From c0aac5975bafc86f6817b14e9f71dcb5064a9183 Mon Sep 17 00:00:00 2001 From: Mateusz Guzik Date: Wed, 3 Dec 2025 10:28:50 +0100 Subject: [PATCH] ns: pad refcount Note no effort is made to make sure structs embedding the namespace are themselves aligned, so this is not guaranteed to eliminate cacheline bouncing due to refcount management. Signed-off-by: Mateusz Guzik Link: https://patch.msgid.link/20251203092851.287617-2-mjguzik@gmail.com Signed-off-by: Christian Brauner --- include/linux/ns/ns_common_types.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/ns/ns_common_types.h b/include/linux/ns/ns_common_types.h index b332b019b29cb..0014fbc1c6269 100644 --- a/include/linux/ns/ns_common_types.h +++ b/include/linux/ns/ns_common_types.h @@ -108,11 +108,13 @@ extern const struct proc_ns_operations utsns_operations; * @ns_tree: namespace tree nodes and active reference count */ struct ns_common { + struct { + refcount_t __ns_ref; /* do not use directly */ + } ____cacheline_aligned_in_smp; u32 ns_type; struct dentry *stashed; const struct proc_ns_operations *ops; unsigned int inum; - refcount_t __ns_ref; /* do not use directly */ union { struct ns_tree; struct rcu_head ns_rcu; -- 2.47.3