Re: [PATCH] livelock in elevator scheduling

[Russell Cattelan <cattelan@thebarn.com>]

Jens Axboe wrote:

> On Mon, Dec 04 2000, Russell Cattelan wrote:
> > I'm going to take a closer look at the scsi_back_merge_fn.
> > This may  have more to due with our/Chait's kiobuf modifications than
> > anything else.
> >
> >
> >
> > XFS (dev: 8/20) mounting with KIOBUFIO
> > Start mounting filesystem: sd(8,20)
> > Ending clean XFS mount for filesystem: sd(8,20)
> > kmem_alloc doing a vmalloc 262144 size & PAGE_SIZE 0 rval=0xe0a10000
> > Unable to handle kernel NULL pointer dereference at virtual address
> > 00000008
> >  printing eip:
> > c019f8b5
> > *pde = 00000000
> >
> > Entering kdb (current=0xc1910000, pid 5) on processor 1 Panic: Oops
> > due to panic @ 0xc019f8b5
> > eax = 0x00000002 ebx = 0x00000001 ecx = 0x00081478 edx = 0x00000000
> > esi = 0xc1957da0 edi = 0xc1923ac8 esp = 0xc1911e94 eip = 0xc019f8b5
> > ebp = 0xc1911e9c xss = 0x00000018 xcs = 0x00000010 eflags = 0x00010046
> > xds = 0x00000018 xes = 0x00000018 origeax = 0xffffffff &regs = 0xc1911e60
> > [1]kdb> bt
> >     EBP       EIP         Function(args)
> > 0xc1911e9c 0x00000000c019f8b5 scsi_back_merge_fn_c+0x15 (0xc1923a98,
> > 0xc1957da0, 0xcfb05780, 0x80)
> >                                kernel .text 0xc0100000 0xc019f8a0
>
> Ah, I see what it is now. The elevator is attempting to merge a buffer
> head into a kio based request, poof. The attached diff should take
> care of that in your tree.

Hmm..  Yup... that is actually the mods made for kio in our base XFS tree.
I wonder why the patch dropped them?
I should have caught that.

Thanks.
I'll let you know how things go.


>
>
> --
> * Jens Axboe <axboe@suse.de>
> * SuSE Labs
>
>   ------------------------------------------------------------------------
>
>    xfs-elv-1Name: xfs-elv-1
>             Type: Plain Text (text/plain)

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