Re: [PATCH -rcu v2] kcsan: Make KCSAN compatible with lockdep

[Marco Elver]

On Thu, 16 Jan 2020 at 18:43, Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
>
> On Wed, Jan 15, 2020 at 05:25:12PM +0100, Marco Elver wrote:
> > We must avoid any recursion into lockdep if KCSAN is enabled on
> > utilities used by lockdep. One manifestation of this is corrupting
> > lockdep's IRQ trace state (if TRACE_IRQFLAGS). Fix this by:
> >
> > 1. Using raw_local_irq{save,restore} in kcsan_setup_watchpoint().
> > 2. Disabling lockdep in kcsan_report().
> >
> > Tested with:
> >
> >   CONFIG_LOCKDEP=y
> >   CONFIG_DEBUG_LOCKDEP=y
> >   CONFIG_TRACE_IRQFLAGS=y
> >
> > Where previously, the following warning (and variants with different
> > stack traces) was consistently generated, with the fix introduced in
> > this patch, the warning cannot be reproduced.

Qian, thank you for testing!

> I added Vlad's ack and Qian's Tested-by and queued this.  Thank you all!

Thank you, Paul!

-- Marco