Re: [PATCH] PM: domains: Fix sleep-in-atomic bug caused by genpd_debug_remove()

[Rafael J. Wysocki]

On Tue, Mar 1, 2022 at 11:38 AM Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>
> On Fri, 25 Feb 2022 at 07:48, Shawn Guo <shawnguo@xxxxxxxxxx> wrote:
> >
> > From: Shawn Guo <shawn.guo@xxxxxxxxxx>
> >
> > When a genpd with GENPD_FLAG_IRQ_SAFE gets removed, the following
> > sleep-in-atomic bug will be seen, as genpd_debug_remove() will be called
> > with a spinlock being held.
> >
> > [    0.029183] BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1460
> > [    0.029204] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 1, name: swapper/0
> > [    0.029219] preempt_count: 1, expected: 0
> > [    0.029230] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.17.0-rc4+ #489
> > [    0.029245] Hardware name: Thundercomm TurboX CM2290 (DT)
> > [    0.029256] Call trace:
> > [    0.029265]  dump_backtrace.part.0+0xbc/0xd0
> > [    0.029285]  show_stack+0x3c/0xa0
> > [    0.029298]  dump_stack_lvl+0x7c/0xa0
> > [    0.029311]  dump_stack+0x18/0x34
> > [    0.029323]  __might_resched+0x10c/0x13c
> > [    0.029338]  __might_sleep+0x4c/0x80
> > [    0.029351]  down_read+0x24/0xd0
> > [    0.029363]  lookup_one_len_unlocked+0x9c/0xcc
> > [    0.029379]  lookup_positive_unlocked+0x10/0x50
> > [    0.029392]  debugfs_lookup+0x68/0xac
> > [    0.029406]  genpd_remove.part.0+0x12c/0x1b4
> > [    0.029419]  of_genpd_remove_last+0xa8/0xd4
> > [    0.029434]  psci_cpuidle_domain_probe+0x174/0x53c
> > [    0.029449]  platform_probe+0x68/0xe0
> > [    0.029462]  really_probe+0x190/0x430
> > [    0.029473]  __driver_probe_device+0x90/0x18c
> > [    0.029485]  driver_probe_device+0x40/0xe0
> > [    0.029497]  __driver_attach+0xf4/0x1d0
> > [    0.029508]  bus_for_each_dev+0x70/0xd0
> > [    0.029523]  driver_attach+0x24/0x30
> > [    0.029534]  bus_add_driver+0x164/0x22c
> > [    0.029545]  driver_register+0x78/0x130
> > [    0.029556]  __platform_driver_register+0x28/0x34
> > [    0.029569]  psci_idle_init_domains+0x1c/0x28
> > [    0.029583]  do_one_initcall+0x50/0x1b0
> > [    0.029595]  kernel_init_freeable+0x214/0x280
> > [    0.029609]  kernel_init+0x2c/0x13c
> > [    0.029622]  ret_from_fork+0x10/0x20
> >
> > It doesn't seem necessary to call genpd_debug_remove() with the lock, so
> > move it out from locking to fix the problem.
> >
> > Fixes: 718072ceb211 ("PM: domains: create debugfs nodes when adding power domains")
> > Signed-off-by: Shawn Guo <shawn.guo@xxxxxxxxxx>
>
> Thanks for fixing this!
>
> Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>

Applied as 5.18 material.

> Rafael, I think we should tag this for stable kernels too.

Done.

Thanks!