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Subject: Re: 5.12-rc1 regression: freezing iou-mgr/wrk failed
To:     "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>,
        linux-kernel@vger.kernel.org, linux-block@vger.kernel.org
References: <1614646241.av51lk2de4.none.ref@localhost>
 <1614646241.av51lk2de4.none@localhost>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <ad672889-2757-142b-9259-3e0aee6d8078@kernel.dk>
Date:   Mon, 1 Mar 2021 18:11:55 -0700
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On 3/1/21 5:57 PM, Alex Xu (Hello71) wrote:
> Hi,
> 
> On Linux 5.12-rc1, I am unable to suspend to RAM. The system freezes for 
> about 40 seconds and then continues operation. The following messages 
> are printed to the kernel log:
> 
> [  240.650300] PM: suspend entry (deep)
> [  240.650748] Filesystems sync: 0.000 seconds
> [  240.725605] Freezing user space processes ...
> [  260.739483] Freezing of tasks failed after 20.013 seconds (3 tasks refusing to freeze, wq_busy=0):
> [  260.739497] task:iou-mgr-446     state:S stack:    0 pid:  516 ppid:   439 flags:0x00004224
> [  260.739504] Call Trace:
> [  260.739507]  ? sysvec_apic_timer_interrupt+0xb/0x81
> [  260.739515]  ? pick_next_task_fair+0x197/0x1cde
> [  260.739519]  ? sysvec_reschedule_ipi+0x2f/0x6a
> [  260.739522]  ? asm_sysvec_reschedule_ipi+0x12/0x20
> [  260.739525]  ? __schedule+0x57/0x6d6
> [  260.739529]  ? del_timer_sync+0xb9/0x115
> [  260.739533]  ? schedule+0x63/0xd5
> [  260.739536]  ? schedule_timeout+0x219/0x356
> [  260.739540]  ? __next_timer_interrupt+0xf1/0xf1
> [  260.739544]  ? io_wq_manager+0x73/0xb1
> [  260.739549]  ? io_wq_create+0x262/0x262
> [  260.739553]  ? ret_from_fork+0x22/0x30
> [  260.739557] task:iou-mgr-517     state:S stack:    0 pid:  522 ppid:   439 flags:0x00004224
> [  260.739561] Call Trace:
> [  260.739563]  ? sysvec_apic_timer_interrupt+0xb/0x81
> [  260.739566]  ? pick_next_task_fair+0x16f/0x1cde
> [  260.739569]  ? sysvec_apic_timer_interrupt+0xb/0x81
> [  260.739571]  ? asm_sysvec_apic_timer_interrupt+0x12/0x20
> [  260.739574]  ? __schedule+0x5b7/0x6d6
> [  260.739578]  ? del_timer_sync+0x70/0x115
> [  260.739581]  ? schedule_timeout+0x211/0x356
> [  260.739585]  ? __next_timer_interrupt+0xf1/0xf1
> [  260.739588]  ? io_wq_check_workers+0x15/0x11f
> [  260.739592]  ? io_wq_manager+0x69/0xb1
> [  260.739596]  ? io_wq_create+0x262/0x262
> [  260.739600]  ? ret_from_fork+0x22/0x30
> [  260.739603] task:iou-wrk-517     state:S stack:    0 pid:  523 ppid:   439 flags:0x00004224
> [  260.739607] Call Trace:
> [  260.739609]  ? __schedule+0x5b7/0x6d6
> [  260.739614]  ? schedule+0x63/0xd5
> [  260.739617]  ? schedule_timeout+0x219/0x356
> [  260.739621]  ? __next_timer_interrupt+0xf1/0xf1
> [  260.739624]  ? task_thread.isra.0+0x148/0x3af
> [  260.739628]  ? task_thread_unbound+0xa/0xa
> [  260.739632]  ? task_thread_bound+0x7/0x7
> [  260.739636]  ? ret_from_fork+0x22/0x30
> [  260.739647] OOM killer enabled.
> [  260.739648] Restarting tasks ... done.
> [  260.740077] PM: suspend exit
> 
> and then a set of similar messages except with s2idle instead of deep.
> 
> Reverting 5695e51619 ("Merge tag 'io_uring-worker.v3-2021-02-25' of 
> git://git.kernel.dk/linux-block") appears to resolve the issue. I have 
> not yet bisected further. Let me know which troubleshooting steps I 
> should perform next.

Can you try and pull in:

git://git.kernel.dk/linux-block io_uring-5.12

and see if that resolves it? I usually always run -git on my laptop as
well, but something broke it in the merge window so I need to figure
out what that is first...

What distro are you running?

-- 
Jens Axboe