diff mbox series

[v3,32/35] codetag: debug: skip objext checking when it's for objext itself

Message ID 20240212213922.783301-33-surenb@google.com
State New
Headers
Series Memory allocation profiling |

Commit Message

Suren Baghdasaryan Feb. 12, 2024, 9:39 p.m. UTC 
  objext objects are created with __GFP_NO_OBJ_EXT flag and therefore have
no corresponding objext themselves (otherwise we would get an infinite
recursion). When freeing these objects their codetag will be empty and
when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled this will lead to false
warnings. Introduce CODETAG_EMPTY special codetag value to mark
allocations which intentionally lack codetag to avoid these warnings.
Set objext codetags to CODETAG_EMPTY before freeing to indicate that
the codetag is expected to be empty.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 include/linux/alloc_tag.h | 26 ++++++++++++++++++++++++++
 mm/slab.h                 | 25 +++++++++++++++++++++++++
 mm/slab_common.c          |  1 +
 mm/slub.c                 |  8 ++++++++
 4 files changed, 60 insertions(+)

Comments

Vlastimil Babka Feb. 16, 2024, 6:39 p.m. UTC | #1 
On 2/12/24 22:39, Suren Baghdasaryan wrote:
> objext objects are created with __GFP_NO_OBJ_EXT flag and therefore have
> no corresponding objext themselves (otherwise we would get an infinite
> recursion). When freeing these objects their codetag will be empty and
> when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled this will lead to false
> warnings. Introduce CODETAG_EMPTY special codetag value to mark
> allocations which intentionally lack codetag to avoid these warnings.
> Set objext codetags to CODETAG_EMPTY before freeing to indicate that
> the codetag is expected to be empty.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
>  include/linux/alloc_tag.h | 26 ++++++++++++++++++++++++++
>  mm/slab.h                 | 25 +++++++++++++++++++++++++
>  mm/slab_common.c          |  1 +
>  mm/slub.c                 |  8 ++++++++
>  4 files changed, 60 insertions(+)
> 
> diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
> index 0a5973c4ad77..1f3207097b03 100644

..

> index c4bd0d5348cb..cf332a839bf4 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
> @@ -567,6 +567,31 @@ static inline struct slabobj_ext *slab_obj_exts(struct slab *slab)
>  int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
>  			gfp_t gfp, bool new_slab);
>  
> +
> +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
> +
> +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts)
> +{
> +	struct slabobj_ext *slab_exts;
> +	struct slab *obj_exts_slab;
> +
> +	obj_exts_slab = virt_to_slab(obj_exts);
> +	slab_exts = slab_obj_exts(obj_exts_slab);
> +	if (slab_exts) {
> +		unsigned int offs = obj_to_index(obj_exts_slab->slab_cache,
> +						 obj_exts_slab, obj_exts);
> +		/* codetag should be NULL */
> +		WARN_ON(slab_exts[offs].ref.ct);
> +		set_codetag_empty(&slab_exts[offs].ref);
> +	}
> +}
> +
> +#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
> +
> +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {}
> +
> +#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
> +

I assume with alloc_slab_obj_exts() moved to slub.c, mark_objexts_empty()
could move there too.

