On 17.03.25 14:29, Andrew Cooper wrote:
On 17/03/2025 1:21 pm, Choi, Anderson wrote:Jürgen,On 17.03.25 06:07, Choi, Anderson wrote:I'd like to report xen panic when shutting down an ARINC653 domain with the following setup. Note that this is only observed when CONFIG_DEBUG is enabled. [Test environment] Yocto release : 5.05 Xen release : 4.19 (hash = 026c9fa29716b0ff0f8b7c687908e71ba29cf239) Target machine : QEMU ARM64 Number of physical CPUs : 4 [Xen config] CONFIG_DEBUG = y [CPU pool configuration files] cpupool_arinc0.cfg - name= "Pool-arinc0" - sched="arinc653" - cpus=["2"] [Domain configuration file] dom1.cfg - vcpus = 1 - pool = "Pool-arinc0" $ xl cpupool-cpu-remove Pool-0 2 $ xl cpupool-create -f cpupool_arinc0.cfg $ xl create dom1.cfg $ a653_sched -P Pool-arinc0 dom1:100 ** Wait for DOM1 to complete boot.** $ xl shutdown dom1 [xen log] root@boeing-linux-ref:~# xl shutdown dom1 Shutting down domain 1 root@boeing-linux-ref:~# (XEN) Assertion '!in_irq() && (local_irq_is_enabled() || num_online_cpus() <= 1)' failed at common/xmalloc_tlsf.c:714 (XEN) ----[ Xen-4.19.1-pre arm64 debug=y Tainted: I ]---- (XEN) CPU: 2 (XEN) PC: 00000a000022d2b0 xfree+0x130/0x1a4 (XEN) LR: 00000a000022d2a4 (XEN) SP: 00008000fff77b50 (XEN) CPSR: 00000000200002c9 MODE:64-bit EL2h (Hypervisor, handler) ... (XEN) Xen call trace: (XEN) [<00000a000022d2b0>] xfree+0x130/0x1a4 (PC) (XEN) [<00000a000022d2a4>] xfree+0x124/0x1a4 (LR) (XEN) [<00000a00002321f0>] arinc653.c#a653sched_free_udata+0x50/0xc4 (XEN) [<00000a0000241bc0>] core.c#sched_move_domain_cleanup+0x5c/0x80 (XEN) [<00000a0000245328>] sched_move_domain+0x69c/0x70c (XEN) [<00000a000022f840>] cpupool.c#cpupool_move_domain_locked+0x38/0x70 (XEN) [<00000a0000230f20>] cpupool_move_domain+0x34/0x54 (XEN) [<00000a0000206c40>] domain_kill+0xc0/0x15c (XEN) [<00000a000022e0d4>] do_domctl+0x904/0x12ec (XEN) [<00000a0000277a1c>] traps.c#do_trap_hypercall+0x1f4/0x288 (XEN) [<00000a0000279018>] do_trap_guest_sync+0x448/0x63c (XEN) [<00000a0000262c80>] entry.o#guest_sync_slowpath+0xa8/0xd8 (XEN) (XEN) (XEN) **************************************** (XEN) Panic on CPU 2: (XEN) Assertion '!in_irq() && (local_irq_is_enabled() || num_online_cpus() <= 1)' failed at common/xmalloc_tlsf.c:714 (XEN) **************************************** In commit 19049f8d (sched: fix locking in a653sched_free_vdata()), lockingwas introduced to prevent a race against the list manipulation but leads to assertion failure when the ARINC 653 domain is shutdown.I think this can be fixed by calling xfree() after spin_unlock_irqrestore() as shown below. xen/common/sched/arinc653.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/xen/common/sched/arinc653.c b/xen/common/sched/arinc653.c index 7bf288264c..1615f1bc46 100644 --- a/xen/common/sched/arinc653.c +++ b/xen/common/sched/arinc653.c @@ -463,10 +463,11 @@ a653sched_free_udata(const struct scheduler *ops,void *priv)if ( !is_idle_unit(av->unit) ) list_del(&av->list); - xfree(av); update_schedule_units(ops);spin_unlock_irqrestore(&sched_priv->lock, flags);+ + xfree(av); } Can I hear your opinion on this?Yes, this seems the right way to fix the issue. Could you please send a proper patch (please have a look at [1] in case you are unsure how a proper patch should look like)? Juergen [1] http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/process/sending - patches.pandocThanks for your opinion. Let me read through the link and submit the patch.Other good references are: https://lore.kernel.org/xen-devel/20250313093157.30450-1-jgr...@suse.com/ https://lore.kernel.org/xen-devel/d8c08c22-ee70-4c06-8fcd-ad44fc0dc...@suse.com/ One you hopefully recognise, and the other is another bugfix to ARINC noticed by the Coverity run over the weekend.
Please note that the Coverity report is not about a real bug, but just a latent one. As long as the arinc653 scheduler is supporting a single physical cpu only, there is no real need for the lock when accessing sched_priv->next_switch_time (the lock is thought to protect the list of units/vcpus, not all the other fields of sched_priv). Juergen
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