On Mon, 4 Apr 2022, Vlastimil Babka wrote:
> From: Oliver Glitta <glittao@xxxxxxxxx>
>
> 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@xxxxxxxxx>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> Reviewed-and-tested-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
> ---
> 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
>
>
