From: "Paul E. McKenney" <paulmck@kernel.org>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: "Zhang, Qiang" <qiang.zhang@windriver.com>,
Josh Triplett <josh@joshtriplett.org>,
Steven Rostedt <rostedt@goodmis.org>,
Joel Fernandes <joel@joelfernandes.org>,
rcu@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
kasan-dev <kasan-dev@googlegroups.com>,
Uladzislau Rezki <urezki@gmail.com>
Subject: Re: [PATCH] rcu: kasan: record and print kvfree_call_rcu call stack
Date: Fri, 20 Nov 2020 06:45:50 -0800 [thread overview]
Message-ID: <20201120144550.GA8216@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <20201120143440.GF1437@paulmck-ThinkPad-P72>
On Fri, Nov 20, 2020 at 06:34:40AM -0800, Paul E. McKenney wrote:
> On Fri, Nov 20, 2020 at 09:51:15AM +0100, Dmitry Vyukov wrote:
> > On Thu, Nov 19, 2020 at 10:49 PM Paul E. McKenney <paulmck@kernel.org> wrote:
> > >
> > > On Wed, Nov 18, 2020 at 11:53:09AM +0800, qiang.zhang@windriver.com wrote:
> > > > From: Zqiang <qiang.zhang@windriver.com>
> > > >
> > > > Add kasan_record_aux_stack function for kvfree_call_rcu function to
> > > > record call stacks.
> > > >
> > > > Signed-off-by: Zqiang <qiang.zhang@windriver.com>
> > >
> > > Thank you, but this does not apply on the "dev" branch of the -rcu tree.
> > > See file:///home/git/kernel.org/rcutodo.html for more info.
> > >
> > > Adding others on CC who might have feedback on the general approach.
> > >
> > > Thanx, Paul
> > >
> > > > ---
> > > > kernel/rcu/tree.c | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > > > index da3414522285..a252b2f0208d 100644
> > > > --- a/kernel/rcu/tree.c
> > > > +++ b/kernel/rcu/tree.c
> > > > @@ -3506,7 +3506,7 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> > > > success = true;
> > > > goto unlock_return;
> > > > }
> > > > -
> > > > + kasan_record_aux_stack(ptr);
> > > > success = kvfree_call_rcu_add_ptr_to_bulk(krcp, ptr);
> > > > if (!success) {
> > > > run_page_cache_worker(krcp);
> >
> > kvfree_call_rcu is intended to free objects, right? If so this is:
>
> True, but mightn't there still be RCU readers referencing this object for
> some time, as in up to the point that the RCU grace period ends? If so,
> won't adding this cause KASAN to incorrectly complain about those readers?
>
> Or am I missing something here?
For example, is kasan_record_aux_stack() -only- recording the stack and
not at all updating the allocated/freed state?
Thanx, Paul
> > Acked-by: Dmitry Vyukov <dvyukov@google.com>
next prev parent reply other threads:[~2020-11-20 14:46 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 3:53 [PATCH] rcu: kasan: record and print kvfree_call_rcu call stack qiang.zhang
2020-11-19 21:49 ` Paul E. McKenney
2020-11-20 8:51 ` Dmitry Vyukov
2020-11-20 14:34 ` Paul E. McKenney
2020-11-20 14:44 ` Dmitry Vyukov
2020-11-20 14:54 ` Paul E. McKenney
2020-11-20 14:45 ` Paul E. McKenney [this message]
2020-11-20 11:59 ` Uladzislau Rezki
2020-11-20 12:06 ` Dmitry Vyukov
2020-11-20 12:49 ` Uladzislau Rezki
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