On Mon, 3 Nov 2025 11:34:34 +0100, Sebastian Andrzej Siewior wrote: > On 2025-11-03 11:08:35 [+0100], Michal Pecio wrote: > > Hi, > Hi, > > > There is a regression report on a distribution forum which involves > > an out of tree module on a patched kernel (yes, I know) calling > > stack_trace_save() in task context, which arrives here and apparently > > calls the various deref_stack_xxx() functions with preemption enabled, > > which in turn call stack_access_ok() leading to a BUG: > > > > Nov 02 21:44:30 ArchBasement kernel: BUG: using smp_processor_id() in > > preemptible [00000000] code: Xorg/1183 > > Nov 02 21:44:30 ArchBasement kernel: caller is in_entry_stack+0x11/0x60 > > Nov 02 21:44:30 ArchBasement kernel: CPU: 0 UID: 1000 PID: 1183 Comm: Xorg > > Tainted: P OE 6.16.12-hardened1-1-hardened #1 PREEMPT(full) > > 6edb90a7a07fab33bbee72d6d5ef53ba6eec3b9c > > Nov 02 21:44:30 ArchBasement kernel: Tainted: [P]=PROPRIETARY_MODULE, > > [O]=OOT_MODULE, [E]=UNSIGNED_MODULE > > Nov 02 21:44:30 ArchBasement kernel: Hardware name: ASUS All Series/Z97-E, > > BIOS 0803 02/23/2016 > > Nov 02 21:44:30 ArchBasement kernel: Call Trace: > > Nov 02 21:44:30 ArchBasement kernel: <TASK> > > Nov 02 21:44:30 ArchBasement kernel: dump_stack_lvl+0x5d/0x80 > > Nov 02 21:44:30 ArchBasement kernel: check_preemption_disabled+0xe5/0xf0 > > Nov 02 21:44:30 ArchBasement kernel: in_entry_stack+0x11/0x60 > > Nov 02 21:44:30 ArchBasement kernel: get_stack_info+0x2c/0x80 > > Nov 02 21:44:30 ArchBasement kernel: stack_access_ok+0x51/0xa0 > > Nov 02 21:44:30 ArchBasement kernel: unwind_next_frame+0x1cb/0x7b0 > > Nov 02 21:44:30 ArchBasement kernel: ? _nv003168kms+0x42/0x50 > > [nvidia_modeset 90775ea8a26c5e58b97ef4b3f46eb45efa040eb2] > > Nov 02 21:44:30 ArchBasement kernel: ? > > __pfx_stack_trace_consume_entry+0x10/0x10 > > Nov 02 21:44:30 ArchBasement kernel: arch_stack_walk+0xa6/0x110 > > Nov 02 21:44:30 ArchBasement kernel: ? _nv003168kms+0x42/0x50 > > [nvidia_modeset 90775ea8a26c5e58b97ef4b3f46eb45efa040eb2] > > Nov 02 21:44:30 ArchBasement kernel: stack_trace_save+0x4d/0x70 > > > > Is this nvidia doing something wrong, or a problem with this commit? > > > > The removed code suggests that preemption is allowed here, and as far > > as I see, this call trace is still possible on vanilla 6.18. Perhaps > > preempt_disable() needs to be restored around this code? > > Do you have the complete backtrace? Is this SMP or UP build?
Sorry, I forgot to include the link. There is also a similar warning regarding __this_cpu_read(). Pretty sure the kernel is SMP. https://bbs.archlinux.org/viewtopic.php?id=309960
