Messages in this thread | | | From | Dmitry Vyukov <> | Date | Fri, 27 May 2022 17:46:11 +0200 | Subject | Re: [RFC PATCH v3] UML: add support for KASAN under x86_64 |
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On Fri, 27 May 2022 at 16:28, Johannes Berg <johannes@sipsolutions.net> wrote: > > > > > On Fri, 2022-05-27 at 15:09 +0200, Dmitry Vyukov wrote: > > > > > > > I did note (this is more for kasan-dev@) that the "freed by" is fairly > > > > > > > much useless when using kfree_rcu(), it might be worthwhile to annotate > > > > > > > that somehow, so the stack trace is recorded by kfree_rcu() already, > > > > > > > rather than just showing the RCU callback used for that. > [...] > > Humm... I don't have any explanation based only on this info. > > Generally call_rcu stacks are memorized and I see the call is still there: > > https://elixir.bootlin.com/linux/v5.18/source/kernel/rcu/tree.c#L3595 > > Oh, that's simple then, UML is !SMP && !PREEMPT so it gets TINY_RCU > instead of TREE_RCU.
Nice!
> Unfortunately, it's not entirely trivial to fix, something like this, > mostly because of header maze (cannot include kasan.h in rcutiny.h): > > 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..aa235f0332ba 100644 > --- a/kernel/rcu/tiny.c > +++ b/kernel/rcu/tiny.c > @@ -217,6 +217,18 @@ bool poll_state_synchronize_rcu(unsigned long oldstate) > } > EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu); > > +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); > + > void __init rcu_init(void) > { > open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); > > > > > Or I guess I could copy/paste > > #ifdef CONFIG_KASAN_GENERIC > void kasan_record_aux_stack_noalloc(void *ptr); > #else /* CONFIG_KASAN_GENERIC */ > static inline void kasan_record_aux_stack_noalloc(void *ptr) {} > #endif /* CONFIG_KASAN_GENERIC */ > > > into rcutiny.h, that'd be smaller, and export the symbol ... > > johannes > > -- > 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@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/5eef2f1b43c25447ccca2f50f4964fd77a719b08.camel%40sipsolutions.net.
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