[PATCH 01/20] percpu: fix pcpu_reclaim() locking

Tejun Heo
2009-07-21T10:28:02Z

pcpu_reclaim() calls pcpu_depopulate_chunk() which makes use of pages
array and bitmap returned by pcpu_get_pages_and_bitmap() and thus
should be called under pcpu_alloc_mutex. pcpu_reclaim() released the
mutex before calling depopulate leading to double free and other
strange problems caused by the unexpected concurrent usages of pages
array and bitmap. Fix it.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
mm/percpu.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index f993dc8..c44a5b2 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1181,12 +1181,13 @@ static void pcpu_reclaim(struct work_struct *work)
}

spin_unlock_irq(&pcpu_lock);
- mutex_unlock(&pcpu_alloc_mutex);

list_for_each_entry_safe(chunk, next, &todo, list) {
pcpu_depopulate_chunk(chunk, 0, pcpu_unit_size);
free_pcpu_chunk(chunk);
}
+
+ mutex_unlock(&pcpu_alloc_mutex);
}

/**
--
1.6.0.2