Re: [PATCH] mm: slub: move sysfs slab alloc/free interfaces to debugfs
From: Faiyaz Mohammed
Date: Tue Apr 06 2021 - 08:28:57 EST
Please ignore this patch!
Thanks and regards,
Mohammed Faiyaz.
On 4/6/2021 5:55 PM, Faiyaz Mohammed wrote:
> alloc_calls and free_calls implementation in sysfs have two issues,
> one is PAGE_SIZE limitiation of sysfs and other is it does not adhere
> to "one value per file" rule.
>
> To overcome this issues, move the alloc_calls and free_calls implemeation
> to debugfs.
>
> Signed-off-by: Faiyaz Mohammed <faiyazm@xxxxxxxxxxxxxx>
> ---
> mm/slub.c | 518 ++++++++++++++++++++++++++++++++++----------------------------
> 1 file changed, 286 insertions(+), 232 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 3021ce9..4d20ee0 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -36,6 +36,7 @@
> #include <linux/memcontrol.h>
> #include <linux/random.h>
>
> +#include <linux/debugfs.h>
> #include <trace/events/kmem.h>
>
> #include "internal.h"
> @@ -225,6 +226,12 @@ static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
> { return 0; }
> #endif
>
> +#ifdef CONFIG_DEBUG_FS
> +static void debugfs_slab_add(struct kmem_cache *);
> +#else
> +static inline void debugfs_slab_add(struct kmem_cache *) { }
> +#endif
> +
> static inline void stat(const struct kmem_cache *s, enum stat_item si)
> {
> #ifdef CONFIG_SLUB_STATS
> @@ -4542,6 +4549,8 @@ int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags)
> if (err)
> __kmem_cache_release(s);
>
> + debugfs_slab_add(s);
> +
> return err;
> }
>
> @@ -4682,221 +4691,6 @@ static long validate_slab_cache(struct kmem_cache *s)
>
> return count;
> }
> -/*
> - * Generate lists of code addresses where slabcache objects are allocated
> - * and freed.
> - */
> -
> -struct location {
> - unsigned long count;
> - unsigned long addr;
> - long long sum_time;
> - long min_time;
> - long max_time;
> - long min_pid;
> - long max_pid;
> - DECLARE_BITMAP(cpus, NR_CPUS);
> - nodemask_t nodes;
> -};
> -
> -struct loc_track {
> - unsigned long max;
> - unsigned long count;
> - struct location *loc;
> -};
> -
> -static void free_loc_track(struct loc_track *t)
> -{
> - if (t->max)
> - free_pages((unsigned long)t->loc,
> - get_order(sizeof(struct location) * t->max));
> -}
> -
> -static int alloc_loc_track(struct loc_track *t, unsigned long max, gfp_t flags)
> -{
> - struct location *l;
> - int order;
> -
> - order = get_order(sizeof(struct location) * max);
> -
> - l = (void *)__get_free_pages(flags, order);
> - if (!l)
> - return 0;
> -
> - if (t->count) {
> - memcpy(l, t->loc, sizeof(struct location) * t->count);
> - free_loc_track(t);
> - }
> - t->max = max;
> - t->loc = l;
> - return 1;
> -}
> -
> -static int add_location(struct loc_track *t, struct kmem_cache *s,
> - const struct track *track)
> -{
> - long start, end, pos;
> - struct location *l;
> - unsigned long caddr;
> - unsigned long age = jiffies - track->when;
> -
> - start = -1;
> - end = t->count;
> -
> - for ( ; ; ) {
> - pos = start + (end - start + 1) / 2;
> -
> - /*
> - * There is nothing at "end". If we end up there
> - * we need to add something to before end.
> - */
> - if (pos == end)
> - break;
> -
> - caddr = t->loc[pos].addr;
> - if (track->addr == caddr) {
> -
> - l = &t->loc[pos];
> - l->count++;
> - if (track->when) {
> - l->sum_time += age;
> - if (age < l->min_time)
> - l->min_time = age;
> - if (age > l->max_time)
> - l->max_time = age;
> -
> - if (track->pid < l->min_pid)
> - l->min_pid = track->pid;
> - if (track->pid > l->max_pid)
> - l->max_pid = track->pid;
> -
> - cpumask_set_cpu(track->cpu,
> - to_cpumask(l->cpus));
> - }
> - node_set(page_to_nid(virt_to_page(track)), l->nodes);
> - return 1;
> - }
> -
> - if (track->addr < caddr)
> - end = pos;
> - else
> - start = pos;
> - }
> -
> - /*
> - * Not found. Insert new tracking element.
