Re: 2.6 must-fix list, v2

[Andrew Morton]

Trond Myklebust <[e-mail]> wrote:
>
> The dirty pages are failing to be written out because
> they've been swapped out. We then try to do an RPC call to the server
> to get it to truncate the file on its side.
> Meanwhile one or more of the swapped out pages are faulted in, and
> attempted written out. -> race...

These are file-backed pages: they don't get swapped out.  The VM will write
them out with ->writepage(), and will reclaim them when they are clean.

A filemap_fdatawait() will do the right thing with these pages: it'll wait
on them.

There is a weird race in there wrt ongoing pagefaults in the truncated
region, but they require two processes - one faulting, the other
truncating.  fsx-linux doesn't do that.

I'd need to see some more details on the code flow, including pointers to
the relevant code in the NFS client to understand this one please.