Re: Re: "mm: move pcp and lru-pcp draining into single wq" broke resume from s2ram

[Geert Uytterhoeven <geert@linux-m68k.org>]

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Hi Tetsuo,

On Wed, Apr 19, 2017 at 7:41 AM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
> Geert Uytterhoeven wrote:
>> 8 locks held by s2ram/1899:
>>  #0:  (sb_writers#7){.+.+.+}, at: [<ffffff80081ca1a4>] vfs_write+0xa8/0x15c
>>  #1:  (&of->mutex){+.+.+.}, at: [<ffffff8008245964>] kernfs_fop_write+0xf0/0x194
>>  #2:  (s_active#48){.+.+.+}, at: [<ffffff800824596c>] kernfs_fop_write+0xf8/0x194
>>  #3:  (pm_mutex){+.+.+.}, at: [<ffffff80081059a4>] pm_suspend+0x16c/0xabc
>>  #4:  (&dev->mutex){......}, at: [<ffffff80083d4920>] device_resume+0x58/0x190
>>  #5:  (cma_mutex){+.+...}, at: [<ffffff80081c516c>] cma_alloc+0x150/0x374
>>  #6:  (lock){+.+...}, at: [<ffffff800818b8ec>] lru_add_drain_all+0x4c/0x1b4
>>  #7:  (cpu_hotplug.dep_map){++++++}, at: [<ffffff80080ab8f4>] get_online_cpus+0x3c/0x9c
>
> I think this situation suggests that

[...]

> Somebody is waiting forever with cpu_hotplug.lock held?
> I think that full dmesg with SysRq-t output is appreciated.

As SysRq doesn't work with my serial console, I added calls to show_state()
and show_workqueue_state() to check_hung_task().

Result with current linus/master attached.

Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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