> - */
> - if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max, GFP_ATOMIC))
> - return 0;
> -
> - l = t->loc + pos;
> - if (pos < t->count)
> - memmove(l + 1, l,
> - (t->count - pos) * sizeof(struct location));
> - t->count++;
> - l->count = 1;
> - l->addr = track->addr;
> - l->sum_time = age;
> - l->min_time = age;
> - l->max_time = age;
> - l->min_pid = track->pid;
> - l->max_pid = track->pid;
> - cpumask_clear(to_cpumask(l->cpus));
> - cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
> - nodes_clear(l->nodes);
> - node_set(page_to_nid(virt_to_page(track)), l->nodes);
> - return 1;
> -}
> -
> -static void process_slab(struct loc_track *t, struct kmem_cache *s,
> - struct page *page, enum track_item alloc)
> -{
> - void *addr = page_address(page);
> - void *p;
> - unsigned long *map;
> -
> - map = get_map(s, page);
> - for_each_object(p, s, addr, page->objects)
> - if (!test_bit(__obj_to_index(s, addr, p), map))
> - add_location(t, s, get_track(s, p, alloc));
> - put_map(map);
> -}
> -
> -static int list_locations(struct kmem_cache *s, char *buf,
> - enum track_item alloc)
> -{
> - int len = 0;
> - unsigned long i;
> - struct loc_track t = { 0, 0, NULL };
> - int node;
> - struct kmem_cache_node *n;
> -
> - if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
> - GFP_KERNEL)) {
> - return sysfs_emit(buf, "Out of memory\n");
> - }
> - /* Push back cpu slabs */
> - flush_all(s);
> -
> - for_each_kmem_cache_node(s, node, n) {
> - unsigned long flags;
> - struct page *page;
> -
> - if (!atomic_long_read(&n->nr_slabs))
> - continue;
> -
> - spin_lock_irqsave(&n->list_lock, flags);
> - list_for_each_entry(page, &n->partial, slab_list)
> - process_slab(&t, s, page, alloc);
> - list_for_each_entry(page, &n->full, slab_list)
> - process_slab(&t, s, page, alloc);
> - spin_unlock_irqrestore(&n->list_lock, flags);
> - }
> -
> - for (i = 0; i < t.count; i++) {
> - struct location *l = &t.loc[i];
> -
> - len += sysfs_emit_at(buf, len, "%7ld ", l->count);
> -
> - if (l->addr)
> - len += sysfs_emit_at(buf, len, "%pS", (void *)l->addr);
> - else
> - len += sysfs_emit_at(buf, len, "<not-available>");
> -
> - if (l->sum_time != l->min_time)
> - len += sysfs_emit_at(buf, 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);
> -
> - if (l->min_pid != l->max_pid)
> - len += sysfs_emit_at(buf, len, " pid=%ld-%ld",
> - l->min_pid, l->max_pid);
> - else
> - len += sysfs_emit_at(buf, 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",
> - cpumask_pr_args(to_cpumask(l->cpus)));
> -
> - if (nr_online_nodes > 1 && !nodes_empty(l->nodes))
> - len += sysfs_emit_at(buf, len, " nodes=%*pbl",
> - nodemask_pr_args(&l->nodes));
> -
> - len += sysfs_emit_at(buf, len, "\n");
> - }
> -
> - free_loc_track(&t);
> - if (!t.count)
> - len += sysfs_emit_at(buf, len, "No data\n");
> -
> - return len;
> -}
> #endif /* CONFIG_SLUB_DEBUG */
>
> #ifdef SLUB_RESILIENCY_TEST
> @@ -5346,21 +5140,6 @@ static ssize_t validate_store(struct kmem_cache *s,
> }
> SLAB_ATTR(validate);
>
> -static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf)
> -{
> - if (!(s->flags & SLAB_STORE_USER))
> - return -ENOSYS;
> - return list_locations(s, buf, TRACK_ALLOC);
> -}
> -SLAB_ATTR_RO(alloc_calls);
> -
> -static ssize_t free_calls_show(struct kmem_cache *s, char *buf)
> -{
> - if (!(s->flags & SLAB_STORE_USER))
> - return -ENOSYS;
> - return list_locations(s, buf, TRACK_FREE);
> -}
> -SLAB_ATTR_RO(free_calls);
> #endif /* CONFIG_SLUB_DEBUG */
>
> #ifdef CONFIG_FAILSLAB
> @@ -5524,8 +5303,6 @@ 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,
> @@ -5814,6 +5591,283 @@ static int __init slab_sysfs_init(void)
> __initcall(slab_sysfs_init);
> #endif /* CONFIG_SYSFS */
>
> +#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_SLUB_DEBUG)
> +/*
> + * Generate lists of code addresses where slabcache objects are allocated
> + * and freed.
