crash below shrink_dcache_memory

[Roland Kuhn]

Hi!

We're having trouble here with our data acquisition systems when  
recording some 10MB/s from a PCI card to a file on NFS, using write 
()'s of about 8kB. I thought is was connected to running X at the  
same time, but without X it also happened and I got part of a backtrace:

[scrolled off]
kdb
die
vprintk
do_page_fault
do_page_fault
iput
load_balance_newidle
schedule
do_page_fault
error_code
nfs_dentry_iput
iput
nfs_dentry_iput
prune_dcache
shrink_dcache_memory
shrink_slab
balance_pgdat
prepare_to_wait
kswapd
[...]

The system is Scientific Linux CERN 4.3, based on RHEL4, kernel  
2.6.9-34.EL.cernsmp, running on a two-way Xeon. What I'd like to know  
is whether a page fault can legally happen while shrinking the  
dcache; this sounds a bit counterintuitive to me. If anyone has an  
idea where to look for the cause of the crash, you're welcome.

Ciao,
                    Roland

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