Re: [PATCH] scsi: sd: Revert "Rework asynchronous resume support"

[Bart Van Assche <bvanassche@acm.org>]

On 8/22/22 23:41, Geert Uytterhoeven wrote:
> A lock-up (magic sysrq does not work) during s2idle.
> I tried bisecting it yesterday, but failed.
> On v6.0-rc1 (and rc2) it happens ca. 25% of the time, but the closer
> I get to v5.19, the less likely it is to happen. Apparently 100
> successful s2idle cycles was not enough to declare a kernel good...
> 
>      Freezing ...
>      Filesystems sync: 0.001 seconds
>      Freezing user space processes ... (elapsed 0.001 seconds) done.
>      OOM killer disabled.
>      Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
>      sd 0:0:0:0: [sda] Synchronizing SCSI cache
>      sd 0:0:0:0: [sda] Stopping disk
> 
> ---> hangs here if it happens
> 
>      ravb e6800000.ethernet eth0: Link is Down
>      sd 0:0:0:0: [sda] Starting disk
>      Micrel KSZ9031 Gigabit PHY e6800000.ethernet-ffffffff:00: attached
> PHY driver (mii_bus:phy_addr=e6800000.ethernet-ffffffff:00, irq=186)
>      ata1: link resume succeeded after 1 retries
>      ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
>      ata1.00: configured for UDMA/133
>      OOM killer enabled.
>      Restarting tasks ... done.
>      random: crng reseeded on system resumption
>      PM: suspend exit
>      ravb e6800000.ethernet eth0: Link is Up - 1Gbps/Full - flow control off

Hi Geert,

I'm not sure that is enough information to find the root cause. How 
about enabling the tp_printk boot option and to enable tracing for 
suspend/resume operations, e.g. as follows?

cd /sys/kernel/tracing &&
echo 256 > /sys/kernel/tracing/buffer_size_kb &&
echo nop > current_tracer &&
echo > trace &&
echo 1 > events/power/device_pm_callback_start/enable &&
echo 1 > events/power/device_pm_callback_end/enable &&
echo 1 > events/power/suspend_resume/enable &&
echo 1 > tracing_on

Thanks,

Bart.