Date:   Fri, 15 Mar 2019 23:27:12 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        VDR User <user.vdr@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: r8169 driver from kernel 5.0 crashing - napi_consume_skb

On 15.03.2019 23:09, Alexander Duyck wrote:
> On Fri, 2019-03-15 at 21:46 +0100, Heiner Kallweit wrote:
>> On 15.03.2019 21:40, Alexander Duyck wrote:
>>> On Fri, 2019-03-15 at 21:26 +0100, Heiner Kallweit wrote:
>>>> On 15.03.2019 21:09, VDR User wrote:
>>>>>>>>> Thanks for the additional info and for testing 4.20.15.
>>>>>>>>> To rule out that the issue is caused by a regression in network or
>>>>>>>>> some other subsystem: Can you take the r8169.c from 4.20.15 and test
>>>>>>>>> it on top of 5.0?
>>>>>>>>> Meanwhile I'll look at the changes in the driver between 4.20 and 5.0.
>>>>>>>>
>>>>>>>> Sure, no problem! I'll copy the driver & recompile now actually.
>>>>>>>> Hopefully there aren't a ton of changes to r8169.c to sift through and
>>>>>>>> the cause isn't good at hiding itself!
>>>>>>>>
>>>>>>> I checked the driver changes new in 5.0 and there are very few
>>>>>>> functional changes. You could try to revert the following:
>>>>>>>
>>>>>>> 5317d5c6d47e ("r8169: use napi_consume_skb where possible")
>>>>>>
>>>>>> Will do, and fwiw, while I haven't been able to do tons of testing
>>>>>> today, I haven't been able to trigger the crash after replacing
>>>>>> 5.0.0's r8169.c with 4.20.15's r8169.c this morning. I'll restore the
>>>>>> file and revert the change you mentioned, and report back my findings.
>>>>>
>>>>> Heiner,
>>>>>
>>>>> After going back to vanilla kernel 5.0 and then reverting 5317d5c6d47e
>>>>> ("r8169: use napi_consume_skb where possible"), I so far have not had
>>>>> any crashes after transferring roughly 30GB back & forth. I'm not
>>>>> completely confident yet the crash is resolve with that revert and
>>>>> will continue to do further testing throughout the weekend as well.
>>>>> What confidence level do you have that 5317d5c6d47e is the culprit at
>>>>> this point?
>>>>>
>>>> Good, thanks for testing. I simply see no other change since 4.20 that
>>>> could cause these symptoms.
>>>> Using napi_consume_skb() at this place in r8169.c looks safe to me.
>>>> Option 1 is that I miss something, option 2 is that there's an issue
>>>> in the NAPI subsystem. However in the latter case I assume at least
>>>> the Mellanox and/or Intel guys would have observed the same issue
>>>> on their respective CI systems.
>>>> Let me add Alexander, maybe he can provide a hint before we go and
>>>> revert the change.
>>>
>>> Do you have the crash log? I'd be curious what the issue is we are
>>> seeing.
>>>
>>> I agree I can't see anything obvious, but it is possible that we may be
>>> running into something we hadn't seen with the Intel and Mellanox
>>> parts.
>>>
>>> - Alex
>>>
>>>
>> Crash may have been the wrong word, network becomes unresponsive
>> and the user sees the generic transmit queue timeout.
>> Let me quote his original mail:
>>
>> ------------------------------------------------------------------------
>>
>> Hi, after updating to kernel 5.0, the nic driver (r8169) has been
>> crashing whenever I start using heavy traffic on it (for example,
>> xferring large files to the box across my lan). The destination
>> harddrive may be sleeping and need to spin-up, or not, but the box
>> itself does not suspend/hibernate. The nic becomes completely
>> unresponsive and all connections to the box drop. After what I think
>> is several minutes, the connection comes back to life. The problem
>> happens consistently but seemingly not consistently at the same point.
>> For example, I can xfer a few 4gb files and it will crash at around
>> 2-3gb on the first file. The next time it might not crash until 2-3gb
>> on the second file.Prior to kernel 5.0 I was using 4.19.12 and this
>> problem didn't occur. I have since downgraded back to 4.19.12 pending
>> what response this post gets.
>>
>> Thanks for any help or assistance on how to proceed!
>> -Derek
>>
>> NOTE: I'm not subscribed to this mailing list so please CC me on any replies!
>>
>> The nic is on-board ECS A75F-A:
>> 04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
>> RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
>>         Subsystem: Elitegroup Computer Systems RTL8111/8168/8411 PCI
