2006-03-09 12:07:51

by Justin Piszcz

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Subject: Linux SCSI Error Question with SG Driver

I have a tape library connected to a Linux box here and every once and a
while I see these in dmesg:

sg_low_free: bad mem_src=0, buff=0xdb6a8000, rqSz=32768
sg_low_free: bad mem_src=0, buff=0xdb6b0000, rqSz=28672
sg_low_free: bad mem_src=0, buff=0xdb738000, rqSz=32768
sg_low_free: bad mem_src=0, buff=0xdb718000, rqSz=28672
sg_low_free: bad mem_src=0, buff=0xdb680000, rqSz=32768
sg_low_free: bad mem_src=0, buff=0xdb678000, rqSz=28672
sg_low_free: bad mem_src=0, buff=0xdb670000, rqSz=32768
sg_low_free: bad mem_src=0, buff=0xdb668000, rqSz=28672
sg_low_free: bad mem_src=0, buff=0xdb660000, rqSz=32768
sg_low_free: bad mem_src=0, buff=0xdb658000, rqSz=28672
sg_low_free: bad mem_src=0, buff=0xdb650000, rqSz=32768
sg_low_free: bad mem_src=0, buff=0xdb648000, rqSz=28672

Does anyone know what they refer to?

A quick google and newsgroup search just turn out the actual snippets of
code that produce these errors, thanks..

Justin.


2006-03-09 14:25:22

by Douglas Gilbert

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Subject: Re: Linux SCSI Error Question with SG Driver

Justin Piszcz wrote:
> I have a tape library connected to a Linux box here and every once and a
> while I see these in dmesg:
>
> sg_low_free: bad mem_src=0, buff=0xdb6a8000, rqSz=32768
> sg_low_free: bad mem_src=0, buff=0xdb6b0000, rqSz=28672
> sg_low_free: bad mem_src=0, buff=0xdb738000, rqSz=32768
> sg_low_free: bad mem_src=0, buff=0xdb718000, rqSz=28672
> sg_low_free: bad mem_src=0, buff=0xdb680000, rqSz=32768
> sg_low_free: bad mem_src=0, buff=0xdb678000, rqSz=28672
> sg_low_free: bad mem_src=0, buff=0xdb670000, rqSz=32768
> sg_low_free: bad mem_src=0, buff=0xdb668000, rqSz=28672
> sg_low_free: bad mem_src=0, buff=0xdb660000, rqSz=32768
> sg_low_free: bad mem_src=0, buff=0xdb658000, rqSz=28672
> sg_low_free: bad mem_src=0, buff=0xdb650000, rqSz=32768
> sg_low_free: bad mem_src=0, buff=0xdb648000, rqSz=28672
>
> Does anyone know what they refer to?

Justin,
That looks like the sg driver in the lk 2.4 series.
When it comes to free up some memory in sg_low_free()
it checks where the memory was sourced from. A
mem_src of 0 is not defined hence the error message.

Hard to say why this happens as the buff addresses
and rqSz values look reasonable.

Doug Gilbert