Hi,

I am hitting the below panic when I am testing couple of my drivers. When i
looked at the source, the reason is PSL_I bit (Interrupt enabled) bit is
not set when read in "smp_targeted_tlb_shootdown" routine. But I am
wondering what leads to this.

*Driver test scenario:*
1. Driver has a kernel thread, which allocates memory and dma maps it and
send the dma addr to Driver 2. Then wait (msleep) till it gets a
notification from Driver 2.
2. Driver 2 has a kernel thread which will submit the received address from
Driver1 to hardware and wait (msleep) for an interrupt
3. Driver 2 receives a interrupt and wakes up the thread (wakeup_one) in
Driver2. Thread in Driver 2 then notifies Driver1 through a callback.
4. Callback in Driver 1 wakeup (wakeup_one) it's sleeping kernel thread.
The kernel thread then dma unmap the buffer the frees the memory

Kernel Panics while the memory is freed at last. I am sure this is a
driver, but not sure what am I doing wrong here. Please help.

panic: smp_targeted_tlb_shootdown: interrupts disabled
cpuid = 44
time = 1577463701
KDB: stack backtrace:
#0 0xffffffff80be7977 at kdb_backtrace+0x67
#1 0xffffffff80b9b563 at vpanic+0x1a3
#2 0xffffffff80b9b3b3 at panic+0x43
#3 0xffffffff811eea8f at smp_targeted_tlb_shootdown+0x40f
#4 0xffffffff811eeb22 at smp_masked_invlpg_range+0x42
#5 0xffffffff8105e67c at pmap_invalidate_range+0x25c
#6 0xffffffff81061cdd at pmap_remove_ptes+0x6d
#7 0xffffffff8106079b at pmap_remove+0x35b
#8 0xffffffff80ee0366 at _kmem_unback+0x36
#9 0xffffffff80ee04cd at kmem_free+0x2d
#10 0xffffffff829fc5f8 at driver_thread_work+0x798
#11 0xffffffff80bf9cb4 at taskqueue_run_locked+0x154
#12 0xffffffff80bfae18 at taskqueue_thread_loop+0x98
#13 0xffffffff80b5bf33 at fork_exit+0x83
#14 0xffffffff810501be at fork_trampoline+0xe

Please let me know if any details needed.

Thanks,
Rajesh.
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