On Fri, 25 Jan 2008, Robin Holt wrote: > > > > +void mmu_notifier_release(struct mm_struct *mm) > > > > +{ > > > > + struct mmu_notifier *mn; > > > > + struct hlist_node *n; > > > > + > > > > + if (unlikely(!hlist_empty(&mm->mmu_notifier.head))) { > > > > + rcu_read_lock(); > > > > + hlist_for_each_entry_rcu(mn, n, > > > > + &mm->mmu_notifier.head, > > > > hlist) { > > > > + if (mn->ops->release) > > > > + mn->ops->release(mn, mm); > > > > + hlist_del(&mn->hlist); > > > > > > I think the hlist_del needs to be before the function callout so we can > > > free > > > the structure without a use-after-free issue. > > > > The list head is in the mm_struct. This will be freed later. > > > > I meant the structure pointed to by &mn. I assume it is intended that > structure be kmalloc'd as part of a larger structure. The driver is the > entity which created that structure and should be the one to free it.
mn will be pointing to the listhead in the mm_struct one after the other. You mean the ops structure? > > > > +void mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct > > > > *mm) > > > > +{ > > > > + spin_lock(&mmu_notifier_list_lock); > > > > > > Shouldn't this really be protected by the down_write(mmap_sem)? Maybe: > > > > Ok. We could switch this to mmap_sem protection for the mm_struct but the > > rmap notifier is not associated with an mm_struct. So we would need to > > keep it there. Since we already have a spinlock: Just use it for both to > > avoid further complications. > > But now you are putting a global lock in where it is inappropriate. The lock is only used during register and unregister. Very low level usage. > > > XPMEM, would also benefit from a call early. We could make all the > > > segments as being torn down and start the recalls. We already have > > > this code in and working (have since it was first written 6 years ago). > > > In this case, all segments are torn down with a single message to each > > > of the importing partitions. In contrast, the teardown code which would > > > happen now would be one set of messages for each vma. > > > > So we need an additional global teardown call? Then we'd need to switch > > off the vma based invalidate_range()? > > No, EXACTLY what I originally was asking for, either move this call site > up, introduce an additional mmu_notifier op, or place this one in two > locations with a flag indicating which call is being made. Add a new invalidate_all() call? Then on exit we do 1. invalidate_all() 2. invalidate_range() for each vma 3. release() We cannot simply move the call up because there will be future range callbacks on vma invalidation. ------------------------------------------------------------------------- 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 kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel