On 03.04.2025 23:48, Stewart Hildebrand wrote: > The following sequence of events may lead a debug build of Xen to crash > when using the null scheduler: > > 1. domain creation (e.g. d1) failed due to bad configuration > 2. complete_domain_destroy() was deferred > 3. domain creation (e.g. d2) succeeds > > At this point, d2 is running, while the zombie d1 is not fully cleaned > up: > > (XEN) Online Cpus: 0-3 > (XEN) Cpupool 0: > (XEN) Cpus: 0-3 > (XEN) Scheduling granularity: cpu, 1 CPU per sched-resource > (XEN) Scheduler: null Scheduler (null) > (XEN) cpus_free = 3 > (XEN) Domain info: > (XEN) Domain: 0 > (XEN) 1: [0.0] pcpu=0 > (XEN) 2: [0.1] pcpu=1 > (XEN) Domain: 1 > (XEN) 3: [1.0] pcpu=2 > (XEN) Domain: 2 > (XEN) 4: [2.0] pcpu=2 > > 4. complete_domain_destroy() gets called for d1 and triggers the > following: > > (XEN) Xen call trace: > (XEN) [<00000a0000322ed4>] null.c#unit_deassign+0x2d8/0xb70 (PC) > (XEN) [<00000a000032457c>] null.c#null_unit_remove+0x670/0xba8 (LR) > (XEN) [<00000a000032457c>] null.c#null_unit_remove+0x670/0xba8 > (XEN) [<00000a0000336404>] sched_destroy_vcpu+0x354/0x8fc > (XEN) [<00000a0000227324>] domain.c#complete_domain_destroy+0x11c/0x49c > (XEN) [<00000a000029fbd0>] rcupdate.c#rcu_do_batch+0x94/0x3d0 > (XEN) [<00000a00002a10c0>] rcupdate.c#__rcu_process_callbacks+0x160/0x5f4 > (XEN) [<00000a00002a1e60>] rcupdate.c#rcu_process_callbacks+0xcc/0x1b0 > (XEN) [<00000a00002a3460>] softirq.c#__do_softirq+0x1f4/0x3d8 > (XEN) [<00000a00002a37c4>] do_softirq+0x14/0x1c > (XEN) [<00000a0000465260>] traps.c#check_for_pcpu_work+0x30/0xb8 > (XEN) [<00000a000046bb08>] leave_hypervisor_to_guest+0x28/0x198 > (XEN) [<00000a0000409c84>] entry.o#guest_sync_slowpath+0xac/0xd8 > (XEN) > (XEN) **************************************** > (XEN) Panic on CPU 0: > (XEN) Assertion 'npc->unit == unit' failed at common/sched/null.c:383 > (XEN) **************************************** > > Fix by skipping unit_deassign() when the unit to be removed does not > match the pcpu's currently assigned unit. > > Signed-off-by: Stewart Hildebrand <stewart.hildebr...@amd.com>
Just one remark here: This almost certainly wants a Fixes: tag. Jan