>  static inline bool need_slab_obj_ext(void)
>  {
>  #ifdef CONFIG_MEM_ALLOC_PROFILING
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 21b0b9e9cd9e..d5f75d04ced2 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -242,6 +242,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
>  		 * assign slabobj_exts in parallel. In this case the existing
>  		 * objcg vector should be reused.
>  		 */
> +		mark_objexts_empty(vec);
>  		kfree(vec);
>  		return 0;
>  	}
> diff --git a/mm/slub.c b/mm/slub.c
> index 4d480784942e..1136ff18b4fe 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1890,6 +1890,14 @@ static inline void free_slab_obj_exts(struct slab *slab)
>  	if (!obj_exts)
>  		return;
>  
> +	/*
> +	 * obj_exts was created with __GFP_NO_OBJ_EXT flag, therefore its
> +	 * corresponding extension will be NULL. alloc_tag_sub() will throw a
> +	 * warning if slab has extensions but the extension of an object is
> +	 * NULL, therefore replace NULL with CODETAG_EMPTY to indicate that
> +	 * the extension for obj_exts is expected to be NULL.
> +	 */
> +	mark_objexts_empty(obj_exts);
>  	kfree(obj_exts);
>  	slab->obj_exts = 0;
>  }
Suren Baghdasaryan Feb. 19, 2024, 1:04 a.m. UTC | #2 
On Fri, Feb 16, 2024 at 6:39 PM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 2/12/24 22:39, Suren Baghdasaryan wrote:
> > objext objects are created with __GFP_NO_OBJ_EXT flag and therefore have
> > no corresponding objext themselves (otherwise we would get an infinite
> > recursion). When freeing these objects their codetag will be empty and
> > when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled this will lead to false
> > warnings. Introduce CODETAG_EMPTY special codetag value to mark
> > allocations which intentionally lack codetag to avoid these warnings.
> > Set objext codetags to CODETAG_EMPTY before freeing to indicate that
> > the codetag is expected to be empty.
> >
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> > ---
> >  include/linux/alloc_tag.h | 26 ++++++++++++++++++++++++++
> >  mm/slab.h                 | 25 +++++++++++++++++++++++++
> >  mm/slab_common.c          |  1 +
> >  mm/slub.c                 |  8 ++++++++
> >  4 files changed, 60 insertions(+)
> >
> > diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
> > index 0a5973c4ad77..1f3207097b03 100644
>
> ...
>
> > index c4bd0d5348cb..cf332a839bf4 100644
> > --- a/mm/slab.h
> > +++ b/mm/slab.h
> > @@ -567,6 +567,31 @@ static inline struct slabobj_ext *slab_obj_exts(struct slab *slab)
> >  int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> >                       gfp_t gfp, bool new_slab);
> >
> > +
> > +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
> > +
> > +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts)
> > +{
> > +     struct slabobj_ext *slab_exts;
> > +     struct slab *obj_exts_slab;
> > +
> > +     obj_exts_slab = virt_to_slab(obj_exts);
> > +     slab_exts = slab_obj_exts(obj_exts_slab);
> > +     if (slab_exts) {
> > +             unsigned int offs = obj_to_index(obj_exts_slab->slab_cache,
> > +                                              obj_exts_slab, obj_exts);
> > +             /* codetag should be NULL */
> > +             WARN_ON(slab_exts[offs].ref.ct);
> > +             set_codetag_empty(&slab_exts[offs].ref);
> > +     }
> > +}
> > +
> > +#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
> > +
> > +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {}
> > +
> > +#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
> > +
>
> I assume with alloc_slab_obj_exts() moved to slub.c, mark_objexts_empty()
> could move there too.

No, I think mark_objexts_empty() belongs here. This patch introduced
the function and uses it. Makes sense to me to keep it all together.

>
> >  static inline bool need_slab_obj_ext(void)
> >  {
> >  #ifdef CONFIG_MEM_ALLOC_PROFILING
> > diff --git a/mm/slab_common.c b/mm/slab_common.c
> > index 21b0b9e9cd9e..d5f75d04ced2 100644
> > --- a/mm/slab_common.c
> > +++ b/mm/slab_common.c
> > @@ -242,6 +242,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> >                * assign slabobj_exts in parallel. In this case the existing
> >                * objcg vector should be reused.
> >                */
> > +             mark_objexts_empty(vec);
> >               kfree(vec);
> >               return 0;
> >       }
> > diff --git a/mm/slub.c b/mm/slub.c
> > index 4d480784942e..1136ff18b4fe 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -1890,6 +1890,14 @@ static inline void free_slab_obj_exts(struct slab *slab)
> >       if (!obj_exts)
> >               return;
> >
> > +     /*
> > +      * obj_exts was created with __GFP_NO_OBJ_EXT flag, therefore its
> > +      * corresponding extension will be NULL. alloc_tag_sub() will throw a
> > +      * warning if slab has extensions but the extension of an object is
> > +      * NULL, therefore replace NULL with CODETAG_EMPTY to indicate that
> > +      * the extension for obj_exts is expected to be NULL.
> > +      */
> > +     mark_objexts_empty(obj_exts);
> >       kfree(obj_exts);
> >       slab->obj_exts = 0;
> >  }
>
Vlastimil Babka Feb. 19, 2024, 9:17 a.m. UTC | #3 
On 2/19/24 02:04, Suren Baghdasaryan wrote:
> On Fri, Feb 16, 2024 at 6:39 PM Vlastimil Babka <vbabka@suse.cz> wrote:
>>
>> On 2/12/24 22:39, Suren Baghdasaryan wrote:
>> > objext objects are created with __GFP_NO_OBJ_EXT flag and therefore have
>> > no corresponding objext themselves (otherwise we would get an infinite
>> > recursion). When freeing these objects their codetag will be empty and
>> > when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled this will lead to false
>> > warnings. Introduce CODETAG_EMPTY special codetag value to mark
>> > allocations which intentionally lack codetag to avoid these warnings.
>> > Set objext codetags to CODETAG_EMPTY before freeing to indicate that
>> > the codetag is expected to be empty.
>> >
>> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
>> > ---
>> >  include/linux/alloc_tag.h | 26 ++++++++++++++++++++++++++
>> >  mm/slab.h                 | 25 +++++++++++++++++++++++++
>> >  mm/slab_common.c          |  1 +
>> >  mm/slub.c                 |  8 ++++++++
>> >  4 files changed, 60 insertions(+)
>> >
>> > diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
>> > index 0a5973c4ad77..1f3207097b03 100644
>>
>> ...
>>
>> > index c4bd0d5348cb..cf332a839bf4 100644
>> > --- a/mm/slab.h
>> > +++ b/mm/slab.h
>> > @@ -567,6 +567,31 @@ static inline struct slabobj_ext *slab_obj_exts(struct slab *slab)
>> >  int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
>> >                       gfp_t gfp, bool new_slab);
>> >
>> > +
>> > +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
>> > +
>> > +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts)
>> > +{
>> > +     struct slabobj_ext *slab_exts;
>> > +     struct slab *obj_exts_slab;
>> > +
>> > +     obj_exts_slab = virt_to_slab(obj_exts);
>> > +     slab_exts = slab_obj_exts(obj_exts_slab);
>> > +     if (slab_exts) {
>> > +             unsigned int offs = obj_to_index(obj_exts_slab->slab_cache,
>> > +                                              obj_exts_slab, obj_exts);
>> > +             /* codetag should be NULL */
>> > +             WARN_ON(slab_exts[offs].ref.ct);
>> > +             set_codetag_empty(&slab_exts[offs].ref);
>> > +     }
>> > +}
>> > +
>> > +#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
>> > +
>> > +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {}
>> > +
>> > +#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
>> > +
>>
>> I assume with alloc_slab_obj_exts() moved to slub.c, mark_objexts_empty()
>> could move there too.
> 
> No, I think mark_objexts_empty() belongs here. This patch introduced
> the function and uses it. Makes sense to me to keep it all together.

