Hi Maintainers,
A question raised when I learned below code. Appreciate any help me
understand the code.
void native_flush_tlb_others(const struct cpumask *cpumask,
const struct flush_tlb_info *info)
{
...
/*
* If no page tables were freed, we can skip sending IPIs to
* CPUs in lazy TLB mode. They will flush the CPU themselves
* at the next context switch.
*
* However, if page tables are getting freed, we need to send the
* IPI everywhere, to prevent CPUs in lazy TLB mode from tripping
* up on the new contents of what used to be page tables, while
* doing a speculative memory access.
*/
if (info->freed_tables)
smp_call_function_many(cpumask, flush_tlb_func_remote,
(void *)info, 1);
else
on_each_cpu_cond_mask(tlb_is_not_lazy,
flush_tlb_func_remote,
(void *)info, 1, GFP_ATOMIC, cpumask);
}
I just didn't understand how a kernel thread could trip up on the new
contents of what used to be page tables. I presume the freed page tables
are user mapping?
But kernel thread only access kernel address space, is kernel space also
freed?
thanks
Zhenzhong
