Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To:     Christophe Leroy <christophe.leroy@c-s.fr>,
        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
Subject: Re: [PATCH v1 02/27] powerpc/mm: don't BUG in add_huge_page_size()
In-Reply-To: <02e312b13129a9bf96f0cd4a30b1802be0644900.1553076180.git.christophe.leroy@c-s.fr>
References: <cover.1553076180.git.christophe.leroy@c-s.fr> <02e312b13129a9bf96f0cd4a30b1802be0644900.1553076180.git.christophe.leroy@c-s.fr>
Date:   Thu, 11 Apr 2019 11:11:13 +0530
MIME-Version: 1.0
Content-Type: text/plain
Message-Id: <87o95d3xqe.fsf@linux.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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?


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