On 1/22/07, Neil Brown <neilb@xxxxxxx> wrote:
On Monday January 22, cebbert@xxxxxxxxxx wrote: > Justin Piszcz wrote: > > My .config is attached, please let me know if any other information is > > needed and please CC (lkml) as I am not on the list, thanks! > > > > Running Kernel 2.6.19.2 on a MD RAID5 volume. Copying files over Samba to > > the RAID5 running XFS. > > > > Any idea what happened here? .... > > > Without digging too deeply, I'd say you've hit the same bug Sami Farin > and others > have reported starting with 2.6.19: pages mapped with kmap_atomic() > become unmapped > during memcpy() or similar operations. Try disabling preempt -- that > seems to be the > common factor. That is exactly the conclusion I had just come to (a kmap_atomic page must be being unmapped during memcpy). I wasn't aware that others had reported it - thanks for that. Turning off CONFIG_PREEMPT certainly seems like a good idea.
Coming from an ARM background I am not yet versed in the inner workings of kmap_atomic, but if you have time for a question I am curious as to why spin_lock(&sh->lock) is not sufficient pre-emption protection for copy_data() in this case?
NeilBrown
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