On Fri, May 27, 2022 at 08:24:03AM -0700, Paul E. McKenney wrote:
> On Fri, May 27, 2022 at 05:13:18PM +0200, Dmitry Vyukov wrote:
> > On Fri, 27 May 2022 at 17:07, Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote:
> > >
> > > From: Johannes Berg <johannes.berg@xxxxxxxxx>
> > >
> > > When running KASAN with Tiny RCU (e.g. under ARCH=um, where
> > > a working KASAN patch is now available), we don't get any
> > > information on the original kfree_rcu() (or similar) caller
> > > when a problem is reported, as Tiny RCU doesn't record this.
> > >
> > > Add the recording, which required pulling kvfree_call_rcu()
> > > out of line for the KASAN case since the recording function
> > > (kasan_record_aux_stack_noalloc) is neither exported, nor
> > > can we include kasan.h into rcutiny.h.
> > >
> > > without KASAN, the patch has no size impact (ARCH=um kernel):
> > > text data bss dec hex filename
> > > 6151515 4423154 33148520 43723189 29b29b5 linux
> > > 6151515 4423154 33148520 43723189 29b29b5 linux + patch
> > >
> > > with KASAN, the impact on my build was minimal:
> > > text data bss dec hex filename
> > > 13915539 7388050 33282304 54585893 340ea25 linux
> > > 13911266 7392114 33282304 54585684 340e954 linux + patch
> > > -4273 +4064 +-0 -209
> > >
> > > Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
> >
> > >From KASAN perspective:
> >
> > Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> >
> > What tree should it go into? mm? rcu? +Paul
>
> If Johannes is johill on IRC, I already agreed to take it. If not,
> we might have dueling patches.
>
> Ah, "Berg" -> "Hill". I never would have figured that out without
> this hint. ;-)
And applied with Dmitry's ack. It will show up on -rcu after my next
rebase.
Thanx, Paul
> > > ---
> > > include/linux/rcutiny.h | 11 ++++++++++-
> > > kernel/rcu/tiny.c | 14 ++++++++++++++
> > > 2 files changed, 24 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
> > > index 5fed476f977f..d84e13f2c384 100644
> > > --- a/include/linux/rcutiny.h
> > > +++ b/include/linux/rcutiny.h
> > > @@ -38,7 +38,7 @@ static inline void synchronize_rcu_expedited(void)
> > > */
> > > extern void kvfree(const void *addr);
> > >
> > > -static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> > > +static inline void __kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> > > {
> > > if (head) {
> > > call_rcu(head, func);
> > > @@ -51,6 +51,15 @@ static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> > > kvfree((void *) func);
> > > }
> > >
> > > +#ifdef CONFIG_KASAN_GENERIC
> > > +void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
> > > +#else
> > > +static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> > > +{
> > > + __kvfree_call_rcu(head, func);
> > > +}
> > > +#endif
> > > +
> > > void rcu_qs(void);
> > >
> > > static inline void rcu_softirq_qs(void)
> > > diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
> > > index 340b3f8b090d..58ff3721d975 100644
> > > --- a/kernel/rcu/tiny.c
> > > +++ b/kernel/rcu/tiny.c
> > > @@ -217,6 +217,20 @@ bool poll_state_synchronize_rcu(unsigned long oldstate)
> > > }
> > > EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu);
> > >
> > > +#ifdef CONFIG_KASAN_GENERIC
> > > +void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
> > > +{
> > > + if (head) {
> > > + void *ptr = (void *) head - (unsigned long) func;
> > > +
> > > + kasan_record_aux_stack_noalloc(ptr);
> > > + }
> > > +
> > > + __kvfree_call_rcu(head, func);
> > > +}
> > > +EXPORT_SYMBOL_GPL(kvfree_call_rcu);
> > > +#endif
> > > +
> > > void __init rcu_init(void)
> > > {
> > > open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
> > > --
> > > 2.36.1
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@xxxxxxxxxxxxxxxx.
> > > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20220527170743.04c21d235467.I1f79da0f90fb9b557ec34932136c656bc64b8fbf%40changeid.
