Messages in this thread | | | Date | Mon, 14 Jan 2008 12:02:42 -0800 (PST) | From | Christoph Lameter <> | Subject | Re: [PATCH] mmu notifiers #v2 |
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On Sun, 13 Jan 2008, Andrea Arcangeli wrote:
> About the locking perhaps I'm underestimating it, but by following the > TLB flushing analogy, by simply clearing the shadow ptes (with kvm > mmu_lock spinlock to avoid racing with other vcpu spte accesses of > course) and flushing the shadow-pte after clearing the main linux pte, > it should be enough to serialize against shadow-pte page faults that > would call into get_user_pages. Flushing the host TLB before or after > the shadow-ptes shouldn't matter.
Hmmm... In most of the callsites we hold a writelock on mmap_sem right?
> Comments welcome... especially from SGI/IBM/Quadrics and all other > potential users of this functionality.
> There are also certain details I'm uncertain about, like passing 'mm' > to the lowlevel methods, my KVM usage of the invalidate_page() > notifier for example only uses 'mm' for a BUG_ON for example:
Passing mm is fine as long as mmap_sem is held.
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h > --- a/include/asm-generic/pgtable.h > +++ b/include/asm-generic/pgtable.h > @@ -86,6 +86,7 @@ do { \ > pte_t __pte; \ > __pte = ptep_get_and_clear((__vma)->vm_mm, __address, __ptep); \ > flush_tlb_page(__vma, __address); \ > + mmu_notifier(invalidate_page, (__vma)->vm_mm, __address); \ > __pte; \ > }) > #endif
Hmmm... this is ptep_clear_flush? What about the other uses of flush_tlb_page in asm-generic/pgtable.h and related uses in arch code? (would help if your patches would mention the function name in the diff headers)
> +#define mmu_notifier(function, mm, args...) \ > + do { \ > + struct mmu_notifier *__mn; \ > + struct hlist_node *__n; \ > + \ > + hlist_for_each_entry(__mn, __n, &(mm)->mmu_notifier, hlist) \ > + if (__mn->ops->function) \ > + __mn->ops->function(__mn, mm, args); \ > + } while (0)
Does this have to be inline? ptep_clear_flush will become quite big
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