diff mbox series

[v4,1/4] rcu/kasan: record and print call_rcu() call stack

Message ID 20200519022359.24115-1-walter-zh.wu@mediatek.com (mailing list archive)
State New, archived
Headers show
Series kasan: memorize and print call_rcu stack | expand

Commit Message

Walter Wu May 19, 2020, 2:23 a.m. UTC
This feature will record the last two call_rcu() call stacks and
prints up to 2 call_rcu() call stacks in KASAN report.

When call_rcu() is called, we store the call_rcu() call stack into
slub alloc meta-data, so that the KASAN report can print rcu stack.

[1]https://bugzilla.kernel.org/show_bug.cgi?id=198437
[2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ

Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
---
 include/linux/kasan.h |  2 ++
 kernel/rcu/tree.c     |  2 ++
 lib/Kconfig.kasan     |  2 ++
 mm/kasan/common.c     |  4 ++--
 mm/kasan/generic.c    | 19 +++++++++++++++++++
 mm/kasan/kasan.h      | 10 ++++++++++
 mm/kasan/report.c     | 24 ++++++++++++++++++++++++
 7 files changed, 61 insertions(+), 2 deletions(-)

Comments

Andrey Konovalov May 19, 2020, 2:52 p.m. UTC | #1
On Tue, May 19, 2020 at 4:24 AM Walter Wu <walter-zh.wu@mediatek.com> wrote:
>
> This feature will record the last two call_rcu() call stacks and
> prints up to 2 call_rcu() call stacks in KASAN report.
>
> When call_rcu() is called, we store the call_rcu() call stack into
> slub alloc meta-data, so that the KASAN report can print rcu stack.
>
> [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437
> [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ
>
> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
> Suggested-by: Dmitry Vyukov <dvyukov@google.com>
> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Paul E. McKenney <paulmck@kernel.org>
> Cc: Josh Triplett <josh@joshtriplett.org>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Cc: Lai Jiangshan <jiangshanlai@gmail.com>
> Cc: Joel Fernandes <joel@joelfernandes.org>
> ---
>  include/linux/kasan.h |  2 ++
>  kernel/rcu/tree.c     |  2 ++
>  lib/Kconfig.kasan     |  2 ++
>  mm/kasan/common.c     |  4 ++--
>  mm/kasan/generic.c    | 19 +++++++++++++++++++
>  mm/kasan/kasan.h      | 10 ++++++++++
>  mm/kasan/report.c     | 24 ++++++++++++++++++++++++
>  7 files changed, 61 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 31314ca7c635..23b7ee00572d 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -174,11 +174,13 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
>
>  void kasan_cache_shrink(struct kmem_cache *cache);
>  void kasan_cache_shutdown(struct kmem_cache *cache);
> +void kasan_record_aux_stack(void *ptr);
>
>  #else /* CONFIG_KASAN_GENERIC */
>
>  static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
>  static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
> +static inline void kasan_record_aux_stack(void *ptr) {}
>
>  #endif /* CONFIG_KASAN_GENERIC */
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 06548e2ebb72..36a4ff7f320b 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -57,6 +57,7 @@
>  #include <linux/slab.h>
>  #include <linux/sched/isolation.h>
>  #include <linux/sched/clock.h>
> +#include <linux/kasan.h>
>  #include "../time/tick-internal.h"
>
>  #include "tree.h"
> @@ -2668,6 +2669,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func)
>         head->func = func;
>         head->next = NULL;
>         local_irq_save(flags);
> +       kasan_record_aux_stack(head);
>         rdp = this_cpu_ptr(&rcu_data);
>
>         /* Add the callback to our list. */
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index 81f5464ea9e1..4e83cf6e3caa 100644
> --- a/lib/Kconfig.kasan
> +++ b/lib/Kconfig.kasan
> @@ -58,6 +58,8 @@ config KASAN_GENERIC
>           For better error detection enable CONFIG_STACKTRACE.
>           Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB
>           (the resulting kernel does not boot).
> +         In generic mode KASAN prints the last two call_rcu() call stacks in
> +         reports.

I don't think we need this here, mentioning this in the documentation is fine.


