From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matthew Wilcox <willy@infradead.org>
Date: Tue, 04 Jun 2019 21:53:26 +0000
Subject: Re: [RFC V2] mm: Generalize notify_page_fault()
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To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>, Michal Hocko <mhocko@suse.com>, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>, Catalin Marinas <catalin.marinas@arm.com>, Dave Hansen <dave.hansen@linux.intel.com>, Will Deacon <will.deacon@arm.com>, linux-mm@kvack.org, Paul Mackerras <paulus@samba.org>, sparclinux@vger.kernel.org, linux-s390@vger.kernel.org, Yoshinori Sato <ysato@users.sourceforge.jp>, Michael Ellerman <mpe@ellerman.id.au>, x86@kernel.org, Russell King <linux@armlinux.org.uk>, Ingo Molnar <mingo@redhat.com>, Fenghua Yu <fenghua.yu@intel.com>, Stephen Rothwell <sfr@canb.auug.org.au>, Andrey Konovalov <andreyknvl@google.com>, Andy Lutomirski <luto@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, linux-arm-kernel@lists.infradead.org, Christophe Leroy <christophe.leroy@c-s.fr>, Tony Luck <tony.luck@intel.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, linux-kernel@vger.kernel.org, Martin Schwidefsky <schwidefsky@de.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, linuxppc-dev@lists.ozlabs.org, "David S. Miller" <davem@davemloft.net>

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.