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Date: Wed, 17 Feb 2021 17:08:57 +0530
From: Faiyaz Mohammed <faiyazm@...eaurora.org>
To: cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
iamjoonsoo.kim@....com, akpm@...ux-foundation.org, vbabka@...e.cz,
willy@...radead.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Cc: vinmenon@...eaurora.org
Subject: Re: [PATCH v2] mm: slub: Convert sys slab alloc_calls, free_calls to
bin attribute
+linux-mm, linux-kernel.
On 2/17/2021 12:01 PM, Faiyaz Mohammed wrote:
> Reading the sys slab alloc_calls, free_calls returns the available object
> owners, but the size of this file is limited to PAGE_SIZE
> because of the limitation of sysfs attributes, it is returning the
> partial owner info, which is not sufficient to debug/account the slab
> memory and alloc_calls output is not matching with /proc/slabinfo.
>
> To remove the PAGE_SIZE limitation converted the sys slab
> alloc_calls, free_calls to bin attribute.
>
> Signed-off-by: Faiyaz Mohammed <faiyazm@...eaurora.org>
> ---
> mm/slub.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 63 insertions(+), 21 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index b22a4b1..71cfe3b 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -37,6 +37,9 @@
>
> #include <trace/events/kmem.h>
>
> +#define TRACE_ENTRY_MAX 80
> +#define TRACKS_PER_PAGE ((PAGE_SIZE - KSYM_SYMBOL_LEN - 100) / TRACE_ENTRY_MAX)
> +
> #include "internal.h"
>
> /*
> @@ -4748,6 +4751,7 @@ static int list_locations(struct kmem_cache *s, char *buf,
> struct loc_track t = { 0, 0, NULL };
> int node;
> struct kmem_cache_node *n;
> + unsigned int previous_read_count = 0;
>
> if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
> GFP_KERNEL)) {
> @@ -4756,6 +4760,11 @@ static int list_locations(struct kmem_cache *s, char *buf,
> /* Push back cpu slabs */
> flush_all(s);
>
> + if (offset != 0)
> + previous_read_count = (offset / TRACE_ENTRY_MAX);
> +
> + memset(buf, 0, PAGE_SIZE);
> +
> for_each_kmem_cache_node(s, node, n) {
> unsigned long flags;
> struct page *page;
> @@ -4771,48 +4780,62 @@ static int list_locations(struct kmem_cache *s, char *buf,
> spin_unlock_irqrestore(&n->list_lock, flags);
> }
>
> - for (i = 0; i < t.count; i++) {
> + for (i = previous_read_count; i < t.count; i++) {
> struct location *l = &t.loc[i];
> + unsigned int cur_len = 0;
>
> - len += sysfs_emit_at(buf, len, "%7ld ", l->count);
> + cur_len += sysfs_emit_at(buf, cur_len + len, "%7ld ", l->count);
>
> if (l->addr)
> - len += sysfs_emit_at(buf, len, "%pS", (void *)l->addr);
> + cur_len += sysfs_emit_at(buf, cur_len + len, "%pS", (void *)l->addr);
> else
> - len += sysfs_emit_at(buf, len, "<not-available>");
> + cur_len += sysfs_emit_at(buf, cur_len + len, "<not-available>");
>
> if (l->sum_time != l->min_time)
> - len += sysfs_emit_at(buf, len, " age=%ld/%ld/%ld",
> + cur_len += sysfs_emit_at(buf, cur_len + len, " age=%ld/%ld/%ld",
> l->min_time,
> (long)div_u64(l->sum_time,
> l->count),
> l->max_time);
> else
> - len += sysfs_emit_at(buf, len, " age=%ld", l->min_time);
> + cur_len += sysfs_emit_at(buf, cur_len + len, " age=%ld", l->min_time);
>
> if (l->min_pid != l->max_pid)
> - len += sysfs_emit_at(buf, len, " pid=%ld-%ld",
> + cur_len += sysfs_emit_at(buf, cur_len + len, " pid=%ld-%ld",
> l->min_pid, l->max_pid);
> else