>
>  config KASAN_SW_TAGS
>         bool "Software tag-based mode"
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 2906358e42f0..8bc618289bb1 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -41,7 +41,7 @@
>  #include "kasan.h"
>  #include "../slab.h"
>
> -static inline depot_stack_handle_t save_stack(gfp_t flags)
> +depot_stack_handle_t kasan_save_stack(gfp_t flags)
>  {
>         unsigned long entries[KASAN_STACK_DEPTH];
>         unsigned int nr_entries;
> @@ -54,7 +54,7 @@ static inline depot_stack_handle_t save_stack(gfp_t flags)
>  static inline void set_track(struct kasan_track *track, gfp_t flags)
>  {
>         track->pid = current->pid;
> -       track->stack = save_stack(flags);
> +       track->stack = kasan_save_stack(flags);
>  }
>
>  void kasan_enable_current(void)
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index 56ff8885fe2e..3372bdcaf92a 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -325,3 +325,22 @@ DEFINE_ASAN_SET_SHADOW(f2);
>  DEFINE_ASAN_SET_SHADOW(f3);
>  DEFINE_ASAN_SET_SHADOW(f5);
>  DEFINE_ASAN_SET_SHADOW(f8);
> +
> +void kasan_record_aux_stack(void *addr)
> +{
> +       struct page *page = kasan_addr_to_page(addr);
> +       struct kmem_cache *cache;
> +       struct kasan_alloc_meta *alloc_info;
> +       void *object;
> +
> +       if (!(page && PageSlab(page)))
> +               return;
> +
> +       cache = page->slab_cache;
> +       object = nearest_obj(cache, page, addr);
> +       alloc_info = get_alloc_info(cache, object);
> +
> +       /* record the last two call_rcu() call stacks */
> +       alloc_info->aux_stack[1] = alloc_info->aux_stack[0];
> +       alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
> +}
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index e8f37199d885..a7391bc83070 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -104,7 +104,15 @@ struct kasan_track {
>
>  struct kasan_alloc_meta {
>         struct kasan_track alloc_track;
> +#ifdef CONFIG_KASAN_GENERIC
> +       /*
> +        * call_rcu() call stack is stored into struct kasan_alloc_meta.
> +        * The free stack is stored into struct kasan_free_meta.
> +        */
> +       depot_stack_handle_t aux_stack[2];
> +#else
>         struct kasan_track free_track[KASAN_NR_FREE_STACKS];
> +#endif
>  #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
>         u8 free_pointer_tag[KASAN_NR_FREE_STACKS];
>         u8 free_track_idx;
> @@ -159,6 +167,8 @@ void kasan_report_invalid_free(void *object, unsigned long ip);
>
>  struct page *kasan_addr_to_page(const void *addr);
>
> +depot_stack_handle_t kasan_save_stack(gfp_t flags);
> +
>  #if defined(CONFIG_KASAN_GENERIC) && \
>         (defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
>  void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache);
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 80f23c9da6b0..6f8f2bf8f53b 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -179,6 +179,17 @@ static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
>         return &alloc_meta->free_track[i];
>  }
>
> +#ifdef CONFIG_KASAN_GENERIC
> +static void print_stack(depot_stack_handle_t stack)

Let's put this function just before print_track() and reuse there.

> +{
> +       unsigned long *entries;
> +       unsigned int nr_entries;
> +
> +       nr_entries = stack_depot_fetch(stack, &entries);
> +       stack_trace_print(entries, nr_entries, 0);
> +}
> +#endif
> +
>  static void describe_object(struct kmem_cache *cache, void *object,
>                                 const void *addr, u8 tag)
>  {
> @@ -192,6 +203,19 @@ static void describe_object(struct kmem_cache *cache, void *object,
>                 free_track = kasan_get_free_track(cache, object, tag);
>                 print_track(free_track, "Freed");
>                 pr_err("\n");
> +
> +#ifdef CONFIG_KASAN_GENERIC
> +               if (alloc_info->aux_stack[0]) {
> +                       pr_err("Last one call_rcu() call stack:\n");

Could you change this to "Last call_rcu():\n",

> +                       print_stack(alloc_info->aux_stack[0]);
> +                       pr_err("\n");
> +               }
> +               if (alloc_info->aux_stack[1]) {
> +                       pr_err("Second to last call_rcu() call stack:\n");

and this to "Second to last call_rcu():\n"?

It's shorter, but provides the same info.



> +                       print_stack(alloc_info->aux_stack[1]);
> +                       pr_err("\n");
> +               }
> +#endif
>         }
>
>         describe_object_addr(cache, object, addr);
> --
> 2.18.0
>
> --
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Paul E. McKenney May 19, 2020, 3:48 p.m. UTC | #2
On Tue, May 19, 2020 at 10:23:59AM +0800, Walter Wu wrote:
> This feature will record the last two call_rcu() call stacks and
> prints up to 2 call_rcu() call stacks in KASAN report.
> 
> When call_rcu() is called, we store the call_rcu() call stack into
> slub alloc meta-data, so that the KASAN report can print rcu stack.
> 
> [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437
> [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ
> 
> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
> Suggested-by: Dmitry Vyukov <dvyukov@google.com>
> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Paul E. McKenney <paulmck@kernel.org>
> Cc: Josh Triplett <josh@joshtriplett.org>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Cc: Lai Jiangshan <jiangshanlai@gmail.com>
> Cc: Joel Fernandes <joel@joelfernandes.org>

From an RCU perspective:

Acked-by: Paul E. McKenney <paulmck@kernel.org>

> ---
>  include/linux/kasan.h |  2 ++
>  kernel/rcu/tree.c     |  2 ++
>  lib/Kconfig.kasan     |  2 ++
>  mm/kasan/common.c     |  4 ++--
>  mm/kasan/generic.c    | 19 +++++++++++++++++++
>  mm/kasan/kasan.h      | 10 ++++++++++
>  mm/kasan/report.c     | 24 ++++++++++++++++++++++++
>  7 files changed, 61 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 31314ca7c635..23b7ee00572d 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -174,11 +174,13 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
>  
>  void kasan_cache_shrink(struct kmem_cache *cache);
>  void kasan_cache_shutdown(struct kmem_cache *cache);
> +void kasan_record_aux_stack(void *ptr);
>  
>  #else /* CONFIG_KASAN_GENERIC */
>  
>  static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
>  static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
> +static inline void kasan_record_aux_stack(void *ptr) {}
>  
>  #endif /* CONFIG_KASAN_GENERIC */
>  
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 06548e2ebb72..36a4ff7f320b 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -57,6 +57,7 @@
>  #include <linux/slab.h>
>  #include <linux/sched/isolation.h>
>  #include <linux/sched/clock.h>
> +#include <linux/kasan.h>
>  #include "../time/tick-internal.h"
>  
>  #include "tree.h"
> @@ -2668,6 +2669,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func)
>  	head->func = func;
>  	head->next = NULL;
>  	local_irq_save(flags);
> +	kasan_record_aux_stack(head);
>  	rdp = this_cpu_ptr(&rcu_data);
>  
>  	/* Add the callback to our list. */
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index 81f5464ea9e1..4e83cf6e3caa 100644
> --- a/lib/Kconfig.kasan
> +++ b/lib/Kconfig.kasan
> @@ -58,6 +58,8 @@ config KASAN_GENERIC
>  	  For better error detection enable CONFIG_STACKTRACE.
>  	  Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB
>  	  (the resulting kernel does not boot).
> +	  In generic mode KASAN prints the last two call_rcu() call stacks in
> +	  reports.
>  
>  config KASAN_SW_TAGS
>  	bool "Software tag-based mode"
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 2906358e42f0..8bc618289bb1 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -41,7 +41,7 @@
>  #include "kasan.h"
>  #include "../slab.h"
>  
> -static inline depot_stack_handle_t save_stack(gfp_t flags)
> +depot_stack_handle_t kasan_save_stack(gfp_t flags)
>  {
>  	unsigned long entries[KASAN_STACK_DEPTH];
>  	unsigned int nr_entries;
> @@ -54,7 +54,7 @@ static inline depot_stack_handle_t save_stack(gfp_t flags)
>  static inline void set_track(struct kasan_track *track, gfp_t flags)
>  {
>  	track->pid = current->pid;
> -	track->stack = save_stack(flags);
> +	track->stack = kasan_save_stack(flags);
>  }
>  
>  void kasan_enable_current(void)
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index 56ff8885fe2e..3372bdcaf92a 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -325,3 +325,22 @@ DEFINE_ASAN_SET_SHADOW(f2);
>  DEFINE_ASAN_SET_SHADOW(f3);
>  DEFINE_ASAN_SET_SHADOW(f5);
>  DEFINE_ASAN_SET_SHADOW(f8);
> +
> +void kasan_record_aux_stack(void *addr)
> +{
> +	struct page *page = kasan_addr_to_page(addr);
> +	struct kmem_cache *cache;
> +	struct kasan_alloc_meta *alloc_info;
> +	void *object;
> +
> +	if (!(page && PageSlab(page)))
> +		return;
> +
> +	cache = page->slab_cache;
> +	object = nearest_obj(cache, page, addr);
> +	alloc_info = get_alloc_info(cache, object);
> +
> +	/* record the last two call_rcu() call stacks */
> +	alloc_info->aux_stack[1] = alloc_info->aux_stack[0];
> +	alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
> +}
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index e8f37199d885..a7391bc83070 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -104,7 +104,15 @@ struct kasan_track {
>  
>  struct kasan_alloc_meta {
>  	struct kasan_track alloc_track;
> +#ifdef CONFIG_KASAN_GENERIC
> +	/*
> +	 * call_rcu() call stack is stored into struct kasan_alloc_meta.
> +	 * The free stack is stored into struct kasan_free_meta.
> +	 */
> +	depot_stack_handle_t aux_stack[2];
> +#else
>  	struct kasan_track free_track[KASAN_NR_FREE_STACKS];
> +#endif
>  #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
>  	u8 free_pointer_tag[KASAN_NR_FREE_STACKS];
>  	u8 free_track_idx;
> @@ -159,6 +167,8 @@ void kasan_report_invalid_free(void *object, unsigned long ip);
>  
>  struct page *kasan_addr_to_page(const void *addr);
>  
> +depot_stack_handle_t kasan_save_stack(gfp_t flags);
> +
>  #if defined(CONFIG_KASAN_GENERIC) && \
>  	(defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
>  void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache);
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 80f23c9da6b0..6f8f2bf8f53b 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -179,6 +179,17 @@ static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
>  	return &alloc_meta->free_track[i];
>  }
>  
> +#ifdef CONFIG_KASAN_GENERIC
> +static void print_stack(depot_stack_handle_t stack)
> +{
> +	unsigned long *entries;
> +	unsigned int nr_entries;
> +
> +	nr_entries = stack_depot_fetch(stack, &entries);
> +	stack_trace_print(entries, nr_entries, 0);
> +}
> +#endif
> +
>  static void describe_object(struct kmem_cache *cache, void *object,
>  				const void *addr, u8 tag)
>  {
> @@ -192,6 +203,19 @@ static void describe_object(struct kmem_cache *cache, void *object,
>  		free_track = kasan_get_free_track(cache, object, tag);
>  		print_track(free_track, "Freed");
>  		pr_err("\n");
> +
> +#ifdef CONFIG_KASAN_GENERIC
> +		if (alloc_info->aux_stack[0]) {
> +			pr_err("Last one call_rcu() call stack:\n");
> +			print_stack(alloc_info->aux_stack[0]);
> +			pr_err("\n");
> +		}
> +		if (alloc_info->aux_stack[1]) {
> +			pr_err("Second to last call_rcu() call stack:\n");
> +			print_stack(alloc_info->aux_stack[1]);
> +			pr_err("\n");
> +		}
> +#endif
>  	}
>  
>  	describe_object_addr(cache, object, addr);
> -- 
> 2.18.0
Walter Wu May 20, 2020, 2:45 a.m. UTC | #3
Hi Andrey,

On Tue, 2020-05-19 at 16:52 +0200, 'Andrey Konovalov' via kasan-dev
wrote:
> On Tue, May 19, 2020 at 4:24 AM Walter Wu <walter-zh.wu@mediatek.com> wrote:
> >
> > This feature will record the last two call_rcu() call stacks and
> > prints up to 2 call_rcu() call stacks in KASAN report.
> >
> > When call_rcu() is called, we store the call_rcu() call stack into
> > slub alloc meta-data, so that the KASAN report can print rcu stack.
> >
> > [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437
> > [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ
> >
> > Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
> > Suggested-by: Dmitry Vyukov <dvyukov@google.com>
> > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> > Cc: Dmitry Vyukov <dvyukov@google.com>
> > Cc: Alexander Potapenko <glider@google.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Paul E. McKenney <paulmck@kernel.org>
> > Cc: Josh Triplett <josh@joshtriplett.org>
> > Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> > Cc: Lai Jiangshan <jiangshanlai@gmail.com>
> > Cc: Joel Fernandes <joel@joelfernandes.org>
> > ---
> >  include/linux/kasan.h |  2 ++
> >  kernel/rcu/tree.c     |  2 ++
> >  lib/Kconfig.kasan     |  2 ++
> >  mm/kasan/common.c     |  4 ++--
> >  mm/kasan/generic.c    | 19 +++++++++++++++++++
> >  mm/kasan/kasan.h      | 10 ++++++++++
> >  mm/kasan/report.c     | 24 ++++++++++++++++++++++++
> >  7 files changed, 61 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> > index 31314ca7c635..23b7ee00572d 100644
> > --- a/include/linux/kasan.h
> > +++ b/include/linux/kasan.h
> > @@ -174,11 +174,13 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
> >
> >  void kasan_cache_shrink(struct kmem_cache *cache);
> >  void kasan_cache_shutdown(struct kmem_cache *cache);
> > +void kasan_record_aux_stack(void *ptr);
> >
> >  #else /* CONFIG_KASAN_GENERIC */
> >
> >  static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
> >  static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
> > +static inline void kasan_record_aux_stack(void *ptr) {}
> >
> >  #endif /* CONFIG_KASAN_GENERIC */
> >
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 06548e2ebb72..36a4ff7f320b 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -57,6 +57,7 @@
> >  #include <linux/slab.h>
> >  #include <linux/sched/isolation.h>
> >  #include <linux/sched/clock.h>
> > +#include <linux/kasan.h>
> >  #include "../time/tick-internal.h"
> >
> >  #include "tree.h"
> > @@ -2668,6 +2669,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func)
> >         head->func = func;
> >         head->next = NULL;
> >         local_irq_save(flags);
> > +       kasan_record_aux_stack(head);
> >         rdp = this_cpu_ptr(&rcu_data);
> >
> >         /* Add the callback to our list. */
> > diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> > index 81f5464ea9e1..4e83cf6e3caa 100644
> > --- a/lib/Kconfig.kasan
> > +++ b/lib/Kconfig.kasan
> > @@ -58,6 +58,8 @@ config KASAN_GENERIC
> >           For better error detection enable CONFIG_STACKTRACE.
> >           Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB
> >           (the resulting kernel does not boot).
> > +         In generic mode KASAN prints the last two call_rcu() call stacks in
> > +         reports.
> 
> I don't think we need this here, mentioning this in the documentation is fine.
> 

Ok, we will remove it. Only mention it in the documentation.

