It looks like I hit a deadlock between smp_call_function_many() and
cpu_stopper threads.
Where smp_call_function_many() on CPU1 called from
native_flush_tlb_others() waits on call to be complete on
CPU2 while CPU2 waits on state synchronization in
multi_cpu_stop() which can't be completed until stop work
queued on CPU1 is completed, which can't be done since CPU1
is busy looping in smp_call_function_many().
CPU1 CPU2
stop_machine()
queue stop work on cpu 1&2
native_flush_tlb_others()
smp_call_function_many()
...
---------------------------------------------------------
cpu_stopper_thread()
multi_cpu_stop()
do {
...
msdata->state == MULTI_STOP_PREPARE
msdata->active_cpus == 0110
msdata->thread_ack == 1
} while (curstate != MULTI_STOP_EXIT)
waiting until CPU1 ACKs state, i.e.
thread_ack == 0
---------------------------------------------------------
...
if (wait) {
for_cpu(0110) {
csd_lock_wait(csd);
waiting until call on CPU2 is completed
Are there any suggestions on how to fix this nicely?
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