> + */
> +
> +struct location {
> + unsigned long count;
> + unsigned long addr;
> + long long sum_time;
> + long min_time;
> + long max_time;
> + long min_pid;
> + long max_pid;
> + DECLARE_BITMAP(cpus, NR_CPUS);
> + nodemask_t nodes;
> +};
> +
> +struct loc_track {
> + unsigned long max;
> + unsigned long count;
> + struct location *loc;
> +};
> +
> +static struct dentry *slab_debugfs_root;
> +
> +static struct dentry *slab_debugfs_cache;
> +
> +static void free_loc_track(struct loc_track *t)
> +{
> + if (t->max)
> + free_pages((unsigned long)t->loc,
> + get_order(sizeof(struct location) * t->max));
> +}
> +
> +static int alloc_loc_track(struct loc_track *t, unsigned long max, gfp_t flags)
> +{
> + struct location *l;
> + int order;
> +
> + order = get_order(sizeof(struct location) * max);
> +
> + l = (void *)__get_free_pages(flags, order);
> + if (!l)
> + return 0;
> +
> + if (t->count) {
> + memcpy(l, t->loc, sizeof(struct location) * t->count);
> + free_loc_track(t);
> + }
> + t->max = max;
> + t->loc = l;
> + return 1;
> +}
> +
> +static int add_location(struct loc_track *t, struct kmem_cache *s,
> + const struct track *track)
> +{
> + long start, end, pos;
> + struct location *l;
> + unsigned long caddr;
> + unsigned long age = jiffies - track->when;
> +
> + start = -1;
> + end = t->count;
> +
> + for ( ; ; ) {
> + pos = start + (end - start + 1) / 2;
> +
> + /*
> + * There is nothing at "end". If we end up there
> + * we need to add something to before end.
> + */
> + if (pos == end)
> + break;
> +
> + caddr = t->loc[pos].addr;
> + if (track->addr == caddr) {
> +
> + l = &t->loc[pos];
> + l->count++;
> + if (track->when) {
> + l->sum_time += age;
> + if (age < l->min_time)
> + l->min_time = age;
> + if (age > l->max_time)
> + l->max_time = age;
> +
> + if (track->pid < l->min_pid)
> + l->min_pid = track->pid;
> + if (track->pid > l->max_pid)
> + l->max_pid = track->pid;
> +
> + cpumask_set_cpu(track->cpu,
> + to_cpumask(l->cpus));
> + }
> + node_set(page_to_nid(virt_to_page(track)), l->nodes);
> + return 1;
> + }
> +
> + if (track->addr < caddr)
> + end = pos;
> + else
> + start = pos;
> + }
> +
> + /*
> + * Not found. Insert new tracking element.
