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Date: Wed, 26 May 2021 16:05:38 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: glittao@...il.com, cl@...ux.com, penberg@...nel.org,
rientjes@...gle.com, iamjoonsoo.kim@....com,
akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
faiyazm@...eaurora.org
Subject: Re: [RFC 1/3] mm/slub: aggregate objects in cache by stack trace
On 5/21/21 2:11 PM, glittao@...il.com wrote:
> From: Oliver Glitta <glittao@...il.com>
>
> Aggregate objects in slub cache by stack trace in addition to caller
> address during alloc_calls and free_calls implementation
> in debugfs. Add stack trace to output.
Yes, the immediate callers alone often don't tell much.
> Add all_objects implementation to debugfs to print information
> about all objects.
Looks like this sentence applies only to patch 3/3.
> Signed-off-by: Oliver Glitta <glittao@...il.com>
Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
> ---
> Based on next-20210518 and
> https://lore.kernel.org/r/1621341949-26762-1-git-send-email-faiyazm@codeaurora.org/
>
> mm/slub.c | 30 ++++++++++++++++++++++++++++--
> 1 file changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index e9b84eddc50d..d5ed6ed7d68b 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -4770,6 +4770,7 @@ EXPORT_SYMBOL(validate_slab_cache);
> */
>
> struct location {
> + depot_stack_handle_t handle;
> unsigned long count;
> unsigned long addr;
> long long sum_time;
> @@ -4822,9 +4823,15 @@ 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;
>
> +#ifdef CONFIG_STACKDEPOT
> + handle = READ_ONCE(track->handle);
> +#else
> + handle = 0;
> +#endif
> start = -1;
> end = t->count;
>
> @@ -4839,7 +4846,8 @@ 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++;
> @@ -4864,6 +4872,8 @@ 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;
> }
> @@ -4886,6 +4896,7 @@ 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);
> @@ -5837,6 +5848,21 @@ 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, "\t%pS\n", (void *)entries[j]);
> + }
> + }
> +#endif
> seq_puts(seq, "\n");
> }
>
> --
> 2.31.1.272.g89b43f80a5
>
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