>> Express Gigabit Ethernet Controller
>>         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop-
>> ParErr- Stepping- SERR- FastB2B- DisINTx+
>>         Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort-
>> <TAbort- <MAbort- >SERR- <PERR- INTx-
>>         Latency: 0, Cache Line Size: 64 bytes
>>         Interrupt: pin A routed to IRQ 17
>>         Region 0: I/O ports at c000 [size=256]
>>         Region 2: Memory at d0004000 (64-bit, prefetchable) [size=4K]
>>         Region 4: Memory at d0000000 (64-bit, prefetchable) [size=16K]
>>         Capabilities: <access denied>
>>         Kernel driver in use: r8169
>>
>> I see the following in the syslog:
>>
>> [164572.785517] ------------[ cut here ]------------
>> [164572.785595] NETDEV WATCHDOG: enp4s0 (r8169): transmit queue 0 timed out
>> [164572.785677] WARNING: CPU: 1 PID: 0 at net/sched/sch_generic.c:461
>> dev_watchdog+0x1bb/0x1e0
>> [164572.785730] Modules linked in: snd_hda_codec_realtek
>> snd_hda_codec_generic snd_hda_codec_hdmi ohci_pci snd_hda_intel
>> snd_hda_codec snd_hwdep xhci_pci ehci_pci ohci_hcd xhci_hcd ehci_hcd
>> usbcore usb_common snd_hda_core snd_pcm snd_timer snd soundcore nfsd
>> auth_rpcgss oid_registry lockd grace sunrpc ip_tables x_tables ipv6
>> [164572.785807] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.0.0-amd #2
>> [164572.785842] Hardware name: ECS A75F-A/A75F-A, BIOS 4.6.5 09/14/2011
>> [164572.785878] EIP: dev_watchdog+0x1bb/0x1e0
>> [164572.785912] Code: 8b 50 3c 89 f8 e8 3d aa 0a 00 8b 7e f4 eb a4 89
>> f8 c6 05 e7 1c 6d c1 01 e8 72 4f fd ff 53 50 57 68 78 05 66 c1 e8 25
>> ad ba ff <0f> 0b 83 c4 10 eb c9 eb 1c 8d b4 26 00 00 00 00 8d b4 26 00
>> 00 00
>> [164572.785963] EAX: 0000003b EBX: 00000000 ECX: 00000800 EDX: 00000103
>> [164572.785998] ESI: f4cbc264 EDI: f4cbc000 EBP: f4c99f74 ESP: f4c99f4c
>> [164572.786033] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00210296
>> [164572.786067] CR0: 80050033 CR2: 020dc000 CR3: 2b80b000 CR4: 00000690
>> [164572.786102] Call Trace:
>> [164572.786135]  <SOFTIRQ>
>> [164572.786168]  ? qdisc_put_unlocked+0x40/0x40
>> [164572.786203]  call_timer_fn+0x19/0xa0
>> [164572.786237]  run_timer_softirq+0x337/0x380
>> [164572.786270]  ? qdisc_put_unlocked+0x40/0x40
>> [164572.786302]  ? rcu_process_callbacks+0xcb/0x380
>> [164572.786337]  __do_softirq+0xd6/0x21c
>> [164572.786370]  ? __irqentry_text_end+0x18/0x18
>> [164572.786404]  call_on_stack+0x10/0x60
>> [164572.786435]  </SOFTIRQ>
>> [164572.786467]  ? irq_exit+0x91/0xc0
>> [164572.786495]  ? smp_apic_timer_interrupt+0x56/0xa0
>> [164572.786525]  ? apic_timer_interrupt+0xd5/0xdc
>> [164572.786555]  ? acpi_idle_enter_s2idle+0x60/0x60
>> [164572.786584]  ? cpuidle_enter_state+0x122/0x360
>> [164572.786614]  ? tick_nohz_idle_stop_tick+0x27b/0x2a0
>> [164572.786644]  ? cpuidle_enter+0xf/0x20
>> [164572.786673]  ? call_cpuidle+0x1c/0x40
>> [164572.786701]  ? do_idle+0x1e6/0x220
>> [164572.786730]  ? cpu_startup_entry+0x25/0x40
>> [164572.786758]  ? start_secondary+0x1a5/0x220
>> [164572.786787]  ? startup_32_smp+0x15f/0x164
>> [164572.786816] ---[ end trace 662a5195537dbad8 ]---
>>
> 
> Okay, the patch suggested doesn't make much sense for the issue
> described. I was expecting to see something that at least pointed to
> the NAPI logic, and I don't see anything doing as such.
> 
According to the tests done so far replacing napi_consume_skb()
with dev_consume_skb_any() seems to reliably avoid the issue.
If there really should be an issue with irq/ring management,
then the question would be why it's not trigger with
dev_consume_skb_any().

> The issue looks like a problem of the ring being stopped at the QDISC
> layer for an extended period of time. Basically somebody called
> netif_stop_queue and then never got around to calling netif_wake_queue
> to let the ring resume transmitting.
> 
> My first thoughts would be to look at an interrupt that are getting
> masked and lost, or some ring accounting issue where you are flagging
> the ring to stop and then not waking it up due to a math or logic error
> somewhere. It looks like there were multiple patches messing with these
> sort of items between 4.20 and 5.0 so I would recommend looking there.
> 
> - Alex
> 
Heiner
> 
> 

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