From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH 3/4] KVM: Count the number of dirty pages for dirty
 logging
Date: Fri, 23 Dec 2011 09:14:51 -0200
Message-ID: <20111223111451.GD24308@amt.cnet>
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Cc: Avi Kivity <avi@redhat.com>, kvm@vger.kernel.org,
	takuya.yoshikawa@gmail.com
To: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
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On Tue, Dec 20, 2011 at 01:29:35PM +0900, Takuya Yoshikawa wrote:
> (2011/11/14 19:07), Avi Kivity wrote:
> >>@@ -1491,7 +1492,8 @@ void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot,
> >>  	if (memslot&&  memslot->dirty_bitmap) {
> >>  		unsigned long rel_gfn = gfn - memslot->base_gfn;
> >>
> >>-		__set_bit_le(rel_gfn, memslot->dirty_bitmap);
> >>+		if (!__test_and_set_bit_le(rel_gfn, memslot->dirty_bitmap))
> >>+			memslot->nr_dirty_pages++;
> >>  	}
> >>  }
> >>
> 
> [snip]
> 
> >btw mark_page_dirty() itself seems to assume mmu_lock protection that
> >doesn't exist.  Marcelo?
> >

Not mmu_lock protection, kvm->srcu protection.

> I want to hear the answer for this question.
> 
> Though I myself is reading the code, I cannot understand it thoroughly yet.
> I wish if there were mmu_lock entry in locking.txt ...

Agreed.