diff mbox series

[v3,4/6] mm/slub: distinguish and print stack traces in debugfs files

Message ID 20220404164112.18372-5-vbabka@suse.cz (mailing list archive)
State New
Headers show
Series SLUB debugfs improvements based on stackdepot | expand

Commit Message

Vlastimil Babka April 4, 2022, 4:41 p.m. UTC 
From: Oliver Glitta <glittao@gmail.com>

Aggregate objects in slub cache by unique stack trace in addition to
caller address when producing contents of debugfs files alloc_traces and
free_traces in debugfs. Also add the stack traces to the debugfs output.
This makes it much more useful to e.g. debug memory leaks.

Signed-off-by: Oliver Glitta <glittao@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-and-tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
---
 mm/slub.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

Comments

David Rientjes April 5, 2022, 9:40 p.m. UTC | #1 
On Mon, 4 Apr 2022, Vlastimil Babka wrote:

> From: Oliver Glitta <glittao@gmail.com>
> 
> Aggregate objects in slub cache by unique stack trace in addition to
> caller address when producing contents of debugfs files alloc_traces and
> free_traces in debugfs. Also add the stack traces to the debugfs output.
> This makes it much more useful to e.g. debug memory leaks.
> 
> Signed-off-by: Oliver Glitta <glittao@gmail.com>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> Reviewed-and-tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> ---
>  mm/slub.c | 28 ++++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 98c1450c23f0..f2e550e1adf0 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -5064,6 +5064,7 @@ EXPORT_SYMBOL(validate_slab_cache);
>   */
>  
>  struct location {
> +	depot_stack_handle_t handle;
>  	unsigned long count;
>  	unsigned long addr;
>  	long long sum_time;
> @@ -5116,9 +5117,13 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
>  {
>  	long start, end, pos;
>  	struct location *l;
> -	unsigned long caddr;
> +	unsigned long caddr, chandle;
>  	unsigned long age = jiffies - track->when;
> +	depot_stack_handle_t handle = 0;
>  
> +#ifdef CONFIG_STACKDEPOT
> +	handle = READ_ONCE(track->handle);
> +#endif
>  	start = -1;
>  	end = t->count;
>  
> @@ -5133,7 +5138,8 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
>  			break;
>  
>  		caddr = t->loc[pos].addr;
> -		if (track->addr == caddr) {
> +		chandle = t->loc[pos].handle;
> +		if ((track->addr == caddr) && (handle == chandle)) {
>  
>  			l = &t->loc[pos];
>  			l->count++;
> @@ -5158,6 +5164,8 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
>  
>  		if (track->addr < caddr)
>  			end = pos;
> +		else if (track->addr == caddr && handle < chandle)
> +			end = pos;
>  		else
>  			start = pos;
>  	}

Does this need to properly handle the case where handle == NULL?

> @@ -5180,6 +5188,7 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
>  	l->max_time = age;
>  	l->min_pid = track->pid;
>  	l->max_pid = track->pid;
> +	l->handle = handle;
>  	cpumask_clear(to_cpumask(l->cpus));
>  	cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
>  	nodes_clear(l->nodes);
> @@ -6089,6 +6098,21 @@ static int slab_debugfs_show(struct seq_file *seq, void *v)
>  			seq_printf(seq, " nodes=%*pbl",
>  				 nodemask_pr_args(&l->nodes));
>  
> +#ifdef CONFIG_STACKDEPOT
> +		{
> +			depot_stack_handle_t handle;
> +			unsigned long *entries;
> +			unsigned int nr_entries, j;
> +
> +			handle = READ_ONCE(l->handle);
> +			if (handle) {
> +				nr_entries = stack_depot_fetch(handle, &entries);
> +				seq_puts(seq, "\n");
> +				for (j = 0; j < nr_entries; j++)
> +					seq_printf(seq, "        %pS\n", (void *)entries[j]);
> +			}
> +		}
> +#endif
>  		seq_puts(seq, "\n");
>  	}
>  
> -- 
> 2.35.1
> 
>
Vlastimil Babka April 6, 2022, 9:09 a.m. UTC | #2 
On 4/5/22 23:40, David Rientjes wrote:
>> @@ -5116,9 +5117,13 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
>>  {
>>  	long start, end, pos;
>>  	struct location *l;
>> -	unsigned long caddr;
>> +	unsigned long caddr, chandle;
>>  	unsigned long age = jiffies - track->when;
>> +	depot_stack_handle_t handle = 0;
>>  
>> +#ifdef CONFIG_STACKDEPOT
>> +	handle = READ_ONCE(track->handle);
>> +#endif
>>  	start = -1;
>>  	end = t->count;
>>  
>> @@ -5133,7 +5138,8 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
>>  			break;
>>  
>>  		caddr = t->loc[pos].addr;
>> -		if (track->addr == caddr) {
>> +		chandle = t->loc[pos].handle;
>> +		if ((track->addr == caddr) && (handle == chandle)) {
>>  
>>  			l = &t->loc[pos];
>>  			l->count++;
>> @@ -5158,6 +5164,8 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
>>  
>>  		if (track->addr < caddr)
>>  			end = pos;
>> +		else if (track->addr == caddr && handle < chandle)
>> +			end = pos;
>>  		else
>>  			start = pos;
>>  	}
> 
> Does this need to properly handle the case where handle == NULL?

