Re: [PATCH 5/7] scsi: ufs: core: Simplify ufshcd_err_handling_prepare()

[Peter Wang (王信友) <peter.wang@xxxxxxxxxxxx>]

On Wed, 2024-10-16 at 14:11 -0700, Bart Van Assche wrote:
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>  Use blk_mq_quiesce_tagset() instead of ufshcd_scsi_block_requests()
> and blk_mq_wait_quiesce_done().
> 
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
> 

Hi Bart,

Using blk_mq_quiesce_tagset instead of ufshcd_scsi_block_requests 
could cause issues. After the patch below was merged, Mediatek 
received three cases of IO hang.
77691af484e2 ("scsi: ufs: core: Quiesce request queues before checking
pending cmds")
I think this patch might need to be reverted first.

Here is backtrace of IO hang.
ppid=3952 pid=3952 D cpu=6 prio=120 wait=188s kworker/u16:0
	vmlinux __synchronize_srcu() + 216
</proc/self/cwd/common/kernel/rcu/srcutree.c:1386>
	vmlinux synchronize_srcu() + 276
</proc/self/cwd/common/kernel/rcu/srcutree.c:0>
	vmlinux blk_mq_wait_quiesce_done() + 20
</proc/self/cwd/common/block/blk-mq.c:226>
	vmlinux blk_mq_quiesce_tagset() + 156
</proc/self/cwd/common/block/blk-mq.c:286>
	vmlinux ufshcd_clock_scaling_prepare(timeout_us=1000000) + 16
</proc/self/cwd/common/drivers/ufs/core/ufshcd.c:1276>
	vmlinux ufshcd_devfreq_scale() + 52
</proc/self/cwd/common/drivers/ufs/core/ufshcd.c:1322>
	vmlinux ufshcd_devfreq_target() + 384
</proc/self/cwd/common/drivers/ufs/core/ufshcd.c:1440>
	vmlinux devfreq_set_target(flags=0) + 184
</proc/self/cwd/common/drivers/devfreq/devfreq.c:363>
	vmlinux devfreq_update_target(freq=0) + 296
</proc/self/cwd/common/drivers/devfreq/devfreq.c:429>
	vmlinux update_devfreq() + 8
</proc/self/cwd/common/drivers/devfreq/devfreq.c:444>
	vmlinux devfreq_monitor() + 48
</proc/self/cwd/common/drivers/devfreq/devfreq.c:460>
	vmlinux process_one_work() + 476
</proc/self/cwd/common/kernel/workqueue.c:2643>
	vmlinux process_scheduled_works() + 580
</proc/self/cwd/common/kernel/workqueue.c:2717>
	vmlinux worker_thread() + 576
</proc/self/cwd/common/kernel/workqueue.c:2798>
	vmlinux kthread() + 272
</proc/self/cwd/common/kernel/kthread.c:388>
	vmlinux 0xFFFFFFE239A164EC()
</proc/self/cwd/common/arch/arm64/kernel/entry.S:846>

Thanks
Peter