@@ -27,20 +27,26 @@
#include <linux/ioctl.h>
#include <linux/security.h>
+static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly;
+
enum userfaultfd_state {
UFFD_STATE_WAIT_API,
UFFD_STATE_RUNNING,
};
+/*
+ * Start with fault_pending_wqh and fault_wqh so they're more likely
+ * to be in the same cacheline.
+ */
struct userfaultfd_ctx {
- /* pseudo fd refcounting */
- atomic_t refcount;
/* waitqueue head for the pending (i.e. not read) userfaults */
wait_queue_head_t fault_pending_wqh;
/* waitqueue head for the userfaults */
wait_queue_head_t fault_wqh;
/* waitqueue head for the pseudo fd to wakeup poll/read */
wait_queue_head_t fd_wqh;
+ /* pseudo fd refcounting */
+ atomic_t refcount;
/* userfaultfd syscall flags */
unsigned int flags;
/* state machine */
@@ -117,7 +123,7 @@ static void userfaultfd_ctx_put(struct userfaultfd_ctx *ctx)
VM_BUG_ON(spin_is_locked(&ctx->fd_wqh.lock));
VM_BUG_ON(waitqueue_active(&ctx->fd_wqh));
mmput(ctx->mm);
- kfree(ctx);
+ kmem_cache_free(userfaultfd_ctx_cachep, ctx);
}
}
@@ -987,6 +993,15 @@ static const struct file_operations userfaultfd_fops = {
.llseek = noop_llseek,
};
+static void init_once_userfaultfd_ctx(void *mem)
+{
+ struct userfaultfd_ctx *ctx = (struct userfaultfd_ctx *) mem;
+
+ init_waitqueue_head(&ctx->fault_pending_wqh);
+ init_waitqueue_head(&ctx->fault_wqh);
+ init_waitqueue_head(&ctx->fd_wqh);
+}
+
/**
* userfaultfd_file_create - Creates an userfaultfd file pointer.
* @flags: Flags for the userfaultfd file.
@@ -1017,14 +1032,11 @@ static struct file *userfaultfd_file_create(int flags)
goto out;
file = ERR_PTR(-ENOMEM);
- ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
+ ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL);
if (!ctx)
goto out;
atomic_set(&ctx->refcount, 1);
- init_waitqueue_head(&ctx->fault_pending_wqh);
- init_waitqueue_head(&ctx->fault_wqh);
- init_waitqueue_head(&ctx->fd_wqh);
ctx->flags = flags;
ctx->state = UFFD_STATE_WAIT_API;
ctx->released = false;
@@ -1035,7 +1047,7 @@ static struct file *userfaultfd_file_create(int flags)
file = anon_inode_getfile("[userfaultfd]", &userfaultfd_fops, ctx,
O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS));
if (IS_ERR(file))
- kfree(ctx);
+ kmem_cache_free(userfaultfd_ctx_cachep, ctx);
out:
return file;
}
@@ -1064,3 +1076,14 @@ err_put_unused_fd:
return error;
}
+
+static int __init userfaultfd_init(void)
+{
+ userfaultfd_ctx_cachep = kmem_cache_create("userfaultfd_ctx_cache",
+ sizeof(struct userfaultfd_ctx),
+ 0,
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC,
+ init_once_userfaultfd_ctx);
+ return 0;
+}
+__initcall(userfaultfd_init);
Use proper slab to guarantee alignment. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> --- fs/userfaultfd.c | 39 +++++++++++++++++++++++++++++++-------- 1 file changed, 31 insertions(+), 8 deletions(-)