[PATCH v4 26/36] mm: percpu: Introduce pcpuobj_ext

Suren Baghdasaryan
2024-02-21T19:42:12Z

From: Kent Overstreet <kent.overstreet@linux.dev>

Upcoming alloc tagging patches require a place to stash per-allocation
metadata.

We already do this when memcg is enabled, so this patch generalizes the
obj_cgroup * vector in struct pcpu_chunk by creating a pcpu_obj_ext
type, which we will be adding to in an upcoming patch - similarly to the
previous slabobj_ext patch.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: linux-mm@kvack.org
---
mm/percpu-internal.h | 19 +++++++++++++++++--
mm/percpu.c | 30 +++++++++++++++---------------
2 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h
index cdd0aa597a81..e62d582f4bf3 100644
--- a/mm/percpu-internal.h
+++ b/mm/percpu-internal.h
@@ -32,6 +32,16 @@ struct pcpu_block_md {
int nr_bits; /* total bits responsible for */
};

+struct pcpuobj_ext {
+#ifdef CONFIG_MEMCG_KMEM
+ struct obj_cgroup *cgroup;
+#endif
+};
+
+#ifdef CONFIG_MEMCG_KMEM
+#define NEED_PCPUOBJ_EXT
+#endif
+
struct pcpu_chunk {
#ifdef CONFIG_PERCPU_STATS
int nr_alloc; /* # of allocations */
@@ -64,8 +74,8 @@ struct pcpu_chunk {
int end_offset; /* additional area required to
have the region end page
aligned */
-#ifdef CONFIG_MEMCG_KMEM
- struct obj_cgroup **obj_cgroups; /* vector of object cgroups */
+#ifdef NEED_PCPUOBJ_EXT
+ struct pcpuobj_ext *obj_exts; /* vector of object cgroups */
#endif

int nr_pages; /* # of pages served by this chunk */
@@ -74,6 +84,11 @@ struct pcpu_chunk {
unsigned long populated[]; /* populated bitmap */
};

+static inline bool need_pcpuobj_ext(void)
+{
+ return !mem_cgroup_kmem_disabled();
+}
+
extern spinlock_t pcpu_lock;

extern struct list_head *pcpu_chunk_lists;
diff --git a/mm/percpu.c b/mm/percpu.c
index 4e11fc1e6def..2e5edaad9cc3 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1392,9 +1392,9 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
panic("%s: Failed to allocate %zu bytes\n", __func__,
alloc_size);

-#ifdef CONFIG_MEMCG_KMEM
+#ifdef NEED_PCPUOBJ_EXT
/* first chunk is free to use */
- chunk->obj_cgroups = NULL;
+ chunk->obj_exts = NULL;
#endif
pcpu_init_md_blocks(chunk);

@@ -1463,12 +1463,12 @@ static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
if (!chunk->md_blocks)
goto md_blocks_fail;

-#ifdef CONFIG_MEMCG_KMEM
- if (!mem_cgroup_kmem_disabled()) {
- chunk->obj_cgroups =
+#ifdef NEED_PCPUOBJ_EXT
+ if (need_pcpuobj_ext()) {
+ chunk->obj_exts =
pcpu_mem_zalloc(pcpu_chunk_map_bits(chunk) *
- sizeof(struct obj_cgroup *), gfp);
- if (!chunk->obj_cgroups)
+ sizeof(struct pcpuobj_ext), gfp);
+ if (!chunk->obj_exts)
goto objcg_fail;
}
#endif
@@ -1480,7 +1480,7 @@ static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)

return chunk;

-#ifdef CONFIG_MEMCG_KMEM
+#ifdef NEED_PCPUOBJ_EXT
objcg_fail:
pcpu_mem_free(chunk->md_blocks);
#endif
@@ -1498,8 +1498,8 @@ static void pcpu_free_chunk(struct pcpu_chunk *chunk)
{
if (!chunk)
return;
-#ifdef CONFIG_MEMCG_KMEM
- pcpu_mem_free(chunk->obj_cgroups);
+#ifdef NEED_PCPUOBJ_EXT
+ pcpu_mem_free(chunk->obj_exts);
#endif
pcpu_mem_free(chunk->md_blocks);
pcpu_mem_free(chunk->bound_map);
@@ -1646,9 +1646,9 @@ static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
if (!objcg)
return;

- if (likely(chunk && chunk->obj_cgroups)) {
+ if (likely(chunk && chunk->obj_exts)) {
obj_cgroup_get(objcg);
- chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg;
+ chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].cgroup = objcg;

rcu_read_lock();
mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
@@ -1663,13 +1663,13 @@ static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
{
struct obj_cgroup *objcg;

- if (unlikely(!chunk->obj_cgroups))
+ if (unlikely(!chunk->obj_exts))
return;

- objcg = chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT];
+ objcg = chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].cgroup;
if (!objcg)
return;
- chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = NULL;
+ chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].cgroup = NULL;

obj_cgroup_uncharge(objcg, pcpu_obj_full_size(size));

--
2.44.0.rc0.258.g7320e95886-goog