> + */
> + if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max, GFP_ATOMIC))
> + return 0;
> +
> + l = t->loc + pos;
> + if (pos < t->count)
> + memmove(l + 1, l,
> + (t->count - pos) * sizeof(struct location));
> + t->count++;
> + l->count = 1;
> + l->addr = track->addr;
> + l->sum_time = age;
> + l->min_time = age;
> + l->max_time = age;
> + l->min_pid = track->pid;
> + l->max_pid = track->pid;
> + cpumask_clear(to_cpumask(l->cpus));
> + cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
> + nodes_clear(l->nodes);
> + node_set(page_to_nid(virt_to_page(track)), l->nodes);
> + return 1;
> +}
> +
> +static void process_slab(struct loc_track *t, struct kmem_cache *s,
> + struct page *page, enum track_item alloc)
> +{
> + void *addr = page_address(page);
> + void *p;
> + unsigned long *map;
> +
> + map = get_map(s, page);
> + for_each_object(p, s, addr, page->objects)
> + if (!test_bit(__obj_to_index(s, addr, p), map))
> + add_location(t, s, get_track(s, p, alloc));
> + put_map(map);
> +}
> +
> +static int list_locations(struct seq_file *seq, struct kmem_cache *s,
> + enum track_item alloc)
> +{
> + unsigned long i;
> + struct loc_track t = { 0, 0, NULL };
> + int node;
> + struct kmem_cache_node *n;
> +
> + if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
> + GFP_KERNEL)) {
> + seq_puts(seq, "Out of memory\n");
> + return -ENOMEM;
> + }
> + /* Push back cpu slabs */
> + flush_all(s);
> +
> + for_each_kmem_cache_node(s, node, n) {
> + unsigned long flags;
> + struct page *page;
> +
> + if (!atomic_long_read(&n->nr_slabs))
> + continue;
> +
> + spin_lock_irqsave(&n->list_lock, flags);
> + list_for_each_entry(page, &n->partial, slab_list)
> + process_slab(&t, s, page, alloc);
> + list_for_each_entry(page, &n->full, slab_list)
> + process_slab(&t, s, page, alloc);
> + spin_unlock_irqrestore(&n->list_lock, flags);
> + }
> +
> + for (i = 0; i < t.count; i++) {
> + struct location *l = &t.loc[i];
> +
> + seq_printf(seq, "%7ld ", l->count);
> +
> + if (l->addr)
> + seq_printf(seq, "%pS", (void *)l->addr);
> + else
> + seq_puts(seq, "<not-available>");
> +
> + if (l->sum_time != l->min_time) {
> + seq_printf(seq, " age=%ld/%ld/%ld",
> + l->min_time,
> + (long)div_u64(l->sum_time, l->count),
> + l->max_time);
> + } else
> + seq_printf(seq, " age=%ld",
> + l->min_time);
> +
> + if (l->min_pid != l->max_pid)
> + seq_printf(seq, " pid=%ld-%ld",
> + l->min_pid, l->max_pid);
> + else
> + seq_printf(seq, " pid=%ld",
> + l->min_pid);
> +
> + if (num_online_cpus() > 1 &&
> + !cpumask_empty(to_cpumask(l->cpus)))
> + seq_printf(seq, " cpus=%*pbl",
> + cpumask_pr_args(to_cpumask(l->cpus)));
> +
> + if (nr_online_nodes > 1 && !nodes_empty(l->nodes))
> + seq_printf(seq, " nodes=%*pbl",
> + nodemask_pr_args(&l->nodes));
> +
> + seq_puts(seq, "\n");
> + }
> +
> + free_loc_track(&t);
> + if (!t.count)
> + seq_puts(seq, "No data\n");
> + return 0;
> +}
> +
> +static int slab_debug_trace(struct seq_file *seq, void *ignored)
> +{
> + struct kmem_cache *s = seq->private;
> +
> + if (!(s->flags & SLAB_STORE_USER))
> + return 0;
> +
> + if (strcmp(seq->file->f_path.dentry->d_name.name, "alloc_trace") == 0)
> + return list_locations(seq, s, TRACK_ALLOC);
> + else
> + return list_locations(seq, s, TRACK_FREE);
> +
> + return 0;
> +}
> +
> +static int slab_debug_trace_open(struct inode *inode, struct file *filp)
> +{
> + return single_open(filp, slab_debug_trace,
> + file_inode(filp)->i_private);
> +}
> +
> +static const struct file_operations slab_debug_fops = {
> + .open = slab_debug_trace_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> +};
> +
> +static void debugfs_slab_add(struct kmem_cache *s)
> +{
> + if (unlikely(!slab_debugfs_root))
> + return;
> +
> + slab_debugfs_cache = debugfs_create_dir(s->name, slab_debugfs_root);
> + if (!IS_ERR(slab_debugfs_cache)) {
> + debugfs_create_file("alloc_trace", 0400,
> + slab_debugfs_cache, s, &slab_debug_fops);
> +
> + debugfs_create_file("free_trace", 0400,
> + slab_debugfs_cache, s, &slab_debug_fops);
> + }
> +}
> +
> +static void __init slab_debugfs_init(void)
> +{
> + struct kmem_cache *s;
> +
> + slab_debugfs_root = debugfs_create_dir("slab", NULL);
> + if (!IS_ERR(slab_debugfs_root))
> + list_for_each_entry(s, &slab_caches, list)
> + debugfs_slab_add(s);
> + else
> + pr_err("Cannot create slab debugfs.\n");
> +
> +}
> +__initcall(slab_debugfs_init);
> +#endif
> /*
> * The /proc/slabinfo ABI
> */
>