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mm/slub: Define struct slab fields for CONFIG_SLUB_CPU_PARTIAL only when enabled

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The fields 'next' and 'slabs' are only used when CONFIG_SLUB_CPU_PARTIAL
is enabled. We can put their definition to #ifdef to prevent accidental
use when disabled.

Currenlty show_slab_objects() and slabs_cpu_partial_show() contain code
accessing the slabs field that's effectively dead with
CONFIG_SLUB_CPU_PARTIAL=n through the wrappers slub_percpu_partial() and
slub_percpu_partial_read_once(), but to prevent a compile error, we need
to hide all this code behind #ifdef.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
This commit is contained in:
Vlastimil Babka 2021-11-10 14:12:45 +01:00
parent 662188c3a2
commit 9c01e9af17
2 changed files with 8 additions and 2 deletions
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2
mm/slab.h
View File

@ -25,10 +25,12 @@ struct slab {
union {
struct list_head slab_list;
struct rcu_head rcu_head;
#ifdef CONFIG_SLUB_CPU_PARTIAL
struct {
struct slab *next;
int slabs; /* Nr of slabs left */
};
#endif
};
struct kmem_cache *slab_cache;
/* Double-word boundary */

8
mm/slub.c
View File

@ -5258,6 +5258,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
total += x;
nodes[node] += x;
#ifdef CONFIG_SLUB_CPU_PARTIAL
slab = slub_percpu_partial_read_once(c);
if (slab) {
node = slab_nid(slab);
@ -5270,6 +5271,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
total += x;
nodes[node] += x;
}
#endif
}
}
@ -5469,9 +5471,10 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
{
int objects = 0;
int slabs = 0;
int cpu;
int cpu __maybe_unused;
int len = 0;
#ifdef CONFIG_SLUB_CPU_PARTIAL
for_each_online_cpu(cpu) {
struct slab *slab;
@ -5480,12 +5483,13 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
if (slab)
slabs += slab->slabs;
}
#endif
/* Approximate half-full slabs, see slub_set_cpu_partial() */
objects = (slabs * oo_objects(s->oo)) / 2;
len += sysfs_emit_at(buf, len, "%d(%d)", objects, slabs);
#ifdef CONFIG_SMP
#if defined(CONFIG_SLUB_CPU_PARTIAL) && defined(CONFIG_SMP)
for_each_online_cpu(cpu) {
struct slab *slab;