slub: add ability to list alloc / free callers per slab
This patch enables listing the callers who allocated or freed objects in a
cache.
For example to list the allocators for kmalloc-128 do
cat /sys/slab/kmalloc-128/alloc_calls
7 sn_io_slot_fixup+0x40/0x700
7 sn_io_slot_fixup+0x80/0x700
9 sn_bus_fixup+0xe0/0x380
6 param_sysfs_setup+0xf0/0x280
276 percpu_populate+0xf0/0x1a0
19 __register_chrdev_region+0x30/0x360
8 expand_files+0x2e0/0x6e0
1 sys_epoll_create+0x60/0x200
1 __mounts_open+0x140/0x2c0
65 kmem_alloc+0x110/0x280
3 alloc_disk_node+0xe0/0x200
33 as_get_io_context+0x90/0x280
74 kobject_kset_add_dir+0x40/0x140
12 pci_create_bus+0x2a0/0x5c0
1 acpi_ev_create_gpe_block+0x120/0x9e0
41 con_insert_unipair+0x100/0x1c0
1 uart_open+0x1c0/0xba0
1 dma_pool_create+0xe0/0x340
2 neigh_table_init_no_netlink+0x260/0x4c0
6 neigh_parms_alloc+0x30/0x200
1 netlink_kernel_create+0x130/0x320
5 fz_hash_alloc+0x50/0xe0
2 sn_common_hubdev_init+0xd0/0x6e0
28 kernel_param_sysfs_setup+0x30/0x180
72 process_zones+0x70/0x2e0
cat /sys/slab/kmalloc-128/free_calls
558 <not-available>
3 sn_io_slot_fixup+0x600/0x700
84 free_fdtable_rcu+0x120/0x260
2 seq_release+0x40/0x60
6 kmem_free+0x70/0xc0
24 free_as_io_context+0x20/0x200
1 acpi_get_object_info+0x3a0/0x3e0
1 acpi_add_single_object+0xcf0/0x1e40
2 con_release_unimap+0x80/0x140
1 free+0x20/0x40
SLAB_STORE_USER must be enabled for a slab cache by either booting with
"slab_debug" or enabling user tracking specifically for the slab of interest.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Lameter
Linus Torvalds
parent
e95eed571e
commit
88a420e4e2
184
mm/slub.c
184
mm/slub.c
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@ -97,9 +97,6 @@
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*
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* - Support PAGE_ALLOC_DEBUG. Should be easy to do.
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*
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* - Support DEBUG_SLAB_LEAK. Trouble is we do not know where the full
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* slabs are in SLUB.
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*
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* - SLAB_DEBUG_INITIAL is not supported but I have never seen a use of
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* it.
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*
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@ -2659,6 +2656,169 @@ static unsigned long validate_slab_cache(struct kmem_cache *s)
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return count;
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}
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/*
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* Generate lists of locations where slabcache objects are allocated
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* and freed.
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*/
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struct location {
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unsigned long count;
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void *addr;
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};
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struct loc_track {
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unsigned long max;
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unsigned long count;
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struct location *loc;
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};
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static void free_loc_track(struct loc_track *t)
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{
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if (t->max)
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free_pages((unsigned long)t->loc,
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get_order(sizeof(struct location) * t->max));
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}
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static int alloc_loc_track(struct loc_track *t, unsigned long max)
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{
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struct location *l;
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int order;
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if (!max)
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max = PAGE_SIZE / sizeof(struct location);
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order = get_order(sizeof(struct location) * max);
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l = (void *)__get_free_pages(GFP_KERNEL, order);
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if (!l)
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return 0;
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if (t->count) {
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memcpy(l, t->loc, sizeof(struct location) * t->count);
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free_loc_track(t);
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}
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t->max = max;
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t->loc = l;
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return 1;
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}
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static int add_location(struct loc_track *t, struct kmem_cache *s,
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void *addr)
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{
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long start, end, pos;
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struct location *l;
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void *caddr;
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start = -1;
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end = t->count;
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for ( ; ; ) {
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pos = start + (end - start + 1) / 2;
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/*
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* There is nothing at "end". If we end up there
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* we need to add something to before end.