> 
> >
> >  config KASAN_SW_TAGS
> >         bool "Software tag-based mode"
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index 2906358e42f0..8bc618289bb1 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -41,7 +41,7 @@
> >  #include "kasan.h"
> >  #include "../slab.h"
> >
> > -static inline depot_stack_handle_t save_stack(gfp_t flags)
> > +depot_stack_handle_t kasan_save_stack(gfp_t flags)
> >  {
> >         unsigned long entries[KASAN_STACK_DEPTH];
> >         unsigned int nr_entries;
> > @@ -54,7 +54,7 @@ static inline depot_stack_handle_t save_stack(gfp_t flags)
> >  static inline void set_track(struct kasan_track *track, gfp_t flags)
> >  {
> >         track->pid = current->pid;
> > -       track->stack = save_stack(flags);
> > +       track->stack = kasan_save_stack(flags);
> >  }
> >
> >  void kasan_enable_current(void)
> > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> > index 56ff8885fe2e..3372bdcaf92a 100644
> > --- a/mm/kasan/generic.c
> > +++ b/mm/kasan/generic.c
> > @@ -325,3 +325,22 @@ DEFINE_ASAN_SET_SHADOW(f2);
> >  DEFINE_ASAN_SET_SHADOW(f3);
> >  DEFINE_ASAN_SET_SHADOW(f5);
> >  DEFINE_ASAN_SET_SHADOW(f8);
> > +
> > +void kasan_record_aux_stack(void *addr)
> > +{
> > +       struct page *page = kasan_addr_to_page(addr);
> > +       struct kmem_cache *cache;
> > +       struct kasan_alloc_meta *alloc_info;
> > +       void *object;
> > +
> > +       if (!(page && PageSlab(page)))
> > +               return;
> > +
> > +       cache = page->slab_cache;
> > +       object = nearest_obj(cache, page, addr);
> > +       alloc_info = get_alloc_info(cache, object);
> > +
> > +       /* record the last two call_rcu() call stacks */
> > +       alloc_info->aux_stack[1] = alloc_info->aux_stack[0];
> > +       alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
> > +}
> > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> > index e8f37199d885..a7391bc83070 100644
> > --- a/mm/kasan/kasan.h
> > +++ b/mm/kasan/kasan.h
> > @@ -104,7 +104,15 @@ struct kasan_track {
> >
> >  struct kasan_alloc_meta {
> >         struct kasan_track alloc_track;
> > +#ifdef CONFIG_KASAN_GENERIC
> > +       /*
> > +        * call_rcu() call stack is stored into struct kasan_alloc_meta.
> > +        * The free stack is stored into struct kasan_free_meta.
> > +        */
> > +       depot_stack_handle_t aux_stack[2];
> > +#else
> >         struct kasan_track free_track[KASAN_NR_FREE_STACKS];
> > +#endif
> >  #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
> >         u8 free_pointer_tag[KASAN_NR_FREE_STACKS];
> >         u8 free_track_idx;
> > @@ -159,6 +167,8 @@ void kasan_report_invalid_free(void *object, unsigned long ip);
> >
> >  struct page *kasan_addr_to_page(const void *addr);
> >
> > +depot_stack_handle_t kasan_save_stack(gfp_t flags);
> > +
> >  #if defined(CONFIG_KASAN_GENERIC) && \
> >         (defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
> >  void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache);
> > diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> > index 80f23c9da6b0..6f8f2bf8f53b 100644
> > --- a/mm/kasan/report.c
> > +++ b/mm/kasan/report.c
> > @@ -179,6 +179,17 @@ static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
> >         return &alloc_meta->free_track[i];
> >  }
> >
> > +#ifdef CONFIG_KASAN_GENERIC
> > +static void print_stack(depot_stack_handle_t stack)
> 
> Let's put this function just before print_track() and reuse there.
> 

Ok.

> > +{
> > +       unsigned long *entries;
> > +       unsigned int nr_entries;
> > +
> > +       nr_entries = stack_depot_fetch(stack, &entries);
> > +       stack_trace_print(entries, nr_entries, 0);
> > +}
> > +#endif
> > +
> >  static void describe_object(struct kmem_cache *cache, void *object,
> >                                 const void *addr, u8 tag)
> >  {
> > @@ -192,6 +203,19 @@ static void describe_object(struct kmem_cache *cache, void *object,
> >                 free_track = kasan_get_free_track(cache, object, tag);
> >                 print_track(free_track, "Freed");
> >                 pr_err("\n");
> > +
> > +#ifdef CONFIG_KASAN_GENERIC
> > +               if (alloc_info->aux_stack[0]) {
> > +                       pr_err("Last one call_rcu() call stack:\n");
> 
> Could you change this to "Last call_rcu():\n",
> 
> > +                       print_stack(alloc_info->aux_stack[0]);
> > +                       pr_err("\n");
> > +               }
> > +               if (alloc_info->aux_stack[1]) {
> > +                       pr_err("Second to last call_rcu() call stack:\n");
> 
> and this to "Second to last call_rcu():\n"?
> 
> It's shorter, but provides the same info.
> 

We will change their name.

