[RFC V2] mm: Generalize notify_page_fault()

[Matthew Wilcox]

On Tue, Jun 04, 2019 at 12:04:06PM +0530, Anshuman Khandual wrote:
> +++ b/arch/x86/mm/fault.c
> @@ -46,23 +46,6 @@ kmmio_fault(struct pt_regs *regs, unsigned long addr)
>  	return 0;
>  }
>  
> -static nokprobe_inline int kprobes_fault(struct pt_regs *regs)
> -{
...
> -}

> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e8834a..c5a8dcf 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1778,6 +1778,7 @@ static inline int pte_devmap(pte_t pte)
>  }
>  #endif
>  
> +int notify_page_fault(struct pt_regs *regs, unsigned int trap);

Why is it now out-of-line?  

> +++ b/mm/memory.c
> +int __kprobes notify_page_fault(struct pt_regs *regs, unsigned int trap)
> +{
> +	int ret = 0;
> +
> +	/*
> +	 * To be potentially processing a kprobe fault and to be allowed
> +	 * to call kprobe_running(), we have to be non-preemptible.
> +	 */
> +	if (kprobes_built_in() && !preemptible() && !user_mode(regs)) {
> +		if (kprobe_running() && kprobe_fault_handler(regs, trap))
> +			ret = 1;
> +	}
> +	return ret;
> +}
> +

I would argue this should be in kprobes.h as a static nokprobe_inline.