
[   33.558650]  ffffffffa11f45d6 0000000000000000 ffff8800c82cff50 
0000000000000010
[   33.558681]  00007fff80d23800 ffff8800c82cff50 0000000000000000 
ffff8800c82cfef8
[   33.558712]  ffffffff811d386a 00007fff80d23800 0000000000000010 
ffff8803f9d5d400
[   33.558743] Call Trace:
[   33.558757]  [<ffffffffa11f45d6>] ? kdbus_memfd_writev+0x66/0xa0 [kdbus]
[   33.558785]  [<ffffffff811d386a>] do_sync_write+0x5a/0x90
[   33.558806]  [<ffffffff811d4071>] vfs_write+0x151/0x200
[   33.558827]  [<ffffffff811d4bb6>] SyS_write+0x46/0xc0
[   33.558847]  [<ffffffff81105eb6>] ? __audit_syscall_exit+0x236/0x2e0
[   33.558872]  [<ffffffff8152faed>] system_call_fastpath+0x1a/0x1f
[   33.558894] Code:  Bad RIP value.
[   33.558910] RIP  [<          (null)>]           (null)
[   33.558930]  RSP <ffff8800c82cfe40>
[   33.558943] CR2: 0000000000000000
[   33.569387] ---[ end trace e8d6c50c5ef168aa ]---

Any ideas?
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