Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmasof a mergeable VMA

[Linus Torvalds]

On Thu, 8 Apr 2010, Borislav Petkov wrote:
> 
> And this happens quite often - I changed the WARN_ONCE to WARN and can't
> start kvm, iceowl (mozilla calendar) and the console-kit-daemon craps up
> upon boot too:

Hmm. I tried console-kit-daemon, which I had installed, but didn't get 
anything like that. Probably some setup difference.

I also went through every user of 'vm_area_cachep', and saw nothing 
suspicious at least for the mmu case (I didn't check the nommu.c code). I 
must have missed something.

One thing you could do is to add some more debugging info when that "no 
anon_vma" warning happens. In particular, if you still have the SLUB 
debugging on, you could try to do that

	page = virt_to_head_page(vma);
	object_err(vm_area_cachep, page, (void *)vma, "NULL anon_vma");

and it should give you _which_ routine did the kmem_cache_alloc() for the 
vma that doesn't have an anon_vma.

		Linus
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