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Message-ID: <8119066974f099aa11f08a4dad3653ac0ba32cd6.camel@gmx.de>
Date: Wed, 24 Nov 2021 18:20:40 +0100
From: Stefan Dietrich <roots@....de>
To: Greg KH <greg@...ah.com>, netdev@...r.kernel.org
Cc: stable@...r.kernel.org, regressions@...ts.linux.dev
Subject: Re: [REGRESSION] Kernel 5.15 reboots / freezes upon ifup/ifdown
Hi all,
six exciting hours and a lot of learning later, here it is.
Symptomatically, the critical commit appears for me between 5.14.21-
051421-generic and 5.15.0-051500rc2-generic - I did not find an amd64
build for rc1.
Please see the git-bisect output below and let me know how I may
further assist in debugging!
Cheers,
Stefan
a90ec84837325df4b9a6798c2cc0df202b5680bd is the first bad commit
commit a90ec84837325df4b9a6798c2cc0df202b5680bd
Author: Vinicius Costa Gomes <vinicius.gomes@...el.com>
Date: Mon Jul 26 20:36:57 2021 -0700
igc: Add support for PTP getcrosststamp()
i225 supports PCIe Precision Time Measurement (PTM), allowing us to
support the PTP_SYS_OFFSET_PRECISE ioctl() in the driver via the
getcrosststamp() function.
The easiest way to expose the PTM registers would be to configure
the PTM
dialogs to run periodically, but the PTP_SYS_OFFSET_PRECISE ioctl()
semantics are more aligned to using a kind of "one-shot" way of
retrieving
the PTM timestamps. But this causes a bit more code to be written:
the
trigger registers for the PTM dialogs are not cleared
automatically.
i225 can be configured to send "fake" packets with the PTM
information, adding support for handling these types of packets is
left for the future.
PTM improves the accuracy of time synchronization, for example,
using
phc2sys, while a simple application is sending packets as fast as
possible. First, without .getcrosststamp():
phc2sys[191.382]: enp4s0 sys offset -959 s2 freq -454
delay 4492
phc2sys[191.482]: enp4s0 sys offset 798 s2 freq +1015
delay 4069
phc2sys[191.583]: enp4s0 sys offset 962 s2 freq +1418
delay 3849
phc2sys[191.683]: enp4s0 sys offset 924 s2 freq +1669
delay 3753
phc2sys[191.783]: enp4s0 sys offset 664 s2 freq +1686
delay 3349
phc2sys[191.883]: enp4s0 sys offset 218 s2 freq +1439
delay 2585
phc2sys[191.983]: enp4s0 sys offset 761 s2 freq +2048
delay 3750
phc2sys[192.083]: enp4s0 sys offset 756 s2 freq +2271
delay 4061
phc2sys[192.183]: enp4s0 sys offset 809 s2 freq +2551
delay 4384
phc2sys[192.283]: enp4s0 sys offset -108 s2 freq +1877
delay 2480
phc2sys[192.383]: enp4s0 sys offset -1145 s2 freq +807
delay 4438
phc2sys[192.484]: enp4s0 sys offset 571 s2 freq +2180
delay 3849
phc2sys[192.584]: enp4s0 sys offset 241 s2 freq +2021
delay 3389
phc2sys[192.684]: enp4s0 sys offset 405 s2 freq +2257
delay 3829
phc2sys[192.784]: enp4s0 sys offset 17 s2 freq +1991
delay 3273
phc2sys[192.884]: enp4s0 sys offset 152 s2 freq +2131
delay 3948
phc2sys[192.984]: enp4s0 sys offset -187 s2 freq +1837
delay 3162
phc2sys[193.084]: enp4s0 sys offset -1595 s2 freq +373
delay 4557
phc2sys[193.184]: enp4s0 sys offset 107 s2 freq +1597
delay 3740
phc2sys[193.284]: enp4s0 sys offset 199 s2 freq +1721
delay 4010
phc2sys[193.385]: enp4s0 sys offset -169 s2 freq +1413
delay 3701
phc2sys[193.485]: enp4s0 sys offset -47 s2 freq +1484
delay 3581
phc2sys[193.585]: enp4s0 sys offset -65 s2 freq +1452
delay 3778
phc2sys[193.685]: enp4s0 sys offset 95 s2 freq +1592
delay 3888
phc2sys[193.785]: enp4s0 sys offset 206 s2 freq +1732
delay 4445
phc2sys[193.885]: enp4s0 sys offset -652 s2 freq +936
delay 2521
phc2sys[193.985]: enp4s0 sys offset -203 s2 freq +1189
delay 3391
phc2sys[194.085]: enp4s0 sys offset -376 s2 freq +955
delay 2951
phc2sys[194.185]: enp4s0 sys offset -134 s2 freq +1084
delay 3330
phc2sys[194.285]: enp4s0 sys offset -22 s2 freq +1156
delay 3479
phc2sys[194.386]: enp4s0 sys offset 32 s2 freq +1204
delay 3602
phc2sys[194.486]: enp4s0 sys offset 122 s2 freq +1303
