Re: aacraid: Regression in 4.14.56 with *genirq/affinity: assign vectors to all possible CPUs*

[Paul Menzel <pmenzel+linux-scsi@molgen.mpg.de>]

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Dear Ming, dear Raghava, dear Dave,


On 08/16/18 19:09, Paul Menzel wrote:

> On 08/13/18 05:32, Ming Lei wrote:
>> On Sat, Aug 11, 2018 at 03:50:21PM +0200, Greg Kroah-Hartman wrote:
>>> On Sat, Aug 11, 2018 at 10:14:18AM +0200, Paul Menzel wrote:
> 
>>>> Am 10.08.2018 um 17:55 schrieb Greg Kroah-Hartman:
>>>>> On Fri, Aug 10, 2018 at 04:11:23PM +0200, Paul Menzel wrote:
>>>>
>>>>>> On 08/10/18 15:36, Greg Kroah-Hartman wrote:
>>>>>>> On Fri, Aug 10, 2018 at 03:21:52PM +0200, Paul Menzel wrote:
> 
>>>>>>>> Commit ef86f3a7 (genirq/affinity: assign vectors to all possible CPUs) added
>>>>>>>> for Linux 4.14.56 causes the aacraid module to not detect the attached devices
>>>>>>>> anymore on a Dell PowerEdge R720 with two six core 24x E5-2630 @ 2.30GHz.
>>>>>>>>
>>>>>>>> ```
>>>>>>>> $ dmesg | grep raid
>>>>>>>> [    0.269768] raid6: sse2x1   gen()  7179 MB/s
>>>>>>>> [    0.290069] raid6: sse2x1   xor()  5636 MB/s
>>>>>>>> [    0.311068] raid6: sse2x2   gen()  9160 MB/s
>>>>>>>> [    0.332076] raid6: sse2x2   xor()  6375 MB/s
>>>>>>>> [    0.353075] raid6: sse2x4   gen() 11164 MB/s
>>>>>>>> [    0.374064] raid6: sse2x4   xor()  7429 MB/s
>>>>>>>> [    0.379001] raid6: using algorithm sse2x4 gen() 11164 MB/s
>>>>>>>> [    0.386001] raid6: .... xor() 7429 MB/s, rmw enabled
>>>>>>>> [    0.391008] raid6: using ssse3x2 recovery algorithm
>>>>>>>> [    3.559682] megaraid cmm: 2.20.2.7 (Release Date: Sun Jul 16 00:01:03 EST 2006)
>>>>>>>> [    3.570061] megaraid: 2.20.5.1 (Release Date: Thu Nov 16 15:32:35 EST 2006)
>>>>>>>> [   10.725767] Adaptec aacraid driver 1.2.1[50834]-custom
>>>>>>>> [   10.731724] aacraid 0000:04:00.0: can't disable ASPM; OS doesn't have ASPM control
>>>>>>>> [   10.743295] aacraid: Comm Interface type3 enabled
>>>>>>>> $ lspci -nn | grep Adaptec
>>>>>>>> 04:00.0 Serial Attached SCSI controller [0107]: Adaptec Series 8 12G SAS/PCIe 3 [9005:028d] (rev 01)
>>>>>>>> 42:00.0 Serial Attached SCSI controller [0107]: Adaptec Smart Storage PQI 12G SAS/PCIe 3 [9005:028f] (rev 01)
>>>>>>>> ```
>>>>>>>>
>>>>>>>> But, it still works with a Dell PowerEdge R715 with two eight core AMD
>>>>>>>> Opteron 6136, the card below.
>>>>>>>>
>>>>>>>> ```
>>>>>>>> $ lspci -nn | grep Adaptec
>>>>>>>> 22:00.0 Serial Attached SCSI controller [0107]: Adaptec Series 8 12G SAS/PCIe 3 [9005:028d] (rev 01)
>>>>>>>> ```
>>>>>>>>
>>>>>>>> Reverting the commit fixes the issue.
>>>>>>>>
>>>>>>>> commit ef86f3a72adb8a7931f67335560740a7ad696d1d
>>>>>>>> Author: Christoph Hellwig <hch@lst.de>
>>>>>>>> Date:   Fri Jan 12 10:53:05 2018 +0800
>>>>>>>>
>>>>>>>>      genirq/affinity: assign vectors to all possible CPUs
>>>>>>>>      commit 84676c1f21e8ff54befe985f4f14dc1edc10046b upstream.
>>>>>>>>      Currently we assign managed interrupt vectors to all present CPUs.  This
>>>>>>>>      works fine for systems were we only online/offline CPUs.  But in case of
>>>>>>>>      systems that support physical CPU hotplug (or the virtualized version of
>>>>>>>>      it) this means the additional CPUs covered for in the ACPI tables or on
>>>>>>>>      the command line are not catered for.  To fix this we'd either need to
>>>>>>>>      introduce new hotplug CPU states just for this case, or we can start
>>>>>>>>      assining vectors to possible but not present CPUs.
>>>>>>>>      Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
>>>>>>>>      Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
>>>>>>>>      Tested-by: Stefan Haberland <sth@linux.vnet.ibm.com>
>>>>>>>>      Fixes: 4b855ad37194 ("blk-mq: Create hctx for each present CPU")
>>>>>>>>      Cc: linux-kernel@vger.kernel.org
>>>>>>>>      Cc: Thomas Gleixner <tglx@linutronix.de>
>>>>>>>>      Signed-off-by: Christoph Hellwig <hch@lst.de>
>>>>>>>>      Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>>>>>>>      Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>>>>>>>
>>>>>>>> The problem doesn’t happen with Linux 4.17.11, so there are commits in
>>>>>>>> Linux master fixing this. Unfortunately, my attempts to find out failed.
>>>>>>>>
>>>>>>>> I was able to cherry-pick the three commits below on top of 4.14.62,
>>>>>>>> but the problem persists.
>>>>>>>>
>>>>>>>> 6aba81b5a2f5 genirq/affinity: Don't return with empty affinity masks on error
>>>>>>>> 355d7ecdea35 scsi: hpsa: fix selection of reply queue
>>>>>>>> e944e9615741 scsi: virtio_scsi: fix IO hang caused by automatic irq vector affinity
