linux-kernel - [RFC PATCH 09/15] make filp and bfilp caches static-duration

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Message-ID: <20260110040217.1927971-10-viro@zeniv.linux.org.uk>
Date: Sat, 10 Jan 2026 04:02:11 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: linux-mm@...ck.org
Cc: Vlastimil Babka <vbabka@...e.cz>,
	Harry Yoo <harry.yoo@...cle.com>,
	linux-fsdevel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Christian Brauner <brauner@...nel.org>,
	Jan Kara <jack@...e.cz>,
	Mateusz Guzik <mguzik@...il.com>,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH 09/15] make filp and bfilp caches static-duration

As much as I hate it, the name "filp" is a part of userland ABI at this
point - scripts grepping for it in /proc/slabinfo do exist ;-/

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/file_table.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/fs/file_table.c b/fs/file_table.c
index cd4a3db4659a..18a992b40109 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -27,6 +27,7 @@
 #include <linux/task_work.h>
 #include <linux/swap.h>
 #include <linux/kmemleak.h>
+#include <linux/slab-static.h>
 
 #include <linux/atomic.h>
 
@@ -38,8 +39,10 @@ static struct files_stat_struct files_stat = {
 };
 
 /* SLAB cache for file structures */
-static struct kmem_cache *filp_cachep __ro_after_init;
-static struct kmem_cache *bfilp_cachep __ro_after_init;
+static struct kmem_cache_opaque file_cache;
+static struct kmem_cache_opaque backing_file_cache;
+#define filp_cachep to_kmem_cache(&file_cache)
+#define bfilp_cachep to_kmem_cache(&backing_file_cache)
 
 static struct percpu_counter nr_files __cacheline_aligned_in_smp;
 
@@ -587,19 +590,20 @@ void fput_close(struct file *file)
 
 void __init files_init(void)
 {
-	struct kmem_cache_args args = {
-		.use_freeptr_offset = true,
-		.freeptr_offset = offsetof(struct file, f_freeptr),
-	};
-
-	filp_cachep = kmem_cache_create("filp", sizeof(struct file), &args,
-				SLAB_HWCACHE_ALIGN | SLAB_PANIC |
-				SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU);
+	__KMEM_CACHE_SETUP(filp_cachep, "filp", sizeof(struct file),
+			   SLAB_HWCACHE_ALIGN | SLAB_PANIC |
+			   SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU,
+			   .use_freeptr_offset = true,
+			   .freeptr_offset = offsetof(struct file,
+						      f_freeptr));
+
+	__KMEM_CACHE_SETUP(bfilp_cachep, "bfilp", sizeof(struct backing_file),
+			   SLAB_HWCACHE_ALIGN | SLAB_PANIC |
+			   SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU,
+			   .use_freeptr_offset = true,
+			   .freeptr_offset = offsetof(struct backing_file,
+						      bf_freeptr));
 
-	args.freeptr_offset = offsetof(struct backing_file, bf_freeptr);
-	bfilp_cachep = kmem_cache_create("bfilp", sizeof(struct backing_file),
-				&args, SLAB_HWCACHE_ALIGN | SLAB_PANIC |
-				SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU);
 	percpu_counter_init(&nr_files, 0, GFP_KERNEL);
 }
 
-- 
2.47.3