Re: Processes stuck in unkillable D state (now seen in 2.6.7-mm6)

["Rob Mueller" <robm@fastmail.fm>]

> Ugh, so the call path here is:
>
> reiserfs_file_write -> start a transaction
> copy_from_user -> fault in the page
> page fault handler -> lock page
>
> This means we're trying to lock a page with a running transaction, and
> that's not allowed, since some other process on the box most likely has
> that page locked and is trying to start a transaction.
>
> That makes for 3 different deadlocks in this exact same call path
> (dirty_inode, lock_page and kmap), and my patch for it has major
> problems.  So, I'll talk things over with everyone during OLS and try to
> work out a proper fix.
>
> Sorry Rob, this one is non-trivial.

Thanks for looking at it Chris. At least it seems that there is now a 
diagnosis of what's happening, which can be half the battle!

I'm surprised that this seems so rare, and that no-one else has reported it 
as a significant problem before. Do you think there's anything in particular 
about our kernel config that would be causing this to happen?

Rob