Commit 971f3918 authored Aug 14, 2009 by Tejun Heo

percpu: fix pcpu_reclaim() locking



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>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>

parent 384be2b1

mm/percpu.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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);
		}

		/**