linux-kernel - [PATCH 1/2] vmap: cope with vm_unmap_aliases before vmalloc

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Date:	Tue, 28 Oct 2008 19:22:34 +1100
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Nick Piggin <nickpiggin@...oo.com.au>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux Memory Management List <linux-mm@...ck.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: [PATCH 1/2] vmap: cope with vm_unmap_aliases before vmalloc_init()

Xen can end up calling vm_unmap_aliases() before vmalloc_init() has
been called.  In this case its safe to make it a simple no-op.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
---
 mm/vmalloc.c |    7 +++++++
 1 file changed, 7 insertions(+)

===================================================================
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -592,6 +592,8 @@
 
 #define VMAP_BLOCK_SIZE		(VMAP_BBMAP_BITS * PAGE_SIZE)
 
+static bool vmap_initialized __read_mostly = false;
+
 struct vmap_block_queue {
 	spinlock_t lock;
 	struct list_head free;
@@ -828,6 +830,9 @@
 	int cpu;
 	int flush = 0;
 
+	if (unlikely(!vmap_initialized))
+		return;
+
 	for_each_possible_cpu(cpu) {
 		struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
 		struct vmap_block *vb;
@@ -941,6 +946,8 @@
 		INIT_LIST_HEAD(&vbq->dirty);
 		vbq->nr_dirty = 0;
 	}
+
+	vmap_initialized = true;
 }
 
 void unmap_kernel_range(unsigned long addr, unsigned long size)


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