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authorAndrea Arcangeli <aarcange@redhat.com>2015-09-04 15:46:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-04 16:54:41 -0700
commit3004ec9cabf49f43fae2b2bd1855a4720f1def7a (patch)
treed323151df9559ac13d28b84817a2c695fbeea17d /fs
parent15b726ef048b31a24b3fefb6863083a25fe34800 (diff)
userfaultfd: allocate the userfaultfd_ctx cacheline aligned
Use proper slab to guarantee alignment. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Pavel 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/userfaultfd.c39
1 files changed, 31 insertions, 8 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 232cbf37c59f..8977a4e8a7f8 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -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 @@ 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);

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