Re: [RESEND PATCH 1/3] uprobes: Remove redundant lock_page/unlock_page

[Ingo Molnar <mingo@kernel.org>]

* Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote:

> From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> 
> Since read_opcode() reads from the referenced page and doesnt modify
> the page contents nor the page attributes, there is no need to lock
> the page.
> 
> Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> ---
>  Modified changelog based on comments from Peter Zijlstra
> 
>  kernel/events/uprobes.c |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 42b21eb..b3f3095 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -315,12 +315,10 @@ static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_
>  	if (ret <= 0)
>  		return ret;
>  
> -	lock_page(page);
>  	vaddr_new = kmap_atomic(page);
>  	vaddr &= ~PAGE_MASK;
>  	memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE);
>  	kunmap_atomic(vaddr_new);
> -	unlock_page(page);
>  
>  	put_page(page);

Is this also a bug fix, or can it wait until v3.6?

Thanks,

	Ingo