Andrea Arcangeli wrote: > On Tue, Jan 22, 2008 at 03:41:02PM +0200, Avi Kivity wrote: > >> Andrea Arcangeli wrote: >> >>> I still can't see how it could be possibly make a difference for the >>> mm_count if the kvm module is compiled inside the kernel or as an >>> external module, the reference counting there hasn't changed since >>> ages. The mmdrop fires only in the first overflow so even if I'm right >>> it probably wasn't much destabilizing to go negative given it happened >>> at mm destruction time. >>> >>> >>> >> It's this bit: >> > > Ok. But the atomic_inc removal isn't conditional to < 2.6.25, so it > still doesn't look good to me.
Right. Not hurting in practice since 2.6.25 has yet to be released, but it needs fixing. > it would look better if we would > unconditionally define mmdrop to nop in the external module > compile. The other problem is that I don't see why atomic_inc/mmdrop > are needed at all if the external module is safe, so why don't we drop > them? In ->release->kvm_destroy_vm it seems the kvm->mm is never used > anyway. > The external module isn't safe, it just works in practice. The meaning of hvas and ->mmap_sem (and mmu notifiers) is dependent on ->mm, so we must be sure that kvm doesn't get called with the wrong mm. Switching to a syscall based API would also cure this, but it's a lot more work. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kvm-devel
