linux-kernel - Re: [RFC] MIPS: smp: Sleeping func called from start

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Message-ID: <utfmb7mxm6emxditrq7fwalatnhszzcztu4gnqs5mf44umvfwa@k4i7gamaj5mw>
Date: Fri, 2 Aug 2024 12:53:30 +0300
From: Serge Semin <fancer.lancer@...il.com>
To: Jiaxun Yang <jiaxun.yang@...goat.com>
Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
	Thomas Gleixner <tglx@...utronix.de>, Andrew Morton <akpm@...ux-foundation.org>, 
	Arnd Bergmann <arnd@...db.de>, Kelvin Cheung <keguang.zhang@...il.com>, 
	Gregory CLEMENT <gregory.clement@...tlin.com>, Théo Lebrun <theo.lebrun@...tlin.com>, 
	Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>, Tawfik Bayouk <tawfik.bayouk@...ileye.com>, 
	Huacai Chen <chenhuacai@...nel.org>, "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>, 
	linux-kernel@...r.kernel.org
Subject: Re: [RFC] MIPS: smp: Sleeping func called from start_secondary()

Hi Jiaxun

On Fri, Aug 02, 2024 at 05:43:45PM +0800, Jiaxun Yang wrote:
> 
> 
> 在2024年8月2日八月 下午4:45，Serge Semin写道：
> > Hi folks,
> >
> > To debug some another problem I recently enabled the
> > CONFIG_DEBUG_ATOMIC_SLEEP config for my SoC based on the 2xP5600 cores
> > with MIPS GIC as IRQ-controller. That caused the next BUG backtrace
> > started being printed to the system log during the device boot-up:
> 
> Hi Serge,
> 
> Thanks for reporting the problem!
> 
> I actually have a patch lying around somewhere to convert cevt-r4k to use CPUHP
> interface and avoid requesting interrupt on secondary CPUs.
> 
> Will post after getting more platform tests.

Great! Thanks. I'll test it out upon submission.

* Although I doubt that such (presumably) complicated change might be
considered as a backportable fix. But at least it shall fix the problem for the
mainline kernel.

Thanks,
-Serge(y)

> 
> Thanks
> - Jiaxun
> 
> >
> > [    0.118053] BUG: sleeping function called from invalid context at 
> > kernel/locking/mutex.c:283
> > [    0.118062] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 
> > 0, name: swapper/1
> > [    0.118069] preempt_count: 1, expected: 0
> > [    0.118074] RCU nest depth: 0, expected: 0
> > [    0.118078] Preemption disabled at:
> > [    0.118082] [<80105040>] arch_dup_task_struct+0x20/0x118
> > [    0.118116] CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 
> > 6.11.0-rc1-bt1-00312-gca6f9469050c-dirty #2460
> > [    0.118134] Stack : 816d0000 801b89bc 81870000 00000004 a02d0c08 
> > 00000000 84ae7dcc 801b84c0
> > [    0.118167]         00000000 00000002 00000000 00000000 00000000 
> > 00000001 84ae7d70 84aaf200
> > [    0.118195]         00000000 00000000 81115acc 00000000 00000059 
> > 84ae7bec 00000000 00000000
> > [    0.118222]         00000000 ffffffff ffffffea 00000020 816d0000 
> > 00000000 81115acc 00000002
> > [    0.118250]         00000000 04240021 a02d0c08 00000000 00000000 
> > 00000000 30400000 ac24242a
> > [    0.118277]         ...
> > [    0.118286] Call Trace:
> > [    0.118289] [<8010af2c>] show_stack+0x88/0x120
> > [    0.118309] [<80f09dfc>] dump_stack_lvl+0x78/0xb0
> > [    0.118323] [<801778d0>] __might_resched+0x190/0x1f0
> > [    0.118349] [<80f10f80>] mutex_lock+0x20/0x74
> > [    0.118365] [<801c8590>] irq_create_mapping_affinity+0x48/0x104
> > [    0.118390] [<801121ec>] r4k_clockevent_init+0x58/0x38c
> > [    0.118402] [<80116658>] start_secondary+0x34/0x134
> > [    0.118411] [<80f0b1e4>] smp_bootstrap+0x68/0x98
> > [    0.118424] 
> >
> > I managed to investigate the problem a bit and the reason turned out to be
> > in the irq_create_mapping() method eventually invoked in the framework of the
> > secondary CPU start-up procedure. The more detailed calls chain is:
> > start_secondary()
> > +-> mips_clockevent_init()
> >     +-> r4k_clockevent_init()
> >         +-> get_c0_compare_int()
> >             +-> gic_get_c0_compare_int()
> >                 +-> irq_create_mapping()
> >                     +-> irq_create_mapping_affinity()
> >                         +-> mutex_lock()
> >                             +-> might_sleep()
> >                                 +-> might_resched()
> >                                     +-> __might_resched()
> >                                         +-> Print the log above
> >
> > I currently lack of free time for further investigation in an attempt to
> > find a reasonable solution. So here is just a report and a short summary
> > of the problem. Should you have any idea of how to fix the problem I'll be
> > very glad to test it out on a short notice.
> >
> > -Serge(y)
> 
> -- 
> - Jiaxun