On 2025-02-28 11:44:30 [+0100], Yoann Congal wrote: > Hello Linux RT users, Hi, > I got a setup running nested KVM virtual machines on PREEMPT RT kernels > (all 6.12.12 RT kernels from Debian): > The "physical hypervisor" runs "virtual host" VMs which runs guests VMs. > > When using LVM snapshots on the "virtual host" (ie the middle one), I > randomly get a "BUG: scheduling while atomic" trace in the > ext4->dm_snapshot callstack (full trace bellow). It seems to happen more > often when the whole system is loaded. There are multiple BUG traces > each time with slightly different stacks, the deepest common function is > do_origin in [dm_snapshot] [0]. > > Does that ring a bell? > Do you have an advice on how to debug or even fix this? dm_exception_table_lock() is a bit spinlock. This needs to be replaced somehow. I have no idea yet. > Thanks! Sebastian
