On 02-07-18, 17:02, Geert Uytterhoeven wrote:
> During system reboot or halt, with lockdep enabled:
>
> ================================
> WARNING: inconsistent lock state
> 4.18.0-rc1-salvator-x-00002-g9203dbec90a68103 #41 Tainted: G W
> --------------------------------
> inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
> reboot/2779 [HC0[0]:SC0[0]:HE1:SE1] takes:
> 0000000098ae4ad3 (&(&rchan->lock)->rlock){?.-.}, at:
> rcar_dmac_shutdown+0x58/0x6c
> {IN-HARDIRQ-W} state was registered at:
> lock_acquire+0x208/0x238
> _raw_spin_lock+0x40/0x54
> rcar_dmac_isr_channel+0x28/0x200
> __handle_irq_event_percpu+0x1c0/0x3c8
> handle_irq_event_percpu+0x34/0x88
> handle_irq_event+0x48/0x78
> handle_fasteoi_irq+0xc4/0x12c
> generic_handle_irq+0x18/0x2c
> __handle_domain_irq+0xa8/0xac
> gic_handle_irq+0x78/0xbc
> el1_irq+0xec/0x1c0
> arch_cpu_idle+0xe8/0x1bc
> default_idle_call+0x2c/0x30
> do_idle+0x144/0x234
> cpu_startup_entry+0x20/0x24
> rest_init+0x27c/0x290
> start_kernel+0x430/0x45c
> irq event stamp: 12177
> hardirqs last enabled at (12177): [<ffffff800881d804>]
> _raw_spin_unlock_irq+0x2c/0x4c
> hardirqs last disabled at (12176): [<ffffff800881d638>]
> _raw_spin_lock_irq+0x1c/0x60
> softirqs last enabled at (11948): [<ffffff8008081da8>]
> __do_softirq+0x160/0x4ec
> softirqs last disabled at (11935): [<ffffff80080ec948>] irq_exit+0xa0/0xfc
>
> other info that might help us debug this:
> Possible unsafe locking scenario:
>
> CPU0
> ----
> lock(&(&rchan->lock)->rlock);
> <Interrupt>
> lock(&(&rchan->lock)->rlock);
>
> *** DEADLOCK ***
>
> 3 locks held by reboot/2779:
> #0: 00000000bfabfa74 (reboot_mutex){+.+.}, at: sys_reboot+0xdc/0x208
> #1: 00000000c75d8c3a (&dev->mutex){....}, at: device_shutdown+0xc8/0x1c4
> #2: 00000000ebec58ec (&dev->mutex){....}, at: device_shutdown+0xd8/0x1c4
>
> stack backtrace:
> CPU: 6 PID: 2779 Comm: reboot Tainted: G W
> 4.18.0-rc1-salvator-x-00002-g9203dbec90a68103 #41
> Hardware name: Renesas Salvator-X 2nd version board based on r8a7795
> ES2.0+ (DT)
> Call trace:
> dump_backtrace+0x0/0x148
> show_stack+0x14/0x1c
> dump_stack+0xb0/0xf0
> print_usage_bug.part.26+0x1c4/0x27c
> mark_lock+0x38c/0x610
> __lock_acquire+0x3fc/0x14d4
> lock_acquire+0x208/0x238
> _raw_spin_lock+0x40/0x54
> rcar_dmac_shutdown+0x58/0x6c
> platform_drv_shutdown+0x20/0x2c
> device_shutdown+0x160/0x1c4
> kernel_restart_prepare+0x34/0x3c
> kernel_restart+0x14/0x5c
> sys_reboot+0x160/0x208
> el0_svc_naked+0x30/0x34
>
> rcar_dmac_stop_all_chan() takes the channel lock while stopping a
> channel, but does not disable interrupts, leading to a deadlock when a
> DMAC interrupt comes in. Before, the same code block was called from an
> interrupt handler, hence taking the spinlock was sufficient.
>
> Fix this by disabling local interrupts while taking the spinlock.
Applied, thanks
--
~Vinod
