2022-11-21 17:21:57

by Vlastimil Babka

Subject: [PATCH 03/12] mm, slub: disable SYSFS support with CONFIG_SLUB_TINY

Currently SLUB enables its sysfs support depending unconditionally on
the general CONFIG_SYSFS setting. To reduce the configuration
combination space, make CONFIG_SLUB_TINY disable SLUB's sysfs support by
reusing the existing SLAB_SUPPORTS_SYSFS define. It is unlikely that
real tiny systems would combine CONFIG_SLUB_TINY with CONFIG_SYSFS, but
a randconfig might.

Signed-off-by: Vlastimil Babka <[email protected]>
---
include/linux/slub_def.h | 2 +-
mm/slub.c | 12 ++++++------
2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index f9c68a9dac04..c186f25c8148 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -142,7 +142,7 @@ struct kmem_cache {
struct kmem_cache_node *node[MAX_NUMNODES];
};

-#ifdef CONFIG_SYSFS
+#if defined(CONFIG_SYSFS) && !defined(CONFIG_SLUB_TINY)
#define SLAB_SUPPORTS_SYSFS
void sysfs_slab_unlink(struct kmem_cache *);
void sysfs_slab_release(struct kmem_cache *);
diff --git a/mm/slub.c b/mm/slub.c
index 157527d7101b..ab085aa2f1f0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -298,7 +298,7 @@ struct track {

enum track_item { TRACK_ALLOC, TRACK_FREE };

-#ifdef CONFIG_SYSFS
+#ifdef SLAB_SUPPORTS_SYSFS
static int sysfs_slab_add(struct kmem_cache *);
static int sysfs_slab_alias(struct kmem_cache *, const char *);
#else
@@ -2935,7 +2935,7 @@ static noinline void free_debug_processing(
}
#endif /* CONFIG_SLUB_DEBUG */

-#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
+#if defined(CONFIG_SLUB_DEBUG) || defined(SLAB_SUPPORTS_SYSFS)
static unsigned long count_partial(struct kmem_cache_node *n,
int (*get_count)(struct slab *))
{
@@ -2949,7 +2949,7 @@ static unsigned long count_partial(struct kmem_cache_node *n,
spin_unlock_irqrestore(&n->list_lock, flags);
return x;
}
-#endif /* CONFIG_SLUB_DEBUG || CONFIG_SYSFS */
+#endif /* CONFIG_SLUB_DEBUG || SLAB_SUPPORTS_SYSFS */

static noinline void
slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
@@ -4924,7 +4924,7 @@ int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags)
return 0;
}

-#ifdef CONFIG_SYSFS
+#ifdef SLAB_SUPPORTS_SYSFS
static int count_inuse(struct slab *slab)
{
return slab->inuse;
@@ -5182,7 +5182,7 @@ static void process_slab(struct loc_track *t, struct kmem_cache *s,
#endif /* CONFIG_DEBUG_FS */
#endif /* CONFIG_SLUB_DEBUG */

-#ifdef CONFIG_SYSFS
+#ifdef SLAB_SUPPORTS_SYSFS
enum slab_stat_type {
SL_ALL, /* All slabs */
SL_PARTIAL, /* Only partially allocated slabs */
@@ -6056,7 +6056,7 @@ static int __init slab_sysfs_init(void)
}

__initcall(slab_sysfs_init);
-#endif /* CONFIG_SYSFS */
+#endif /* SLAB_SUPPORTS_SYSFS */

#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_DEBUG_FS)
static int slab_debugfs_show(struct seq_file *seq, void *v)
--
2.38.1

2022-11-24 01:59:38

by Roman Gushchin

Subject: Re: [PATCH 03/12] mm, slub: disable SYSFS support with CONFIG_SLUB_TINY

On Mon, Nov 21, 2022 at 06:11:53PM +0100, Vlastimil Babka wrote:
> Currently SLUB enables its sysfs support depending unconditionally on
> the general CONFIG_SYSFS setting. To reduce the configuration
> combination space, make CONFIG_SLUB_TINY disable SLUB's sysfs support by
> reusing the existing SLAB_SUPPORTS_SYSFS define. It is unlikely that
> real tiny systems would combine CONFIG_SLUB_TINY with CONFIG_SYSFS, but
> a randconfig might.

Hm, don't we want to introduce CONFIG_SLAB_SYSFS instead?
I believe many users don't really need it, even if they don't
need CONFIG_SLUB_TINY and they do have CONFIG_SYSFS.

Thanks!

2022-11-24 10:13:32

by Vlastimil Babka

Subject: Re: [PATCH 03/12] mm, slub: disable SYSFS support with CONFIG_SLUB_TINY

On 11/24/22 02:12, Roman Gushchin wrote:
> On Mon, Nov 21, 2022 at 06:11:53PM +0100, Vlastimil Babka wrote:
>> Currently SLUB enables its sysfs support depending unconditionally on
>> the general CONFIG_SYSFS setting. To reduce the configuration
>> combination space, make CONFIG_SLUB_TINY disable SLUB's sysfs support by
>> reusing the existing SLAB_SUPPORTS_SYSFS define. It is unlikely that
>> real tiny systems would combine CONFIG_SLUB_TINY with CONFIG_SYSFS, but
>> a randconfig might.
>
> Hm, don't we want to introduce CONFIG_SLAB_SYSFS instead?
> I believe many users don't really need it, even if they don't
> need CONFIG_SLUB_TINY and they do have CONFIG_SYSFS.

Dunno, adding more and more config options is generally frowned upon. Also
tools might be using it to get more details than /proc/slabinfo does - i.e.
tools/vm/slabinfo.c

> Thanks!