mm/slub: limit number of node partial slabs only in cache creation

SLUB sets number of minimum partial slabs for node (min_partial)
using set_min_partial(). SLUB holds at least min_partial slabs even if
they're empty to avoid excessive use of page allocator.

set_min_partial() limits value of min_partial limits value of
min_partial MIN_PARTIAL and MAX_PARTIAL. As set_min_partial() can be
called by min_partial_store() too, Only limit value of min_partial
in kmem_cache_open() so that it can be changed to value that a user wants.

[ rientjes@google.com: Fold set_min_partial() into its callers ]

Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Link: https://lore.kernel.org/r/20220307074057.902222-2-42.hyeyoo@gmail.com

diff --git a/mm/slub.c b/mm/slub.c
index 261474092e43e48eaa1fc1a1809b98485e2d87d9..1ce09b0347ad5bfb99c0f500b2ff45578384c387 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4000,15 +4000,6 @@ static int init_kmem_cache_nodes(struct kmem_cache *s)
        return 1;
 }
 
-static void set_min_partial(struct kmem_cache *s, unsigned long min)
-{
-       if (min < MIN_PARTIAL)
-               min = MIN_PARTIAL;
-       else if (min > MAX_PARTIAL)
-               min = MAX_PARTIAL;
-       s->min_partial = min;
-}
-
 static void set_cpu_partial(struct kmem_cache *s)
 {
 #ifdef CONFIG_SLUB_CPU_PARTIAL
@@ -4215,7 +4206,8 @@ static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
         * The larger the object size is, the more slabs we want on the partial
         * list to avoid pounding the page allocator excessively.
         */
-       set_min_partial(s, ilog2(s->size) / 2);
+       s->min_partial = min_t(unsigned long, MAX_PARTIAL, ilog2(s->size) / 2);
+       s->min_partial = max_t(unsigned long, MIN_PARTIAL, s->min_partial);
 
        set_cpu_partial(s);
 
@@ -5396,7 +5388,7 @@ static ssize_t min_partial_store(struct kmem_cache *s, const char *buf,
        if (err)
                return err;
 
-       set_min_partial(s, min);
+       s->min_partial = min;
        return length;
 }
 SLAB_ATTR(min_partial);