Thank you for your review.

> 
> 
> > +                       print_stack(alloc_info->aux_stack[1]);
> > +                       pr_err("\n");
> > +               }
> > +#endif
> >         }
> >
> >         describe_object_addr(cache, object, addr);
> > --
> > 2.18.0
> >
> > --
> > 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/20200519022359.24115-1-walter-zh.wu%40mediatek.com.
>
Walter Wu May 20, 2020, 2:49 a.m. UTC | #4
On Tue, 2020-05-19 at 08:48 -0700, Paul E. McKenney wrote:
> On Tue, May 19, 2020 at 10:23:59AM +0800, Walter Wu wrote:
> > This feature will record the last two call_rcu() call stacks and
> > prints up to 2 call_rcu() call stacks in KASAN report.
> > 
> > When call_rcu() is called, we store the call_rcu() call stack into
> > slub alloc meta-data, so that the KASAN report can print rcu stack.
> > 
> > [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437
> > [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ
> > 
> > Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
> > Suggested-by: Dmitry Vyukov <dvyukov@google.com>
> > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> > Cc: Dmitry Vyukov <dvyukov@google.com>
> > Cc: Alexander Potapenko <glider@google.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Paul E. McKenney <paulmck@kernel.org>
> > Cc: Josh Triplett <josh@joshtriplett.org>
> > Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> > Cc: Lai Jiangshan <jiangshanlai@gmail.com>
> > Cc: Joel Fernandes <joel@joelfernandes.org>
> 
> From an RCU perspective:
> 
> Acked-by: Paul E. McKenney <paulmck@kernel.org>
> 

Hi Paul,

Thank you for your suggestion and review.


