Re: [PATCH v5 17/17] powerpc/32s: Enable CONFIG_VMAP_STACK

From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Paul Mackerras <paulus@samba.org>,
	linuxppc-dev@lists.ozlabs.org, dja@axtens.net
Subject: Re: [PATCH v5 17/17] powerpc/32s: Enable CONFIG_VMAP_STACK
Date: Fri, 7 Feb 2020 17:16:22 +0000	[thread overview]
Message-ID: <05cd3886-7a70-3a6c-c7e6-999a5f829ad9@c-s.fr> (raw)
In-Reply-To: <d6158967-fde3-1a87-44b6-07638bd2b5b0@roeck-us.net>

On 02/07/2020 01:44 PM, Guenter Roeck wrote:
> On 2/7/20 5:29 AM, Christophe Leroy wrote:
>>
>>
>> On 02/07/2020 01:08 PM, Guenter Roeck wrote:
>>> On 2/7/20 12:28 AM, Christophe Leroy wrote:
>>>>
>>>>
>>>> On 02/07/2020 06:13 AM, Christophe Leroy wrote:
>>>>>
>>>>>
>>>>> Le 06/02/2020 à 21:31, Guenter Roeck a écrit :
>>>>>> On Sat, Dec 21, 2019 at 08:32:38AM +0000, Christophe Leroy wrote:
>>>>>>> A few changes to retrieve DAR and DSISR from struct regs
>>>>>>> instead of retrieving them directly, as they may have
>>>>>>> changed due to a TLB miss.
>>>>>>>
>>>>>>> Also modifies hash_page() and friends to work with virtual
>>>>>>> data addresses instead of physical ones. Same on load_up_fpu()
>>>>>>> and load_up_altivec().
>>>>>>>
>>>>>>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>>>>>>
>>>>>> This patch results in qemu boot failures (mac99 with 
>>>>>> pmac32_defconfig).
>>>>>> Images fail silently; there is no console output. Reverting the patch
>>>>>> fixes the problem. Bisect log is attached below.
>>>>>>
>>>>>> Assuming this was tested on real hardware, am I correct to assume 
>>>>>> that qemu
>>>>>> for ppc32 (more specifically, qemu's mac99 and g3beige machines) 
>>>>>> no longer
>>>>>> works with the upstream kernel ?
>>>>>
>>>>> Before submitting the series, I successfully tested:
>>>>> - Real HW with powerpc 8xx
>>>>> - Real HW with powerpc 832x
>>>>> - Qemu's mac99
>>>>>
>>>>> I'll re-check the upstream kernel.
>>>>>
>>>>
>>>> This is still working for me with the upstream kernel:
>>>>
>>>
>>> Interesting. What is your kernel configuration, your qemu version, and
>>> your qemu command line ?
>>
>> Config is pmac32_defconfig + CONFIG_DEVTMPFS (But kernel also boots 
>> without CONFIG_DEVTMPFS)
>>
>> QEMU emulator version 2.11.2
>>
>> qemu-system-ppc -kernel vmlinux -M mac99 -initrd rootfs.cpio.gz -s -m 
>> 1024
>>
>> Works with both GCC 5.5 and GCC 8.1
>>
> Actually, the problem is that I have locking selftest options enabled
> in my tests. Everything works if I disable those. The "culprit" seems
> to be CONFIG_PROVE_LOCKING. Can you retest with CONFIG_PROVE_LOCKING=y ?
> 

With CONFIG_PROVE_LOCKING, I get a deadlock after:

[...]
Kernel virtual memory layout:
   * 0xffbcf000..0xfffff000  : fixmap
   * 0xff400000..0xff800000  : highmem PTEs
   * 0xfeb36000..0xff400000  : early ioremap
   * 0xf1000000..0xfeb36000  : vmalloc & ioremap
SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
Running RCU self tests
NR_IRQS: 512, nr_irqs: 512, preallocated irqs: 16
mpic: Resetting
mpic: Setting up MPIC " MPIC 1   " version 1.2 at 80040000, max 1 CPUs
mpic: ISU size: 64, shift: 6, mask: 3f
mpic: Initializing for 64 sources
GMT Delta read from XPRAM: 0 minutes, DST: on
time_init: decrementer frequency = 100.000000 MHz
time_init: processor frequency   = 900.000000 MHz
clocksource: timebase: mask: 0xffffffffffffffff max_cycles: 
0x171024e7e0, max_idle_ns: 440795205315 ns
clocksource: timebase mult[a000000] shift[24] registered
clockevent: decrementer mult[1999999a] shift[32] cpu[0]
Console: colour dummy device 80x25
Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar

Please test the patch I'll send out in a few minutes.

Thanks
Christophe