This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
Re: [PATCH v2 2.6.38-rc8-tip 7/20] 7: uprobes: store/restore original instruction.
- From: Peter Zijlstra <peterz at infradead dot org>
- To: balbir at linux dot vnet dot ibm dot com
- Cc: Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Stephen Wilson <wilsons at start dot ca>, Ingo Molnar <mingo at elte dot hu>, Steven Rostedt <rostedt at goodmis dot org>, Linux-mm <linux-mm at kvack dot org>, Arnaldo Carvalho de Melo <acme at infradead dot org>, Linus Torvalds <torvalds at linux-foundation dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Christoph Hellwig <hch at infradead dot org>, Andi Kleen <andi at firstfloor dot org>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, Oleg Nesterov <oleg at redhat dot com>, LKML <linux-kernel at vger dot kernel dot org>, Jim Keniston <jkenisto at linux dot vnet dot ibm dot com>, Roland McGrath <roland at hack dot frob dot com>, SystemTap <systemtap at sources dot redhat dot com>, Andrew Morton <akpm at linux-foundation dot org>, "Paul E. McKenney" <paulmck at linux dot vnet dot ibm dot com>
- Date: Tue, 15 Mar 2011 20:30:32 +0100
- Subject: Re: [PATCH v2 2.6.38-rc8-tip 7/20] 7: uprobes: store/restore original instruction.
- References: <20110314133403.27435.7901.sendpatchset@localhost6.localdomain6> <20110314133522.27435.45121.sendpatchset@localhost6.localdomain6> <20110314180914.GA18855@fibrous.localdomain> <20110315092247.GW24254@linux.vnet.ibm.com> <1300211862.2203.302.camel@twins> <20110315185841.GH3410@balbir.in.ibm.com>
On Wed, 2011-03-16 at 00:28 +0530, Balbir Singh wrote:
>
> mm->owner should be under rcu_read_lock, unless the task is exiting
> and mm_count is 1. mm->owner is updated under task_lock().
>
> > Also, the assignments in kernel/fork.c and kernel/exit.c don't use
> > rcu_assign_pointer() and therefore lack the needed write barrier.
> >
>
> Those are paths when the only context using the mm->owner is single
>
> > Git blames Balbir for this.
>
> I accept the blame and am willing to fix anything incorrect found in
> the code.
:-), ok sounds right, just wasn't entirely obvious when having a quick
look.