Re: v5.4.289 failed to boot with error megasas_build_io_fusion 3219 sge_count (-12) is out of range

[Juergen Gross <jgross@suse.com>]

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On 29.01.25 10:15, Harshvardhan Jha wrote:
> 
> On 29/01/25 2:34 PM, Greg KH wrote:
>> On Wed, Jan 29, 2025 at 02:29:48PM +0530, Harshvardhan Jha wrote:
>>> Hi Greg,
>>>
>>> On 29/01/25 2:18 PM, Greg KH wrote:
>>>> On Wed, Jan 29, 2025 at 02:13:34PM +0530, Harshvardhan Jha wrote:
>>>>> Hi there,
>>>>>
>>>>> On 29/01/25 2:05 PM, Greg KH wrote:
>>>>>> On Wed, Jan 29, 2025 at 02:03:51PM +0530, Harshvardhan Jha wrote:
>>>>>>> Hi All,
>>>>>>>
>>>>>>> +stable
>>>>>>>
>>>>>>> There seems to be some formatting issues in my log output. I have
>>>>>>> attached it as a file.
>>>>>> Confused, what are you wanting us to do here in the stable tree?
>>>>>>
>>>>>> thanks,
>>>>>>
>>>>>> greg k-h
>>>>> Since, this is reproducible on 5.4.y I have added stable. The culprit
>>>>> commit which upon getting reverted fixes this issue is also present in
>>>>> 5.4.y stable.
>>>> What culprit commit?  I see no information here :(
>>>>
>>>> Remember, top-posting is evil...
>>> My apologies,
>>>
>>> The stable tag v5.4.289 seems to fail to boot with the following prompt in an infinite loop:
>>> [   24.427217] megaraid_sas 0000:65:00.0: megasas_build_io_fusion 3273 sge_count (-12) is out of range. Range is:  0-256
>>>
>>> Reverting the following patch seems to fix the issue:
>>>
>>> stable-5.4      : v5.4.285             - 5df29a445f3a xen/swiotlb: add
>>> alignment check for dma buffers
>>>
>>> I tried changing swiotlb grub command line arguments but that didn't
>>> seem to help much unfortunately and the error was seen again.
>>>
>> Ok, can you submit this revert with the information about why it should
>> not be included in the 5.4.y tree and cc: everyone involved and then we
>> will be glad to queue it up.
>>
>> thanks,
>>
>> greg k-h
> 
> This might be reproducible on other stable trees and mainline as well so
> we will get it fixed there and I will submit the necessary fix to stable
> when everything is sorted out on mainline.

Right. Just reverting my patch will trade one error with another one (the
one which triggered me to write the patch).

There are two possible ways to fix the issue:

- allow larger DMA buffers in xen/swiotlb (today 2MB are the max. supported
   size, the megaraid_sas driver seems to effectively request 4MB)

- fix the megaraid_sas driver by splitting up the allocated DMA buffer (it is
   requesting 2.3MB, which will be rounded up to 4MB - it is probably not needed
   to be in one chunk, so a split would result in max. 2MB chunk size)

Both variants have their pros and cons, though.


Juergen

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