Hi Peter,
On Tue, Sep 09, 2025 at 12:14:51PM +0100, Peter Griffin wrote:
> Hi Mostafa,
>
> Thanks for your patch and bug report, it's great to see more folks
> running upstream Pixel 6 :)
>
> On Fri, 5 Sept 2025 at 17:25, Mostafa Saleh <smostafa@xxxxxxxxxx> wrote:
> >
> > Booting the kernel on Pixel-6 with `CONFIG_DEBUG_PREEMPT` prints the
> > following WARN:
> >
> > [ 0.784187][ T1] BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
> > [ 0.784328][ T1] caller is debug_smp_processor_id+0x20/0x30
> > [ 0.784433][ T1] CPU: 6 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.17.0-rc4-gd69eb204c255 #1 PREEMPT
> > [ 0.784439][ T1] Hardware name: Oriole (DT)
> > [ 0.784441][ T1] Call trace:
> > [ 0.784443][ T1] show_stack+0x34/0xa0 (C)
> > [ 0.784453][ T1] dump_stack_lvl+0x7c/0xb0
> > [ 0.784460][ T1] dump_stack+0x18/0x24
> > [ 0.784464][ T1] check_preemption_disabled+0xf8/0x100
> > [ 0.784470][ T1] debug_smp_processor_id+0x20/0x30
> > [ 0.784476][ T1] gs101_cpuhp_pmu_online+0x40/0x108
> > [ 0.784483][ T1] cpuhp_invoke_callback+0x188/0x2d8
> > [ 0.784490][ T1] cpuhp_issue_call+0xec/0x240
> > [ 0.784494][ T1] __cpuhp_setup_state_cpuslocked+0x140/0x2c0
> > [ 0.784499][ T1] __cpuhp_setup_state+0x58/0x88
> > [ 0.784504][ T1] exynos_pmu_probe+0x2a4/0x380
> > [ 0.784508][ T1] platform_probe+0x64/0xd0
> > [ 0.784516][ T1] really_probe+0xd0/0x3b0
> > [ 0.784520][ T1] __driver_probe_device+0x8c/0x170
> > [ 0.784524][ T1] driver_probe_device+0x44/0x140
> > [ 0.784528][ T1] __device_attach_driver+0xd8/0x180
> > [ 0.784532][ T1] bus_for_each_drv+0x90/0xf8
> > [ 0.784536][ T1] __device_attach+0xa8/0x1d0
> > [ 0.784540][ T1] device_initial_probe+0x1c/0x30
> > [ 0.784544][ T1] bus_probe_device+0xb4/0xc0
> > [ 0.784547][ T1] device_add+0x4d0/0x700
> > [ 0.784550][ T1] of_device_add+0x4c/0x78
> > [ 0.784556][ T1] of_platform_device_create_pdata+0x9c/0x148
> > [ 0.784560][ T1] of_platform_bus_create+0x1d0/0x370
> > [ 0.784563][ T1] of_platform_bus_create+0x234/0x370
> > [ 0.784567][ T1] of_platform_populate+0x84/0x178
> > [ 0.784571][ T1] of_platform_default_populate_init+0xf0/0x120
> > [ 0.784579][ T1] do_one_initcall+0x68/0x2d0
> > [ 0.784585][ T1] kernel_init_freeable+0x2d8/0x358
> > [ 0.784589][ T1] kernel_init+0x28/0x168
> > [ 0.784595][ T1] ret_from_fork+0x10/0x20
> >
> > As this value is only read once, it doesn't require to be stable, so
> > just use "raw_smp_processor_id" instead.
>
> Can I ask what baseline you are running when you see this warning?
>
> As this code got refactored recently in commit 78b72897a5c8 ("soc:
> samsung: exynos-pmu: Enable CPU Idle for gs101") which is present in
> linux-next but hasn't made its way to a proper release yet. After this
> patch smp_processor_id() is always called with a raw_spin_lock() held
> (so this warning shouldn't fire).
>
> I just built next-20250909 locally to confirm, and with the above
> patch reverted I see the warning you mention. So in summary I think
> the issue has already been fixed by the above commit.
I am on commit
commit d69eb204c255c35abd9e8cb621484e8074c75eaa
Merge: 68f285e26478 9b2bfdbf43ad
Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Thu Sep 4 09:59:15 2025 -0700
Merge tag 'net-6.17-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Which doesn't have the commit you mentioned as it is in the Maintainer's
tree, thanks for pointing that.
Thanks,
Mostafa
>
> Thanks,
>
> Peter
