linux-kernel - Re: build failure of next-20220817 for amdgpu due to 7bc913085765 ("drm/amdkfd: Try to schedule bottom half on same core")

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Message-ID: <df284479-9981-9983-7775-81d7d7875dac@infradead.org>
Date:   Thu, 18 Aug 2022 12:34:46 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Sudip Mukherjee <sudipm.mukherjee@...il.com>,
        Felix Kuehling <Felix.Kuehling@....com>,
        Alex Deucher <alexander.deucher@....com>
Cc:     Alex Deucher <alexdeucher@...il.com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        linux-next <linux-next@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        amd-gfx mailing list <amd-gfx@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: build failure of next-20220817 for amdgpu due to 7bc913085765
 ("drm/amdkfd: Try to schedule bottom half on same core")

Hi--

On 8/18/22 12:15, Sudip Mukherjee wrote:
> On Thu, Aug 18, 2022 at 4:10 PM Randy Dunlap <rdunlap@...radead.org> wrote:
>>
>>
>>
>> On 8/18/22 03:43, Sudip Mukherjee wrote:
>>> On Thu, Aug 18, 2022 at 3:09 AM Randy Dunlap <rdunlap@...radead.org> wrote:
>>>>
>>>>
>>>>
>>>> On 8/17/22 19:01, Alex Deucher wrote:
>>>>> On Wed, Aug 17, 2022 at 6:03 PM Sudip Mukherjee (Codethink)
>>>>> <sudipm.mukherjee@...il.com> wrote:
>>>>>>
>>>>>> Hi All,
>>>>>>
>>>>>> Not sure if it has been reported, build of next-20220817 fails with the
>>>>>> error:
>>>>>>
>>>>>> ERROR: modpost: "cpu_smallcore_map" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
>>>>>>
>>>>>> Trying to do a git bisect to find out the offending commit.
>>>>>>
>>>>>
>>>>> Thanks.  I don't see that symbol in the driver at all.  Not sure where
>>>>> it is coming from.
>>>>>
>>>>
>>>> It's powerpc only.
>>>>
>>>> Sudip, is it non-CONFIG_SMP by any chance?
>>>
>>> Ohhh.. really sorry for the incomplete report. I should not try to
>>> mail while travelling.
>>>
>>> The error is seen with powerpc allmodconfig and it has CONFIG_SMP=y.
>>
>> OK, I see that also, but it doesn't make any sense (to me).
>>
>> I did 'objdump' on the code file (amdgpu.o) and it's listed as
>> undefined but there are no code references to it.
> 
> cpu_smt_mask() is called by drivers/gpu/drm/amd/amdkfd/kfd_device.c.
> and cpu_smt_mask() is an inline function in
> arch/powerpc/include/asm/smp.h which is doing "return
> per_cpu(cpu_smallcore_map, cpu);"
> 
> So, the offending commit is 7bc913085765 ("drm/amdkfd: Try to schedule
> bottom half on same core").

Thanks for digging that up.

It just needs to have that symbol exported I think.
This builds cleanly now.
I can submit it or one of the AMD gfx developers can do so.


---
 arch/powerpc/kernel/smp.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -86,6 +86,7 @@ DEFINE_PER_CPU(cpumask_var_t, cpu_core_m
 static DEFINE_PER_CPU(cpumask_var_t, cpu_coregroup_map);
 
 EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
+EXPORT_PER_CPU_SYMBOL(cpu_smallcore_map);
 EXPORT_PER_CPU_SYMBOL(cpu_l2_cache_map);
 EXPORT_PER_CPU_SYMBOL(cpu_core_map);
 EXPORT_SYMBOL_GPL(has_big_cores);


-- 
~Randy