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

[Jürgen Groß]

On 30.01.25 06:27, Harshvardhan Jha wrote:
> On 30/01/25 3:31 AM, Stefano Stabellini wrote:
> > On Wed, 29 Jan 2025, Jürgen Groß wrote:
> > > On 29.01.25 19:35, Harshvardhan Jha wrote:
> > > > On 29/01/25 4:52 PM, Juergen Gross wrote:
> > > > > 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)
> > > > This seems relatively simpler to implement but I'm not sure whether it's
> > > > the most optimal approach
> > > Just making the static array larger used to hold the frame numbers for the
> > > buffer seems to be a waste of memory for most configurations.
> > >
> > > I'm thinking of an allocated array using the max needed size (replace a
> > > former buffer with a larger one if needed).
> > You are referring to discontig_frames and MAX_CONTIG_ORDER in
> > arch/x86/xen/mmu_pv.c, right? I am not super familiar with that code but
> > it looks like a good way to go.
>
> This rejected patch works on MAX_CONTIG_ORDER and doubles the buffer
> size but that is undesirable in most situations:
>
> https://lore.kernel.org/lkml/28947d4f-ab32-4a57-8dbb-e37fa4183a69@xxxxxxxx/t/
>
> What needs to be done is the buffer size will only be doubled when needed.

I'll write a patch.


Juergen

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