[Linux-cachefs] 'bad page state' error

[David Howells]

Rob Bos <rbos at sfu.ca> wrote:

> I can reliably reproduce the error by mounting the filesystem with CIFS
> fscache enabled, then doing a cp on a file, and then hitting 'ctrl-c' to
> cancel the copy. This is on a separate VM with RHEL6.4 using the 373 kernel.
> 
> If I let the copy finish on its own, no error is generated; if I cancel the
> copy, it dumps 'bad page status' in dmesg.

Thanks!  That suggests a line of investigation that I might be able to
automate.

> Maybe aria2c generates these errors because torrents work in file chunks, so
> it opens, seeks, reads a chunk, and then closes. The kernel code may not
> handle partial reads properly, I speculate.

fscache can't tell the difference between a partial read and a full read.  You
would likely find that a full read is actually made up of several partial
reads.

On the other hand, it's possible that the partial page at the end is a
problem, I suppose.

Thanks again,
David