Hi,

here I didn't mean moving between patches, but files. alloc_slab_obj_exts()
in slub.c means all callers of mark_objexts_empty() are in slub.c so it
doesn't need to be in slab.h

Also same thing with mark_failed_objexts_alloc() and
handle_failed_objexts_alloc() in patch 34/35.
Suren Baghdasaryan Feb. 19, 2024, 4:55 p.m. UTC | #4 
On Mon, Feb 19, 2024 at 1:17 AM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 2/19/24 02:04, Suren Baghdasaryan wrote:
> > On Fri, Feb 16, 2024 at 6:39 PM Vlastimil Babka <vbabka@suse.cz> wrote:
> >>
> >> On 2/12/24 22:39, Suren Baghdasaryan wrote:
> >> > objext objects are created with __GFP_NO_OBJ_EXT flag and therefore have
> >> > no corresponding objext themselves (otherwise we would get an infinite
> >> > recursion). When freeing these objects their codetag will be empty and
> >> > when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled this will lead to false
> >> > warnings. Introduce CODETAG_EMPTY special codetag value to mark
> >> > allocations which intentionally lack codetag to avoid these warnings.
> >> > Set objext codetags to CODETAG_EMPTY before freeing to indicate that
> >> > the codetag is expected to be empty.
> >> >
> >> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> >> > ---
> >> >  include/linux/alloc_tag.h | 26 ++++++++++++++++++++++++++
> >> >  mm/slab.h                 | 25 +++++++++++++++++++++++++
> >> >  mm/slab_common.c          |  1 +
> >> >  mm/slub.c                 |  8 ++++++++
> >> >  4 files changed, 60 insertions(+)
> >> >
> >> > diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
> >> > index 0a5973c4ad77..1f3207097b03 100644
> >>
> >> ...
> >>
> >> > index c4bd0d5348cb..cf332a839bf4 100644
> >> > --- a/mm/slab.h
> >> > +++ b/mm/slab.h
> >> > @@ -567,6 +567,31 @@ static inline struct slabobj_ext *slab_obj_exts(struct slab *slab)
> >> >  int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> >> >                       gfp_t gfp, bool new_slab);
> >> >
> >> > +
> >> > +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
> >> > +
> >> > +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts)
> >> > +{
> >> > +     struct slabobj_ext *slab_exts;
> >> > +     struct slab *obj_exts_slab;
> >> > +
> >> > +     obj_exts_slab = virt_to_slab(obj_exts);
> >> > +     slab_exts = slab_obj_exts(obj_exts_slab);
> >> > +     if (slab_exts) {
> >> > +             unsigned int offs = obj_to_index(obj_exts_slab->slab_cache,
> >> > +                                              obj_exts_slab, obj_exts);
> >> > +             /* codetag should be NULL */
> >> > +             WARN_ON(slab_exts[offs].ref.ct);
> >> > +             set_codetag_empty(&slab_exts[offs].ref);
> >> > +     }
> >> > +}
> >> > +
> >> > +#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
> >> > +
> >> > +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {}
> >> > +
> >> > +#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
> >> > +
> >>
> >> I assume with alloc_slab_obj_exts() moved to slub.c, mark_objexts_empty()
> >> could move there too.
> >
> > No, I think mark_objexts_empty() belongs here. This patch introduced
> > the function and uses it. Makes sense to me to keep it all together.
>
> Hi,
>
> here I didn't mean moving between patches, but files. alloc_slab_obj_exts()
> in slub.c means all callers of mark_objexts_empty() are in slub.c so it
> doesn't need to be in slab.h

