r358252 causes intermittent hangs where processes are stuck sleeping on btalloc

Hi,

Since I hadn't upgraded a kernel through the winter, it took me a while
to bisect this, but r358252 seems to be the culprit.

If I do a kernel build over NFS using my not so big Pentium 4 (single core,
1.25Gbytes RAM, i386), about every second attempt will hang.
When I do a "ps" in the debugger, I see processes sleeping on btalloc.
If I revert to r358251, I cannot reproduce this.

Any ideas?

I can easily test any change you might suggest to see if it fixes the
problem.

If you want more debug info, let me know, since I can easily
reproduce it.

Thanks, rick