Commit 33647783 authored by Ohhoon Kwon's avatar Ohhoon Kwon Committed by Vlastimil Babka
Browse files

mm/slab_common: move dma-kmalloc caches creation into new_kmalloc_cache() 



There are four types of kmalloc_caches: KMALLOC_NORMAL, KMALLOC_CGROUP,
KMALLOC_RECLAIM, and KMALLOC_DMA. While the first three types are
created using new_kmalloc_cache(), KMALLOC_DMA caches are created in a
separate logic. Let KMALLOC_DMA caches be also created using
new_kmalloc_cache(), to enhance readability.

Historically, there were only KMALLOC_NORMAL caches and KMALLOC_DMA
caches in the first place, and they were initialized in two separate
logics. However, when KMALLOC_RECLAIM was introduced in v4.20 via
commit 1291523f ("mm, slab/slub: introduce kmalloc-reclaimable
caches") and KMALLOC_CGROUP was introduced in v5.14 via
commit 494c1dfe ("mm: memcg/slab: create a new set of kmalloc-cg-<n>
caches"), their creations were merged with KMALLOC_NORMAL's only.
KMALLOC_DMA creation logic should be merged with them, too.

By merging KMALLOC_DMA initialization with other types, the following
two changes might occur:
1. The order dma-kmalloc-<n> caches added in slab_cache list may be
sorted by size. i.e. the order they appear in /proc/slabinfo may change
as well.
2. slab_state will be set to UP after KMALLOC_DMA is created.
In case of slub, freelist randomization is dependent on slab_state>=UP,
and therefore KMALLOC_DMA cache's freelist will not be randomized in
creation, but will be deferred to init_freelist_randomization().

Co-developed-by: default avatarJaeSang Yoo <jsyoo5b@gmail.com>
Signed-off-by: default avatarJaeSang Yoo <jsyoo5b@gmail.com>
Signed-off-by: default avatarOhhoon Kwon <ohkwon1043@gmail.com>
Reviewed-by: default avatarHyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Link: https://lore.kernel.org/r/20220410162511.656541-1-ohkwon1043@gmail.com
parent 31231092

mm/slab_common.c

+3 −15
Original line number Diff line number Diff line
@@ -849,6 +849,8 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags) 
			return;

		}

		flags |= SLAB_ACCOUNT;

	} else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) {

		flags |= SLAB_CACHE_DMA;

	}



	kmalloc_caches[type][idx] = create_kmalloc_cache(
@@ -877,7 +879,7 @@ void __init create_kmalloc_caches(slab_flags_t flags) 
	/*

	 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined

	 */

	for (type = KMALLOC_NORMAL; type <= KMALLOC_RECLAIM; type++) {

	for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) {

		for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {

			if (!kmalloc_caches[type][i])

				new_kmalloc_cache(i, type, flags);
@@ -898,20 +900,6 @@ void __init create_kmalloc_caches(slab_flags_t flags) 


	/* Kmalloc array is now usable */

	slab_state = UP;



#ifdef CONFIG_ZONE_DMA

	for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {

		struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i];



		if (s) {

			kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache(

				kmalloc_info[i].name[KMALLOC_DMA],

				kmalloc_info[i].size,

				SLAB_CACHE_DMA | flags, 0,

				kmalloc_info[i].size);

		}

	}

#endif

}

#endif /* !CONFIG_SLOB */