[PATCH v2 33/33] mm/slub: Define struct slab fields for CONFIG_SLUB_CPU_PARTIAL only when enabled
From: Vlastimil Babka <hidden>
Date: 2021-12-01 18:32:25
Also in:
linux-patches
Subsystem:
memory management, slab allocator, the rest · Maintainers:
Andrew Morton, Vlastimil Babka, Harry Yoo, Linus Torvalds
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 <redacted> --- mm/slab.h | 2 ++ mm/slub.c | 8 ++++++-- 2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/mm/slab.h b/mm/slab.h
index ee4344a44987..46ea468b29aa 100644
--- a/mm/slab.h
+++ b/mm/slab.h@@ -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 */
diff --git a/mm/slub.c b/mm/slub.c
index 58f0d499a293..978d754d0ada 100644
--- a/mm/slub.c
+++ b/mm/slub.c@@ -5256,6 +5256,7 @@ 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);
@@ -5268,6 +5269,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s, total += x; nodes[node] += x; } +#endif } }
@@ -5467,9 +5469,10 @@ 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;
@@ -5478,12 +5481,13 @@ 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;
--
2.33.1