diff options
| author | Christian Brauner <brauner@kernel.org> | 2024-08-28 12:56:24 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-08-29 15:20:32 +0200 |
| commit | d345bd2e9834e2da505977e154a1c179c793b7b2 (patch) | |
| tree | 5bd9bfdb853f72c587a0986039d990c3f2a96114 /mm/slab.h | |
| parent | e446f18e98e89fb7de2b320620ce983929bb2486 (diff) | |
mm: add kmem_cache_create_rcu()
When a kmem cache is created with SLAB_TYPESAFE_BY_RCU the free pointer
must be located outside of the object because we don't know what part of
the memory can safely be overwritten as it may be needed to prevent
object recycling.
That has the consequence that SLAB_TYPESAFE_BY_RCU may end up adding a
new cacheline. This is the case for e.g., struct file. After having it
shrunk down by 40 bytes and having it fit in three cachelines we still
have SLAB_TYPESAFE_BY_RCU adding a fourth cacheline because it needs to
accommodate the free pointer.
Add a new kmem_cache_create_rcu() function that allows the caller to
specify an offset where the free pointer is supposed to be placed.
Link: https://lore.kernel.org/r/20240828-work-kmem_cache-rcu-v3-2-5460bc1f09f6@kernel.org
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'mm/slab.h')
| -rw-r--r-- | mm/slab.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/slab.h b/mm/slab.h index dcdb56b8e7f5..a6051385186e 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -261,6 +261,8 @@ struct kmem_cache { unsigned int object_size; /* Object size without metadata */ struct reciprocal_value reciprocal_size; unsigned int offset; /* Free pointer offset */ + /* Specific free pointer requested (if not UINT_MAX) */ + unsigned int rcu_freeptr_offset; #ifdef CONFIG_SLUB_CPU_PARTIAL /* Number of per cpu partial objects to keep around */ unsigned int cpu_partial; |