Hm I can't think of how much more properly is possible. If objects have same
track->addr (which is the immediate caller) and also same NULL handle, they
will be counted together. I think it's the best we can do?
diff mbox series

Patch

diff --git a/mm/slub.c b/mm/slub.c
index 98c1450c23f0..f2e550e1adf0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5064,6 +5064,7 @@  EXPORT_SYMBOL(validate_slab_cache);
  */
 
 struct location {
+	depot_stack_handle_t handle;
 	unsigned long count;
 	unsigned long addr;
 	long long sum_time;
@@ -5116,9 +5117,13 @@  static int add_location(struct loc_track *t, struct kmem_cache *s,
 {
 	long start, end, pos;
 	struct location *l;
-	unsigned long caddr;
+	unsigned long caddr, chandle;
 	unsigned long age = jiffies - track->when;
+	depot_stack_handle_t handle = 0;
 
+#ifdef CONFIG_STACKDEPOT
+	handle = READ_ONCE(track->handle);
+#endif
 	start = -1;
 	end = t->count;
 
@@ -5133,7 +5138,8 @@  static int add_location(struct loc_track *t, struct kmem_cache *s,
 			break;
 
 		caddr = t->loc[pos].addr;
-		if (track->addr == caddr) {
+		chandle = t->loc[pos].handle;
+		if ((track->addr == caddr) && (handle == chandle)) {
 
 			l = &t->loc[pos];
 			l->count++;
@@ -5158,6 +5164,8 @@  static int add_location(struct loc_track *t, struct kmem_cache *s,
 
 		if (track->addr < caddr)
 			end = pos;
+		else if (track->addr == caddr && handle < chandle)
+			end = pos;
 		else
 			start = pos;
 	}
@@ -5180,6 +5188,7 @@  static int add_location(struct loc_track *t, struct kmem_cache *s,
 	l->max_time = age;
 	l->min_pid = track->pid;
 	l->max_pid = track->pid;
+	l->handle = handle;
 	cpumask_clear(to_cpumask(l->cpus));
 	cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
 	nodes_clear(l->nodes);
@@ -6089,6 +6098,21 @@  static int slab_debugfs_show(struct seq_file *seq, void *v)
 			seq_printf(seq, " nodes=%*pbl",
 				 nodemask_pr_args(&l->nodes));
 
+#ifdef CONFIG_STACKDEPOT
+		{
+			depot_stack_handle_t handle;
+			unsigned long *entries;
+			unsigned int nr_entries, j;
+
+			handle = READ_ONCE(l->handle);
+			if (handle) {
+				nr_entries = stack_depot_fetch(handle, &entries);
+				seq_puts(seq, "\n");
+				for (j = 0; j < nr_entries; j++)
+					seq_printf(seq, "        %pS\n", (void *)entries[j]);
+			}
+		}
+#endif
 		seq_puts(seq, "\n");
 	}