Walter

> > ---
> >  include/linux/kasan.h |  2 ++
> >  kernel/rcu/tree.c     |  2 ++
> >  lib/Kconfig.kasan     |  2 ++
> >  mm/kasan/common.c     |  4 ++--
> >  mm/kasan/generic.c    | 19 +++++++++++++++++++
> >  mm/kasan/kasan.h      | 10 ++++++++++
> >  mm/kasan/report.c     | 24 ++++++++++++++++++++++++
> >  7 files changed, 61 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> > index 31314ca7c635..23b7ee00572d 100644
> > --- a/include/linux/kasan.h
> > +++ b/include/linux/kasan.h
> > @@ -174,11 +174,13 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
> >  
> >  void kasan_cache_shrink(struct kmem_cache *cache);
> >  void kasan_cache_shutdown(struct kmem_cache *cache);
> > +void kasan_record_aux_stack(void *ptr);
> >  
> >  #else /* CONFIG_KASAN_GENERIC */
> >  
> >  static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
> >  static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
> > +static inline void kasan_record_aux_stack(void *ptr) {}
> >  
> >  #endif /* CONFIG_KASAN_GENERIC */
> >  
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 06548e2ebb72..36a4ff7f320b 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -57,6 +57,7 @@
> >  #include <linux/slab.h>
> >  #include <linux/sched/isolation.h>
> >  #include <linux/sched/clock.h>
> > +#include <linux/kasan.h>
> >  #include "../time/tick-internal.h"
> >  
> >  #include "tree.h"
> > @@ -2668,6 +2669,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func)
> >  	head->func = func;
> >  	head->next = NULL;
> >  	local_irq_save(flags);
> > +	kasan_record_aux_stack(head);
> >  	rdp = this_cpu_ptr(&rcu_data);
> >  
> >  	/* Add the callback to our list. */
> > diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> > index 81f5464ea9e1..4e83cf6e3caa 100644
> > --- a/lib/Kconfig.kasan
> > +++ b/lib/Kconfig.kasan
> > @@ -58,6 +58,8 @@ config KASAN_GENERIC
> >  	  For better error detection enable CONFIG_STACKTRACE.
> >  	  Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB
> >  	  (the resulting kernel does not boot).
> > +	  In generic mode KASAN prints the last two call_rcu() call stacks in
> > +	  reports.
> >  
> >  config KASAN_SW_TAGS
> >  	bool "Software tag-based mode"
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index 2906358e42f0..8bc618289bb1 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -41,7 +41,7 @@
> >  #include "kasan.h"
> >  #include "../slab.h"
> >  
> > -static inline depot_stack_handle_t save_stack(gfp_t flags)
> > +depot_stack_handle_t kasan_save_stack(gfp_t flags)
> >  {
> >  	unsigned long entries[KASAN_STACK_DEPTH];
> >  	unsigned int nr_entries;
> > @@ -54,7 +54,7 @@ static inline depot_stack_handle_t save_stack(gfp_t flags)
> >  static inline void set_track(struct kasan_track *track, gfp_t flags)
> >  {
> >  	track->pid = current->pid;
> > -	track->stack = save_stack(flags);
> > +	track->stack = kasan_save_stack(flags);
> >  }
> >  
> >  void kasan_enable_current(void)
> > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> > index 56ff8885fe2e..3372bdcaf92a 100644
> > --- a/mm/kasan/generic.c
> > +++ b/mm/kasan/generic.c
> > @@ -325,3 +325,22 @@ DEFINE_ASAN_SET_SHADOW(f2);
> >  DEFINE_ASAN_SET_SHADOW(f3);
> >  DEFINE_ASAN_SET_SHADOW(f5);
> >  DEFINE_ASAN_SET_SHADOW(f8);
> > +
> > +void kasan_record_aux_stack(void *addr)
> > +{
> > +	struct page *page = kasan_addr_to_page(addr);
> > +	struct kmem_cache *cache;
> > +	struct kasan_alloc_meta *alloc_info;
> > +	void *object;
> > +
> > +	if (!(page && PageSlab(page)))
> > +		return;
> > +
> > +	cache = page->slab_cache;
> > +	object = nearest_obj(cache, page, addr);
> > +	alloc_info = get_alloc_info(cache, object);
> > +
> > +	/* record the last two call_rcu() call stacks */
> > +	alloc_info->aux_stack[1] = alloc_info->aux_stack[0];
> > +	alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
> > +}
> > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> > index e8f37199d885..a7391bc83070 100644
> > --- a/mm/kasan/kasan.h
> > +++ b/mm/kasan/kasan.h
> > @@ -104,7 +104,15 @@ struct kasan_track {
> >  
> >  struct kasan_alloc_meta {
> >  	struct kasan_track alloc_track;
> > +#ifdef CONFIG_KASAN_GENERIC
> > +	/*
> > +	 * call_rcu() call stack is stored into struct kasan_alloc_meta.
> > +	 * The free stack is stored into struct kasan_free_meta.
> > +	 */
> > +	depot_stack_handle_t aux_stack[2];
> > +#else
> >  	struct kasan_track free_track[KASAN_NR_FREE_STACKS];
> > +#endif
> >  #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
> >  	u8 free_pointer_tag[KASAN_NR_FREE_STACKS];
> >  	u8 free_track_idx;
> > @@ -159,6 +167,8 @@ void kasan_report_invalid_free(void *object, unsigned long ip);
> >  
> >  struct page *kasan_addr_to_page(const void *addr);
> >  
> > +depot_stack_handle_t kasan_save_stack(gfp_t flags);
> > +
> >  #if defined(CONFIG_KASAN_GENERIC) && \
> >  	(defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
> >  void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache);
> > diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> > index 80f23c9da6b0..6f8f2bf8f53b 100644
> > --- a/mm/kasan/report.c
> > +++ b/mm/kasan/report.c
> > @@ -179,6 +179,17 @@ static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
> >  	return &alloc_meta->free_track[i];
> >  }
> >  
> > +#ifdef CONFIG_KASAN_GENERIC
> > +static void print_stack(depot_stack_handle_t stack)
> > +{
> > +	unsigned long *entries;
> > +	unsigned int nr_entries;
> > +
> > +	nr_entries = stack_depot_fetch(stack, &entries);
> > +	stack_trace_print(entries, nr_entries, 0);
> > +}
> > +#endif
> > +
> >  static void describe_object(struct kmem_cache *cache, void *object,
> >  				const void *addr, u8 tag)
> >  {
> > @@ -192,6 +203,19 @@ static void describe_object(struct kmem_cache *cache, void *object,
> >  		free_track = kasan_get_free_track(cache, object, tag);
> >  		print_track(free_track, "Freed");
> >  		pr_err("\n");
> > +
> > +#ifdef CONFIG_KASAN_GENERIC
> > +		if (alloc_info->aux_stack[0]) {
> > +			pr_err("Last one call_rcu() call stack:\n");
> > +			print_stack(alloc_info->aux_stack[0]);
> > +			pr_err("\n");
> > +		}
> > +		if (alloc_info->aux_stack[1]) {
> > +			pr_err("Second to last call_rcu() call stack:\n");
> > +			print_stack(alloc_info->aux_stack[1]);
> > +			pr_err("\n");
> > +		}
> > +#endif
> >  	}
> >  
> >  	describe_object_addr(cache, object, addr);
> > -- 
> > 2.18.0
diff mbox series

Patch

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 31314ca7c635..23b7ee00572d 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -174,11 +174,13 @@  static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
 
 void kasan_cache_shrink(struct kmem_cache *cache);
 void kasan_cache_shutdown(struct kmem_cache *cache);
+void kasan_record_aux_stack(void *ptr);
 
 #else /* CONFIG_KASAN_GENERIC */
 
 static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
 static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
+static inline void kasan_record_aux_stack(void *ptr) {}
 
 #endif /* CONFIG_KASAN_GENERIC */
 
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 06548e2ebb72..36a4ff7f320b 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -57,6 +57,7 @@ 
 #include <linux/slab.h>
 #include <linux/sched/isolation.h>
 #include <linux/sched/clock.h>
+#include <linux/kasan.h>
 #include "../time/tick-internal.h"
 
