Re: [RFC V2 1/6] loongarch/mm: Stop using pte_ERROR()

From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>,
	linux-mm@kvack.org, akpm@linux-foundation.org
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>,
	John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Helge Deller <deller@gmx.de>, Huacai Chen <chenhuacai@kernel.org>,
	WANG Xuerui <kernel@xen0n.name>,
	linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org,
	linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
	linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
	sparclinux@vger.kernel.org, linux-um@lists.infradead.org,
	linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC V2 1/6] loongarch/mm: Stop using pte_ERROR()
Date: Wed, 12 Aug 2026 13:27:54 +0200	[thread overview]
Message-ID: <9a66d741-536e-44ac-b02f-395b5fc8ab6d@kernel.org> (raw)
In-Reply-To: <e0ada89f-26b2-4e82-8273-8ea7b391c147@kernel.org>

On 8/12/26 13:19, David Hildenbrand (Arm) wrote:
> On 8/11/26 06:21, