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Subject: Re: [PATCH v3 2/2] mm: remove odd HAVE_PTE_SPECIAL
References: <1523433816-14460-1-git-send-email-ldufour@linux.vnet.ibm.com>
 <1523433816-14460-3-git-send-email-ldufour@linux.vnet.ibm.com>
 <20180411083315.GA23400@dhcp22.suse.cz>
From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Date: Wed, 11 Apr 2018 10:41:23 +0200
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To: Michal Hocko <mhocko@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, Jerome Glisse <jglisse@redhat.com>, aneesh.kumar@linux.vnet.ibm.com, akpm@linux-foundation.org, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, Jonathan Corbet <corbet@lwn.net>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Yoshinori Sato <ysato@users.sourceforge.jp>, Rich Felker <dalias@libc.org>, "David S . Miller" <davem@davemloft.net>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Vineet Gupta <vgupta@synopsys.com>, Palmer Dabbelt <palmer@sifive.com>, Albert Ou <albert@sifive.com>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, David Rientjes <rientjes@google.com>, Robin Murphy <robin.murphy@arm.com>

On 11/04/2018 10:33, Michal Hocko wrote:
> On Wed 11-04-18 10:03:36, Laurent Dufour wrote:
>> @@ -881,7 +876,8 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
>>  
>>  	if (is_zero_pfn(pfn))
>>  		return NULL;
>> -check_pfn:
>> +
>> +check_pfn: __maybe_unused
>>  	if (unlikely(pfn > highest_memmap_pfn)) {
>>  		print_bad_pte(vma, addr, pte, NULL);
>>  		return NULL;
>> @@ -891,7 +887,7 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
>>  	 * NOTE! We still have PageReserved() pages in the page tables.
>>  	 * eg. VDSO mappings can cause them to exist.
>>  	 */
>> -out:
>> +out: __maybe_unused
>>  	return pfn_to_page(pfn);
> 
> Why do we need this ugliness all of the sudden?
Indeed the compiler doesn't complaint but in theory it should since these
labels are not used depending on CONFIG_ARCH_HAS_PTE_SPECIAL.