mm: percpu: introduce pcpuobj_ext

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.

Link: https://lkml.kernel.org/r/20240321163705.3067592-28-surenb@google.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: linux-mm@kvack.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 17 insertions, 2 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;