> - len += sysfs_emit_at(buf, len, " pid=%ld",
> + cur_len += sysfs_emit_at(buf, cur_len + len, " pid=%ld",
> l->min_pid);
>
> if (num_online_cpus() > 1 &&
> !cpumask_empty(to_cpumask(l->cpus)))
> - len += sysfs_emit_at(buf, len, " cpus=%*pbl",
> + cur_len += sysfs_emit_at(buf, cur_len + len, " cpus=%*pbl",
> cpumask_pr_args(to_cpumask(l->cpus)));
>
> if (nr_online_nodes > 1 && !nodes_empty(l->nodes))
> - len += sysfs_emit_at(buf, len, " nodes=%*pbl",
> + cur_len += sysfs_emit_at(buf, cur_len + len, " nodes=%*pbl",
> nodemask_pr_args(&l->nodes));
>
> + if (cur_len >= TRACE_ENTRY_MAX)
> + cur_len -= (cur_len % TRACE_ENTRY_MAX) - 1;
> + else if (cur_len < TRACE_ENTRY_MAX)
> + cur_len += TRACE_ENTRY_MAX - (cur_len % TRACE_ENTRY_MAX) - 1;
> +
> + len += cur_len;
> +
> len += sysfs_emit_at(buf, len, "\n");
> +
> + if (i >= (previous_read_count + TRACKS_PER_PAGE))
> + break;
> +
> }
>
> - free_loc_track(&t);
> - if (!t.count)
> - len += sysfs_emit_at(buf, len, "No data\n");
> + if (((previous_read_count > t.count) | (i >= t.count)) && (offset != 0))
> + len = 0;
> + else if (!t.count)
> + len += sprintf(buf, "No data\n");
>
> + free_loc_track(&t);
> return len;
> }
> #endif /* CONFIG_SLUB_DEBUG */
> @@ -5280,21 +5303,33 @@ static ssize_t validate_store(struct kmem_cache *s,
> }
> SLAB_ATTR(validate);
>
> -static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf)
> +static ssize_t alloc_calls_read(struct file *filp, struct kobject *kobj,
> + struct bin_attribute *bin_attr, char *buf,
> + loff_t offset, size_t count)
> {
> + struct kmem_cache *s;
> +
> + s = to_slab(kobj);
> if (!(s->flags & SLAB_STORE_USER))
> return -ENOSYS;
> - return list_locations(s, buf, TRACK_ALLOC);
> +
> + return list_locations(s, buf, offset, TRACK_ALLOC);
> }
> -SLAB_ATTR_RO(alloc_calls);
> +BIN_ATTR_RO(alloc_calls, 0);
>
> -static ssize_t free_calls_show(struct kmem_cache *s, char *buf)
> +static ssize_t free_calls_read(struct file *filp, struct kobject *kobj,
> + struct bin_attribute *bin_attr, char *buf,
> + loff_t offset, size_t count)
> {
> + struct kmem_cache *s;
> +
> + s = to_slab(kobj);
> if (!(s->flags & SLAB_STORE_USER))
> return -ENOSYS;
> - return list_locations(s, buf, TRACK_FREE);
> +
> + return list_locations(s, buf, offset, TRACK_FREE);
> }
> -SLAB_ATTR_RO(free_calls);
> +BIN_ATTR_RO(free_calls, 0);
> #endif /* CONFIG_SLUB_DEBUG */
>
> #ifdef CONFIG_FAILSLAB
> @@ -5430,6 +5465,14 @@ STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);
> STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);
> #endif /* CONFIG_SLUB_STATS */
>
> +
> +static struct bin_attribute *slab_bin_attrs[] = {
> +#ifdef CONFIG_SLUB_DEBUG
> + &bin_attr_alloc_calls,
> + &bin_attr_free_calls,
> +#endif
> +};
> +
> static struct attribute *slab_attrs[] = {
> &slab_size_attr.attr,
> &object_size_attr.attr,
> @@ -5458,8 +5501,6 @@ static struct attribute *slab_attrs[] = {
> &poison_attr.attr,
> &store_user_attr.attr,
> &validate_attr.attr,
> - &alloc_calls_attr.attr,
> - &free_calls_attr.attr,
> #endif
> #ifdef CONFIG_ZONE_DMA
> &cache_dma_attr.attr,
> @@ -5505,6 +5546,7 @@ static struct attribute *slab_attrs[] = {
>
> static const struct attribute_group slab_attr_group = {
> .attrs = slab_attrs,
> + .bin_attrs = slab_bin_attrs,
> };
>
> static ssize_t slab_attr_show(struct kobject *kobj,
>
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