I/O lockup

Gord R. Lamb (glamb@max-t.com)
Mon, 12 Nov 2001 13:01:23 -0500 (EST)


Hi everyone,

I've been having a problem for a while now with a strange lockup induced
under heavy SCSI I/O (particularly when I write directly to block devices
with dd of=/dev/sd?, but also when writing to a filesystem on that
device). I'm writing around 50-100mb/sec over FC (qlogic 2200) under
Linux 2.4 (tried 2.4.3 through 2.4.10).

It seems that some vm or I/O related spinlock is being taken and held, but
not released (?). There is no oops or BUG() or anything (no messages at
all in fact).. all I/O just stops. I can still invoke sysrq, type
characters at the console, etc. In fact, usually top continues to run and
display kswapd as the dominant process.

Any ideas?

- Gord R. Lamb (glamb@max-t.com)
Maximum Throughput, Inc.
Sr. Systems Architect

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