linux-kernel - Re: [RFC V3] mm: Generalize and rename notify_page_fault() as kprobe_page

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Message-ID: <bc8e2140-dc78-ce99-a336-91733c2fda67@arm.com>
Date:   Mon, 10 Jun 2019 10:06:34 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     Dave Hansen <dave.hansen@...el.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        x86@...nel.org, Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Matthew Wilcox <willy@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Christophe Leroy <christophe.leroy@....fr>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Tony Luck <tony.luck@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        "David S. Miller" <davem@...emloft.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [RFC V3] mm: Generalize and rename notify_page_fault() as
 kprobe_page_fault()



On 06/07/2019 08:36 PM, Dave Hansen wrote:
> On 6/7/19 3:34 AM, Anshuman Khandual wrote:
>> +static nokprobe_inline bool kprobe_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;
>> +}
> 
> Nits: Other that taking the nice, readable, x86 one and globbing it onto
> a single line, looks OK to me.  It does seem a _bit_ silly to go to the
> trouble of converting to 'bool' and then using 0/1 and an 'int'
> internally instead of true/false and a bool, though.  It's also not a

Changing to 'bool'...

> horrible thing to add a single line comment to this sucker to say:
> 
> /* returns true if kprobes handled the fault */
> 

Picking this in-code comment.

> In any case, and even if you don't clean any of this up:
> 
> Reviewed-by: Dave Hansen <dave.hansen@...ux.intel.com>
> 

Thanks !