When switch_mm with thread migration, Why flush instruction cache ?

[Li Haifeng]

Can someone tell me why flush instruction cache @118 Line below, when
switch_mm with thread migration from other ARM core.

107 static inline void
108 switch_mm(struct mm_struct *prev, struct mm_struct *next,
109           struct task_struct *tsk)
110 {
111 #ifdef CONFIG_MMU
112         unsigned int cpu = smp_processor_id();
113
114 #ifdef CONFIG_SMP
115         /* check for possible thread migration */
116         if (!cpumask_empty(mm_cpumask(next)) &&
117             !cpumask_test_cpu(cpu, mm_cpumask(next)))
118                 __flush_icache_all();
119 #endif
...
130 #endif
131 }