sparse_index_init() is designed to be safe if two copies of it race. It
uses "index_init_lock" to ensure that, even in the case of a race, only
one CPU will manage to do:
mem_section[root] = section;
However, in the case where two copies of sparse_index_init() _do_ race,
the one that loses the race will leak the "section" that
sparse_index_alloc() allocated for it. This patch fixes that leak.
Signed-off-by: Gavin Shan <shangw@xxxxxxxxxxxxxxxxxx>
---
mm/sparse.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/mm/sparse.c b/mm/sparse.c
index 781fa04..a6984d9 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -75,6 +75,20 @@ static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
return section;
}
+static inline void __meminit sparse_index_free(struct mem_section *section)
+{
+ unsigned long size = SECTIONS_PER_ROOT *
+ sizeof(struct mem_section);
+
+ if (!section)
+ return;
+
+ if (slab_is_available())
+ kfree(section);
+ else
+ free_bootmem(virt_to_phys(section), size);
+}
+
static int __meminit sparse_index_init(unsigned long section_nr, int nid)
{
static DEFINE_SPINLOCK(index_init_lock);
@@ -102,6 +116,9 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
mem_section[root] = section;
out:
spin_unlock(&index_init_lock);
+ if (ret)
+ sparse_index_free(section);
+
return ret;
}
#else /* !SPARSEMEM_EXTREME */
--
1.7.9.5
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