Re: [PATCH] replace the slots lock from the mmap_sem to private kvm lock

[Izik Eidus <izike@qumranet.com>]

Marcelo Tosatti wrote:
> On Mon, Feb 11, 2008 at 05:12:42PM +0200, Izik Eidus wrote:
>   
>> right now kvm take the down_read(mmap_sem) lock to make sure that no 
>> slots will be
>> removed while trying to get them / make the dirty log safe,
>> but in some cases when the down_read(mmap_sem) is called and after that 
>> kvm_read_guest() is called
>> copy_from_user can result in a page fault that will lead to recursivly 
>> taking the mmap_sem,
>>
>> this patch remove the mmap_sem, with new kvm private lock.
>>     
>
> Hi Izik,
>
> do_mmap/do_munmap requires the mmap_sem in write-mode.
>   

right, i missed it

> I couldnt find any sequence which grabs mmap_sem and then slots_lock,
> but it would be nice to verify again that can't happen.
>   

sure

> Other than that looks good.
>
>   

thanks

-- 
woof.


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