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*/
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if (pos == end)
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break;
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caddr = t->loc[pos].addr;
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if (addr == caddr) {
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t->loc[pos].count++;
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return 1;
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}
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if (addr < caddr)
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end = pos;
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else
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start = pos;
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}
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/*
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* Not found. Insert new tracking element
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*/
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if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max))
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return 0;
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l = t->loc + pos;
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if (pos < t->count)
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memmove(l + 1, l,
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(t->count - pos) * sizeof(struct location));
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t->count++;
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l->count = 1;
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l->addr = addr;
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return 1;
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}
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static void process_slab(struct loc_track *t, struct kmem_cache *s,
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struct page *page, enum track_item alloc)
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{
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void *addr = page_address(page);
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unsigned long map[BITS_TO_LONGS(s->objects)];
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void *p;
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bitmap_zero(map, s->objects);
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for (p = page->freelist; p; p = get_freepointer(s, p))
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set_bit((p - addr) / s->size, map);
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for (p = addr; p < addr + s->objects * s->size; p += s->size)
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if (!test_bit((p - addr) / s->size, map)) {
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void *addr = get_track(s, p, alloc)->addr;
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add_location(t, s, addr);
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}
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}
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static int list_locations(struct kmem_cache *s, char *buf,
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enum track_item alloc)
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{
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int n = 0;
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unsigned long i;
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struct loc_track t;
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int node;
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t.count = 0;
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t.max = 0;
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/* Push back cpu slabs */
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flush_all(s);
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for_each_online_node(node) {
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struct kmem_cache_node *n = get_node(s, node);
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unsigned long flags;
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struct page *page;
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if (!atomic_read(&n->nr_slabs))
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continue;
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spin_lock_irqsave(&n->list_lock, flags);
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list_for_each_entry(page, &n->partial, lru)
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process_slab(&t, s, page, alloc);
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list_for_each_entry(page, &n->full, lru)
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process_slab(&t, s, page, alloc);
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spin_unlock_irqrestore(&n->list_lock, flags);
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}
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for (i = 0; i < t.count; i++) {
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void *addr = t.loc[i].addr;
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if (n > PAGE_SIZE - 100)
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break;
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n += sprintf(buf + n, "%7ld ", t.loc[i].count);
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if (addr)
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n += sprint_symbol(buf + n, (unsigned long)t.loc[i].addr);
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else
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n += sprintf(buf + n, "<not-available>");
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n += sprintf(buf + n, "\n");
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}
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free_loc_track(&t);
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if (!t.count)
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n += sprintf(buf, "No data\n");
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return n;
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}
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static unsigned long count_partial(struct kmem_cache_node *n)
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{
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unsigned long flags;
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@ -3009,6 +3169,22 @@ static ssize_t validate_store(struct kmem_cache *s,
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}
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SLAB_ATTR(validate);
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static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf)
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{
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if (!(s->flags & SLAB_STORE_USER))
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return -ENOSYS;
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return list_locations(s, buf, TRACK_ALLOC);
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}
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SLAB_ATTR_RO(alloc_calls);
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static ssize_t free_calls_show(struct kmem_cache *s, char *buf)
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{
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if (!(s->flags & SLAB_STORE_USER))
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return -ENOSYS;
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return list_locations(s, buf, TRACK_FREE);
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}
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SLAB_ATTR_RO(free_calls);
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#ifdef CONFIG_NUMA
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static ssize_t defrag_ratio_show(struct kmem_cache *s, char *buf)
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{
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@ -3049,6 +3225,8 @@ static struct attribute * slab_attrs[] = {
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&poison_attr.attr,
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&store_user_attr.attr,
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&validate_attr.attr,
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&alloc_calls_attr.attr,
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&free_calls_attr.attr,
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#ifdef CONFIG_ZONE_DMA
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&cache_dma_attr.attr,
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#endif
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