[PATCH] sparsemem extreme: hotplug preparation
This splits up sparse_index_alloc() into two pieces. This is needed
because we'll allocate the memory for the second level in a different place
from where we actually consume it to keep the allocation from happening
underneath a lock
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Bob Picco <bob.picco@hp.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/sparse.c b/mm/sparse.c
index fa01292..347249a 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -6,6 +6,7 @@
#include <linux/mmzone.h>
#include <linux/bootmem.h>
#include <linux/module.h>
+#include <linux/spinlock.h>
#include <asm/dma.h>
/*
@@ -22,27 +23,55 @@
#endif
EXPORT_SYMBOL(mem_section);
-static void sparse_alloc_root(unsigned long root, int nid)
-{
#ifdef CONFIG_SPARSEMEM_EXTREME
- mem_section[root] = alloc_bootmem_node(NODE_DATA(nid), PAGE_SIZE);
-#endif
-}
-
-static void sparse_index_init(unsigned long section, int nid)
+static struct mem_section *sparse_index_alloc(int nid)
{
- unsigned long root = SECTION_NR_TO_ROOT(section);
+ struct mem_section *section = NULL;
+ unsigned long array_size = SECTIONS_PER_ROOT *
+ sizeof(struct mem_section);
- if (mem_section[root])
- return;
+ section = alloc_bootmem_node(NODE_DATA(nid), array_size);
- sparse_alloc_root(root, nid);
+ if (section)
+ memset(section, 0, array_size);
- if (mem_section[root])
- memset(mem_section[root], 0, PAGE_SIZE);
- else
- panic("memory_present: NO MEMORY\n");
+ return section;
}
+
+static int sparse_index_init(unsigned long section_nr, int nid)
+{
+ static spinlock_t index_init_lock = SPIN_LOCK_UNLOCKED;
+ unsigned long root = SECTION_NR_TO_ROOT(section_nr);
+ struct mem_section *section;
+ int ret = 0;
+
+ if (mem_section[root])
+ return -EEXIST;
+
+ section = sparse_index_alloc(nid);
+ /*
+ * This lock keeps two different sections from
+ * reallocating for the same index
+ */
+ spin_lock(&index_init_lock);
+
+ if (mem_section[root]) {
+ ret = -EEXIST;
+ goto out;
+ }
+
+ mem_section[root] = section;
+out:
+ spin_unlock(&index_init_lock);
+ return ret;
+}
+#else /* !SPARSEMEM_EXTREME */
+static inline int sparse_index_init(unsigned long section_nr, int nid)
+{
+ return 0;
+}
+#endif
+
/* Record a memory area against a node. */
void memory_present(int nid, unsigned long start, unsigned long end)
{
