Hi Andriy,

The hardware is AMD.


 Ryzen ?

But what I see suggests that at this point a Local APIC timer interrupt gets
delivered to the thread.  And that causes all the mess as the thread holding the
spinlock gets preempted.

Does this ring a bell to anyone?

I have seen something similar to this after about ~20 mins when doing a current -j 16 buildworld in a guest, with the symptom being a spinlock timeout, with one vCPU spinning in

smp_targeted_tlb_shootdown() at smp_targeted_tlb_shootdown+0x352/frame 0xfffffe02c80098d0
smp_masked_invlpg() at smp_masked_invlpg+0x4c/frame 0xfffffe02c8009900
pmap_invalidate_page() at pmap_invalidate_page+0x191/frame 0xfffffe02c8009950
pmap_ts_referenced() at pmap_ts_referenced+0x7b3/frame 0xfffffe02c8009a00
vm_pageout() at vm_pageout+0xe04/frame 0xfffffe02c8009a70

... and all the others eventually spinning on that held lock.

However, NMIs are still able to get through (the post-panic ddb NMI IPI) so the VM isn't completely locked up - either an interrupt is missed, or a write isn't seen by the vCPU issuing the tlb shootdown.

Is there any suspect code?

Not sure yet, but the interrupt-injection path could do with a close inspection.

It seems that we set v_intr_masking bit, so the rFLAGS / eFLAGS should be
completely virtualized.  So, maybe a hardware issue?

Hard to say. Running with all vCPUs pinned makes the problem go away, but that could just mean the issue is isolated to when vCPUs migrate.

later,

Peter.
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