 #include "tree.h"
@@ -2668,6 +2669,7 @@  __call_rcu(struct rcu_head *head, rcu_callback_t func)
 	head->func = func;
 	head->next = NULL;
 	local_irq_save(flags);
+	kasan_record_aux_stack(head);
 	rdp = this_cpu_ptr(&rcu_data);
 
 	/* Add the callback to our list. */
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 81f5464ea9e1..4e83cf6e3caa 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -58,6 +58,8 @@  config KASAN_GENERIC
 	  For better error detection enable CONFIG_STACKTRACE.
 	  Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB
 	  (the resulting kernel does not boot).
+	  In generic mode KASAN prints the last two call_rcu() call stacks in
+	  reports.
 
 config KASAN_SW_TAGS
 	bool "Software tag-based mode"
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 2906358e42f0..8bc618289bb1 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -41,7 +41,7 @@ 
 #include "kasan.h"
 #include "../slab.h"
 
-static inline depot_stack_handle_t save_stack(gfp_t flags)
+depot_stack_handle_t kasan_save_stack(gfp_t flags)
 {
 	unsigned long entries[KASAN_STACK_DEPTH];
 	unsigned int nr_entries;
@@ -54,7 +54,7 @@  static inline depot_stack_handle_t save_stack(gfp_t flags)
 static inline void set_track(struct kasan_track *track, gfp_t flags)
 {
 	track->pid = current->pid;
-	track->stack = save_stack(flags);
+	track->stack = kasan_save_stack(flags);
 }
 
 void kasan_enable_current(void)
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 56ff8885fe2e..3372bdcaf92a 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -325,3 +325,22 @@  DEFINE_ASAN_SET_SHADOW(f2);
 DEFINE_ASAN_SET_SHADOW(f3);
 DEFINE_ASAN_SET_SHADOW(f5);
 DEFINE_ASAN_SET_SHADOW(f8);
+
+void kasan_record_aux_stack(void *addr)
+{
+	struct page *page = kasan_addr_to_page(addr);
+	struct kmem_cache *cache;
+	struct kasan_alloc_meta *alloc_info;
+	void *object;
+
+	if (!(page && PageSlab(page)))
+		return;
+
+	cache = page->slab_cache;
+	object = nearest_obj(cache, page, addr);
+	alloc_info = get_alloc_info(cache, object);
+
+	/* record the last two call_rcu() call stacks */
+	alloc_info->aux_stack[1] = alloc_info->aux_stack[0];
+	alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
+}
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index e8f37199d885..a7391bc83070 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -104,7 +104,15 @@  struct kasan_track {
 
 struct kasan_alloc_meta {
 	struct kasan_track alloc_track;
+#ifdef CONFIG_KASAN_GENERIC
+	/*
+	 * call_rcu() call stack is stored into struct kasan_alloc_meta.
+	 * The free stack is stored into struct kasan_free_meta.
+	 */
+	depot_stack_handle_t aux_stack[2];
+#else
 	struct kasan_track free_track[KASAN_NR_FREE_STACKS];
+#endif
 #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
 	u8 free_pointer_tag[KASAN_NR_FREE_STACKS];
 	u8 free_track_idx;
@@ -159,6 +167,8 @@  void kasan_report_invalid_free(void *object, unsigned long ip);
 
 struct page *kasan_addr_to_page(const void *addr);
 
+depot_stack_handle_t kasan_save_stack(gfp_t flags);
+
 #if defined(CONFIG_KASAN_GENERIC) && \
 	(defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
 void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache);
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 80f23c9da6b0..6f8f2bf8f53b 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -179,6 +179,17 @@  static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
 	return &alloc_meta->free_track[i];
 }
 
+#ifdef CONFIG_KASAN_GENERIC
+static void print_stack(depot_stack_handle_t stack)
+{
+	unsigned long *entries;
+	unsigned int nr_entries;
+
+	nr_entries = stack_depot_fetch(stack, &entries);
+	stack_trace_print(entries, nr_entries, 0);
+}
+#endif
+
 static void describe_object(struct kmem_cache *cache, void *object,
 				const void *addr, u8 tag)
 {
@@ -192,6 +203,19 @@  static void describe_object(struct kmem_cache *cache, void *object,
 		free_track = kasan_get_free_track(cache, object, tag);
 		print_track(free_track, "Freed");
 		pr_err("\n");
+
+#ifdef CONFIG_KASAN_GENERIC
+		if (alloc_info->aux_stack[0]) {
+			pr_err("Last one call_rcu() call stack:\n");
+			print_stack(alloc_info->aux_stack[0]);
+			pr_err("\n");
+		}
+		if (alloc_info->aux_stack[1]) {
+			pr_err("Second to last call_rcu() call stack:\n");
+			print_stack(alloc_info->aux_stack[1]);
+			pr_err("\n");
+		}
+#endif
 	}
 
 	describe_object_addr(cache, object, addr);