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 <20201119214934.GC1437@paulmck-ThinkPad-P72> <20201120115935.GA8042@pc636>
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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Fri, 20 Nov 2020 13:06:39 +0100
Message-ID: <CACT4Y+bHpju_vXjdtb46O=zbQKTFaCSuoTKu1ggZ=CZ9SqWhXQ@mail.gmail.com>
Subject: Re: [PATCH] rcu: kasan: record and print kvfree_call_rcu call stack
To:     Uladzislau Rezki <urezki@gmail.com>
Cc:     Zqiang <qiang.zhang@windriver.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        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>
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On Fri, Nov 20, 2020 at 12:59 PM Uladzislau Rezki <urezki@gmail.com> wrote:
>
> On Thu, Nov 19, 2020 at 01:49:34PM -0800, Paul E. McKenney 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);
> Is that save to invoke it on vmalloced ptr.?

Yes, kasan_record_aux_stack should figure it out itself.
We call kasan_record_aux_stack on call_rcu as well, and rcu structs
can be anywhere.
See:
https://elixir.bootlin.com/linux/v5.10-rc4/source/mm/kasan/generic.c#L335