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 1291523f2c1d ("mm, slab/slub: introduce kmalloc-reclaimable
caches") and KMALLOC_CGROUP was introduced in v5.14 via
commit 494c1dfe855e ("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: JaeSang Yoo <[email protected]>
Signed-off-by: JaeSang Yoo <[email protected]>
Signed-off-by: Ohhoon Kwon <[email protected]>
---
mm/slab_common.c | 20 +++++---------------
1 file changed, 5 insertions(+), 15 deletions(-)
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 6ee64d6208b3..eb95512de983 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -849,6 +849,10 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
return;
}
flags |= SLAB_ACCOUNT;
+#ifdef CONFIG_ZONE_DMA
+ } else if (type == KMALLOC_DMA) {
+ flags |= SLAB_CACHE_DMA;
+#endif
}
kmalloc_caches[type][idx] = create_kmalloc_cache(
@@ -877,7 +881,7 @@ 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 +902,6 @@ 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 */
--
2.25.1
On Sat, Apr 09, 2022 at 06:53:05PM +0900, Ohhoon Kwon wrote:
> 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 1291523f2c1d ("mm, slab/slub: introduce kmalloc-reclaimable
> caches") and KMALLOC_CGROUP was introduced in v5.14 via
> commit 494c1dfe855e ("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: JaeSang Yoo <[email protected]>
> Signed-off-by: JaeSang Yoo <[email protected]>
> Signed-off-by: Ohhoon Kwon <[email protected]>
> ---
> mm/slab_common.c | 20 +++++---------------
> 1 file changed, 5 insertions(+), 15 deletions(-)
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 6ee64d6208b3..eb95512de983 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -849,6 +849,10 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
> return;
> }
> flags |= SLAB_ACCOUNT;
> +#ifdef CONFIG_ZONE_DMA
> + } else if (type == KMALLOC_DMA) {
> + flags |= SLAB_CACHE_DMA;
> +#endif
Maybe IS_ENABLED() would be better instead of ifdef for consistency?
> }
>
> kmalloc_caches[type][idx] = create_kmalloc_cache(
> @@ -877,7 +881,7 @@ 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 +902,6 @@ 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 */
The patch overall looks good to me.
Reviewed-by: Hyeonggon Yoo <[email protected]>
Thanks!
> --
> 2.25.1
>
>
--
Thanks,
Hyeonggon