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Commit 3004ec9c authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

userfaultfd: allocate the userfaultfd_ctx cacheline aligned 



Use proper slab to guarantee alignment.

Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Acked-by: default avatarPavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 15b726ef

fs/userfaultfd.c

+31 −8
Original line number Diff line number Diff line
@@ -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 */
@@ -130,7 +136,7 @@ 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);

	}

}
@@ -1028,6 +1034,15 @@ 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.
@@ -1058,14 +1073,11 @@ 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;
@@ -1076,7 +1088,7 @@ 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;

}
@@ -1105,3 +1117,14 @@ SYSCALL_DEFINE1(userfaultfd, int, flags) 


	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);