Locked up processes after upgrade to ZFS v15

[Andriy Gapon]

on 12/10/2010 13:07 Jeremy Chadwick said the following:
> I've been trying to reproduce this problem on my testbed box without
> much luck so far.  The box differs severely -- the biggest differences
> being the testbed runs i386 (due to CPU), only has 1GB RAM, and is
> single-core.  I don't have an amd64 testbed system on hand right now.
> 
> I've been trying to reproduce it by enabling Sendfile and MMAP in Apache
> on the system, putting up some very large files on an Apache-accessible
> ZFS filesystem, and using something like "wget -r" to download
> everything.  I've been watching "netstat -m" to monitor the number of
> sendfile requests.
> 
> There have been a couple cases where I've seen processes go into "zfs"
> state, but I have yet to see any lock up.
> 
> Is there something amd64-specific to the problem at hand, or maybe some
> VM feature which isn't getting triggered on i386?  Or do you know of a
> reliable way to reproduce the issue at this point?

I don't have an easy way to reproduce it.
The theory is that you should sendfile a file with size which is not multiple of
page size (4K) and then you should mmap and read the same file; the last step
should lock up.
Perhaps, tools/regression/sockets/sendfile/sendfile.c with the following patch
would reproduce it?
http://people.freebsd.org/~avg/sendfile.diff
-- 
Andriy Gapon