Re: sendfile() broken with 2.6.26 + Apache 2 ?

From: J. K. Cliburn
Date: Sat Jul 19 2008 - 08:32:18 EST

Ian Jeffray wrote:

I moved from kernel to 2.6.26 yesterday and observed that
large files sent via Apache2 are partially corrupt.

This appears to be linked to sendfile() -- disabling the use of
sendfile in the apache config (EnableSendfile Off) allows it to
function as normal.

My system is a simple Core2Duo running Debian lenny/sid; nothing
special, and I have never observed problems like this before.

The problem feels certainly related to sendfile() since the data
reads correctly from disc in other programs, and via CIFS etc.

The corruption happens part-way in to the file... I've no exact
figure but it would seem like maybe 32KB -- I'm seeing broken
PNGs served from Apache, where the top few dozen lines decode
correctly, and the rest is garbage.

I've made basically no configuration changes between and
2.6.26 and have explicitly tried both enabling and disabling the
new PAT support to no effect.

This is completely repeatable and reproducible.

Is anyone else seeing this broken behaviour?

Can you please enable verbose logging

echo 8 > /proc/sys/kernel/printk
ethtool -s eth0 msglvl 0xffff

and see if the driver issues any error messages as the file is transferred?
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