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

[Rik van Riel <riel@redhat.com>]

On 04/08/2010 10:11 AM, Linus Torvalds wrote:
>
>
> On Thu, 8 Apr 2010, Borislav Petkov wrote:
>>
>> There are still issues: vma_adjust() grabs mapping->i_mmap_lock for file
>> mappings while we might sleep in anon_vma_prepare():
>
> Ahh. Good catch. So I can't actually do that anon_vma_prepare() thing in
> __insert_vm_struct.
>
> It should be simple enough to just move it into the caller, just after it
> releases that lock. There's only one user of that __insert_vm_struct()
> anyway. You can do it yourself, or you can replace my previous patch with
> this..
>
> [ The patch below also makes it warn once and return SIGBUS for the case
>    where there is no anon_vma.  I decided I still want to hear about it if
>    there might be some path that tries to insert a vma on its own ]

Reviewed-by: Rik van Riel <riel@redhat.com>

I haven't seen any places that insert VMAs by itself.
Several strange places that allocate them, but they
all appear to use the standard functions to insert them.