>>>>>>>>
>>>>>>>> Trying to cherry-pick the commits below, referencing the commit
>>>>>>>> in question, gave conflicts.
>>>>>>>>
>>>>>>>> 1. adbe552349f2 scsi: megaraid_sas: fix selection of reply queue
>>>>>>>> 2. d3056812e7df genirq/affinity: Spread irq vectors among present CPUs as far as possible
>>>>>>>>
>>>>>>>> To avoid further trial and error with the server with a slow firmware,
>>>>>>>> do you know what commits should fix the issue?
>>>>>>>
>>>>>>> Look at the email on the stable mailing list:
>>>>>>> 	Subject: Re: Fix for 84676c1f (b5b6e8c8) missing in 4.14.y
>>>>>>> it should help you out here.
>>>>>>
>>>>>> Ah, I didn’t see that [1] yet. Also I can’t find the original message, and a
>>>>>> way to reply to that thread. Therefore, here is my reply.
>>>>>>
>>>>>>> Can you try the patches listed there?
>>>>>>
>>>>>> I tried some of these already without success.
>>>>>>
>>>>>> b5b6e8c8d3b4 scsi: virtio_scsi: fix IO hang caused by automatic irq vector affinity
>>>>>> 2f31115e940c scsi: core: introduce force_blk_mq
>>>>>> adbe552349f2 scsi: megaraid_sas: fix selection of reply queue
>>>>>>
>>>>>> The commit above is already in v4.14.56.
>>>>>>
>>>>>> 8b834bff1b73 scsi: hpsa: fix selection of reply queue
>>>>>>
>>>>>> The problem persists.
>>>>>>
>>>>>> The problem also persists with the state below.
>>>>>>
>>>>>> 3528f73a4e5d scsi: core: introduce force_blk_mq
>>>>>> 16dc4d8215f3 scsi: hpsa: fix selection of reply queue
>>>>>> f0a7ab12232d scsi: virtio_scsi: fix IO hang caused by automatic irq vector affinity
>>>>>> 6aba81b5a2f5 genirq/affinity: Don't return with empty affinity masks on error
>>>>>> 1aa1166eface (tag: v4.14.62, stable/linux-4.14.y) Linux 4.14.62
>>>>>>
>>>>>> So, some more commits are necessary.
>>>>>
>>>>> Or I revert the original patch here, and the follow-on ones that were
>>>>> added to "fix" this issue.  I think that might be the better thing
>>>>> overall here, right?  Have you tried that?
>>>>
>>>> Yes, reverting the commit fixed the issue for us. If Christoph or Ming do
>>>> not have another suggestion for a commit, that would be the way to go.
>>>
>>> Christoph or Ming, any ideas here?
>>>
>>> In looking at the aacraid code, I don't see anywhere that this is using
>>> a specific cpu number for queues or anything, but I could be wrong.
>>> Ideally this should also be failing in 4.17 or 4.18-rc right now as well
>>> as I don't see anything that would have "fixed" this recently.  Unless
>>> I'm missing something here?
>>
>> From both aac_fib_vector_assign() and aac_src_deliver_message(), looks
>> every msix vector is used inside driver, so causes this trouble.
>>
>> From 84676c1f21e8ff54b (genirq/affinity: assign vectors to all possible CPUs),
>> actually it should have been since 9a0ef98e18 (genirq/affinity: Assign vectors
>> to all present CPUs), it isn't guaranteed that one vector can be mapped to
>> at least one online CPU.
>>
>> So it should be fixed in driver by similar approach taken in the
>> following patches:
>> 	scsi: hpsa: fix selection of reply queue
>> 	scsi: megaraid_sas: fix selection of reply queue
>>
>> And the reason this issue won't be observed is that the following
>> patches(merged to v4.17) may avoid this issue, but in theory, the issue
>> won't be avoided completely by these patches:
>>
>> d3056812e7df genirq/affinity: Spread irq vectors among present CPUs as far as possible
>> 1a2d0914e23a genirq/affinity: Allow irq spreading from a given starting point
>> b3e6aaa8d94d genirq/affinity: Move actual irq vector spreading into a helper function
>> 47778f33dcba genirq/affinity: Rename *node_to_possible_cpumask as *node_to_cpumask
>> 0211e12dd0a5 genirq/affinity: Don't return with empty affinity masks on error
>>
>> In short, this issue should have been fixed in upstream aacraid, and the idea
>> is simple, use the current CPU id to retrieve the msix vector offset, this
>> way will make sure that the msix vector can be mapped from one online
>> CPU.
> 
> AACRAID folks, are you going to work on that? I looked at the code a bit,
> and it’ll take me some days to understand it and to fix it.

Unfortunately, there was no reply yet and I won’t be able to fix it any
time soon. The aacraid driver is still broken in 4.14.68. Reverting the
*one* mentioned commit fixes the issue.

Raghava, Dave, are you aware of the issue.

> Just out of curiosity, shouldn’t the subsystems(?) communicate better to
> avoid such breakage, or was that unexpected?


Kind regards,

Paul


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