Ah, I see. I misunderstood your comment. Yes, after slab/slob cleanup
this makes sense.

>
> Also same thing with mark_failed_objexts_alloc() and
> handle_failed_objexts_alloc() in patch 34/35.

Ack. Thanks!

>
diff mbox series

Patch

diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
index 0a5973c4ad77..1f3207097b03 100644
--- a/include/linux/alloc_tag.h
+++ b/include/linux/alloc_tag.h
@@ -77,6 +77,27 @@  static inline struct alloc_tag_counters alloc_tag_read(struct alloc_tag *tag)
 	return v;
 }
 
+#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
+
+#define CODETAG_EMPTY	(void *)1
+
+static inline bool is_codetag_empty(union codetag_ref *ref)
+{
+	return ref->ct == CODETAG_EMPTY;
+}
+
+static inline void set_codetag_empty(union codetag_ref *ref)
+{
+	if (ref)
+		ref->ct = CODETAG_EMPTY;
+}
+
+#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
+
+static inline bool is_codetag_empty(union codetag_ref *ref) { return false; }
+
+#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
+
 static inline void __alloc_tag_sub(union codetag_ref *ref, size_t bytes)
 {
 	struct alloc_tag *tag;
@@ -87,6 +108,11 @@  static inline void __alloc_tag_sub(union codetag_ref *ref, size_t bytes)
 	if (!ref || !ref->ct)
 		return;
 
+	if (is_codetag_empty(ref)) {
+		ref->ct = NULL;
+		return;
+	}
+
 	tag = ct_to_alloc_tag(ref->ct);
 
 	this_cpu_sub(tag->counters->bytes, bytes);
diff --git a/mm/slab.h b/mm/slab.h
index c4bd0d5348cb..cf332a839bf4 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -567,6 +567,31 @@  static inline struct slabobj_ext *slab_obj_exts(struct slab *slab)
 int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 			gfp_t gfp, bool new_slab);
 
+
+#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
+
+static inline void mark_objexts_empty(struct slabobj_ext *obj_exts)
+{
+	struct slabobj_ext *slab_exts;
+	struct slab *obj_exts_slab;
+
+	obj_exts_slab = virt_to_slab(obj_exts);
+	slab_exts = slab_obj_exts(obj_exts_slab);
+	if (slab_exts) {
+		unsigned int offs = obj_to_index(obj_exts_slab->slab_cache,
+						 obj_exts_slab, obj_exts);
+		/* codetag should be NULL */
+		WARN_ON(slab_exts[offs].ref.ct);
+		set_codetag_empty(&slab_exts[offs].ref);
+	}
+}
+
+#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
+
+static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {}
+
+#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
+
 static inline bool need_slab_obj_ext(void)
 {
 #ifdef CONFIG_MEM_ALLOC_PROFILING
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 21b0b9e9cd9e..d5f75d04ced2 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -242,6 +242,7 @@  int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 		 * assign slabobj_exts in parallel. In this case the existing
 		 * objcg vector should be reused.
 		 */
+		mark_objexts_empty(vec);
 		kfree(vec);
 		return 0;
 	}
diff --git a/mm/slub.c b/mm/slub.c
index 4d480784942e..1136ff18b4fe 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1890,6 +1890,14 @@  static inline void free_slab_obj_exts(struct slab *slab)
 	if (!obj_exts)
 		return;
 
+	/*
+	 * obj_exts was created with __GFP_NO_OBJ_EXT flag, therefore its
+	 * corresponding extension will be NULL. alloc_tag_sub() will throw a
+	 * warning if slab has extensions but the extension of an object is
+	 * NULL, therefore replace NULL with CODETAG_EMPTY to indicate that
+	 * the extension for obj_exts is expected to be NULL.
+	 */
+	mark_objexts_empty(obj_exts);
 	kfree(obj_exts);
 	slab->obj_exts = 0;
 }