[PATCH 4.6 102/203] percpu: fix synchronization between chunk->map_extend_work and chunk destruction

4.6-stable review patch. If anyone has any objections, please let me know. -- From: Tejun Heo commit 4f996e234dad488e5d9ba0858bc1bae12eff82c3 upstream. Atomic allocations can trigger async map extensions which is serviced by chunk->map_extend_work.

[PATCH 4.6 102/203] percpu: fix synchronization between chunk->map_extend_work and chunk destruction

4.6-stable review patch. If anyone has any objections, please let me know. -- From: Tejun Heo commit 4f996e234dad488e5d9ba0858bc1bae12eff82c3 upstream. Atomic allocations can trigger async map extensions which is serviced by chunk->map_extend_work. pcpu_balance_work which is