delay 3731
Statistics for this run (total of 2179 lines), in nanoseconds:
average: -1.12
stdev: 634.80
max: 1551
min: -2215
With .getcrosststamp() via PCIe PTM:
phc2sys[367.859]: enp4s0 sys offset 6 s2 freq +1727
delay 0
phc2sys[367.959]: enp4s0 sys offset -2 s2 freq +1721
delay 0
phc2sys[368.059]: enp4s0 sys offset 5 s2 freq +1727
delay 0
phc2sys[368.160]: enp4s0 sys offset -1 s2 freq +1723
delay 0
phc2sys[368.260]: enp4s0 sys offset -4 s2 freq +1719
delay 0
phc2sys[368.360]: enp4s0 sys offset -5 s2 freq +1717
delay 0
phc2sys[368.460]: enp4s0 sys offset 1 s2 freq +1722
delay 0
phc2sys[368.560]: enp4s0 sys offset -3 s2 freq +1718
delay 0
phc2sys[368.660]: enp4s0 sys offset 5 s2 freq +1725
delay 0
phc2sys[368.760]: enp4s0 sys offset -1 s2 freq +1721
delay 0
phc2sys[368.860]: enp4s0 sys offset 0 s2 freq +1721
delay 0
phc2sys[368.960]: enp4s0 sys offset 0 s2 freq +1721
delay 0
phc2sys[369.061]: enp4s0 sys offset 4 s2 freq +1725
delay 0
phc2sys[369.161]: enp4s0 sys offset 1 s2 freq +1724
delay 0
phc2sys[369.261]: enp4s0 sys offset 4 s2 freq +1727
delay 0
phc2sys[369.361]: enp4s0 sys offset 8 s2 freq +1732
delay 0
phc2sys[369.461]: enp4s0 sys offset 7 s2 freq +1733
delay 0
phc2sys[369.561]: enp4s0 sys offset 4 s2 freq +1733
delay 0
phc2sys[369.661]: enp4s0 sys offset 1 s2 freq +1731
delay 0
phc2sys[369.761]: enp4s0 sys offset 1 s2 freq +1731
delay 0
phc2sys[369.861]: enp4s0 sys offset -5 s2 freq +1725
delay 0
phc2sys[369.961]: enp4s0 sys offset -4 s2 freq +1725
delay 0
phc2sys[370.062]: enp4s0 sys offset 2 s2 freq +1730
delay 0
phc2sys[370.162]: enp4s0 sys offset -7 s2 freq +1721
delay 0
phc2sys[370.262]: enp4s0 sys offset -3 s2 freq +1723
delay 0
phc2sys[370.362]: enp4s0 sys offset 1 s2 freq +1726
delay 0
phc2sys[370.462]: enp4s0 sys offset -3 s2 freq +1723
delay 0
phc2sys[370.562]: enp4s0 sys offset -1 s2 freq +1724
delay 0
phc2sys[370.662]: enp4s0 sys offset -4 s2 freq +1720
delay 0
phc2sys[370.762]: enp4s0 sys offset -7 s2 freq +1716
delay 0
phc2sys[370.862]: enp4s0 sys offset -2 s2 freq +1719
delay 0
Statistics for this run (total of 2179 lines), in nanoseconds:
average: 0.14
stdev: 5.03
max: 48
min: -27
For reference, the statistics for runs without PCIe congestion show
that the improvements from enabling PTM are less dramatic. For two
runs of 16466 entries:
without PTM: avg -0.04 stdev 10.57 max 39 min -42
with PTM: avg 0.01 stdev 4.20 max 19 min -16
One possible explanation is that when PTM is not enabled, and
there's a lot
of traffic in the PCIe fabric, some register reads will take more
time
than the others because of congestion on the PCIe fabric.
When PTM is enabled, even if the PTM dialogs take more time to
complete under heavy traffic, the time measurements do not depend
on
the time to read the registers.
This was implemented following the i225 EAS version 0.993.
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@...ux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
drivers/net/ethernet/intel/igc/igc.h | 1 +
drivers/net/ethernet/intel/igc/igc_defines.h | 31 +++++
drivers/net/ethernet/intel/igc/igc_ptp.c | 179
+++++++++++++++++++++++++++
drivers/net/ethernet/intel/igc/igc_regs.h | 23 ++++
4 files changed, 234 insertions(+)
On Wed, 2021-11-24 at 08:33 +0100, Greg KH wrote:
> On Wed, Nov 24, 2021 at 08:28:39AM +0100, Stefan Dietrich wrote:
> > Summary: When attempting to rise or shut down a NIC manually or via
> > network-manager under 5.15, the machine reboots or freezes.
> >
> > Occurs with: 5.15.4-051504-generic and earlier 5.15 mainline (
> > https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.15.4/) as well as
> > liquorix flavours.
> > Does not occur with: 5.14 and 5.13 (both with various flavours)
>
> Can you use 'git bisect' between 5.14 and 5.15 to find the problem
> commit?
>
> thanks,
>
> greg k-h
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