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Subject: Re: [PATCH v1 02/27] powerpc/mm: don't BUG in add_huge_page_size()
To:     "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>
Cc:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
References: <cover.1553076180.git.christophe.leroy@c-s.fr>
 <02e312b13129a9bf96f0cd4a30b1802be0644900.1553076180.git.christophe.leroy@c-s.fr>
 <87o95d3xqe.fsf@linux.ibm.com>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Message-ID: <2025a657-da62-ffd3-6c77-b93f677704cc@c-s.fr>
Date:   Wed, 24 Apr 2019 16:09:43 +0200
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Le 11/04/2019 à 07:41, Aneesh Kumar K.V a écrit :
> Christophe Leroy <christophe.leroy@c-s.fr> writes:
> 
>> No reason to BUG() in add_huge_page_size(). Just WARN and
>> reject the add.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>>   arch/powerpc/mm/hugetlbpage.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
>> index 9e732bb2c84a..cf2978e235f3 100644
>> --- a/arch/powerpc/mm/hugetlbpage.c
>> +++ b/arch/powerpc/mm/hugetlbpage.c
>> @@ -634,7 +634,8 @@ static int __init add_huge_page_size(unsigned long long size)
>>   	}
>>   #endif
>>   
>> -	BUG_ON(mmu_psize_defs[mmu_psize].shift != shift);
>> +	if (WARN_ON(mmu_psize_defs[mmu_psize].shift != shift))
>> +		return -EINVAL;
> 
> Same here. There are not catching runtime errors. We should never find
> that true. This is to catch mistakes during development changes. Switch
> to VM_BUG_ON?

Ok, I'll switch to VM_BUG_ON()

Christophe

> 
> 
>>   
>>   	/* Return if huge page size has already been setup */
>>   	if (size_to_hstate(size))
>> -- 
>> 2.13.3