Re: [uml-devel] usermode linux hoses 2.2.18-SMP host machine when run

[Jeff Dike]

[e-mail] said:
> When run from a normal user account with its current working directory
> on a NFS filesystem, usermode linux causes the host machine's kernel
> to enter a hosed state. No processes (including UML) seem to respond,
> and the machine becomes unusable. 

Just to clarify what I think UML is doing that's causing the trouble: it is an 
extensive user of mmap.  It creates several files (one 16 meg by default, but 
possibly much larger) in $PWD, and mmaps them into all of its threads.  The 
"physical memory" file also has individual pages mapped twice (or more) into 
various threads.

I've seen this confuse an old version of reiserfs and NFS, although not so 
much that the machine hung.  UML would just see stale data, get horribly 
confused by it, and crash.

				Jeff