linux-kernel - Re: [PATCH tip/x86/asm] uprobes: __create_xol_area() must nullify xol

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Message-ID: <20160229161457.GM6344@twins.programming.kicks-ass.net>
Date:	Mon, 29 Feb 2016 17:14:57 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andy Lutomirski <tipbot@...or.com>, Ingo Molnar <mingo@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>,
	Pratyush Anand <panand@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH tip/x86/asm] uprobes: __create_xol_area() must nullify
 xol_mapping.fault

On Mon, Feb 29, 2016 at 04:51:14PM +0100, Oleg Nesterov wrote:
> On 02/29, Peter Zijlstra wrote:
> >
> > On Sat, Feb 27, 2016 at 11:11:28PM +0100, Oleg Nesterov wrote:
> > > --- a/kernel/events/uprobes.c
> > > +++ b/kernel/events/uprobes.c
> > > @@ -1178,6 +1178,7 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
> > >  		goto free_area;
> > >
> > >  	area->xol_mapping.name = "[uprobes]";
> > > +	area->xol_mapping.fault = NULL;
> > >  	area->xol_mapping.pages = area->pages;
> >
> > Would not something like:
> >
> > 	area->xol_mapping = (struct vm_special_mapping){
> > 		.name = "[uprobes]",
> > 		.pages = area->pages,
> > 	};
> >
> > Be a more robust approach? That way, if someone adds more fields, they
> > at least get initialized (to 0).
> 
> OK, agreed...
> 
> Do you want me to send v2? Or incremental patch because this one is already in
> -tip tree.
> 
> Or do nothing unless you feel strongly about it. area->xol_mapping should go away,
> but we need a simple preparation in mm/mmap.c.

Yeah, no real strong feelings. Esp. if you're working on getting it
killed.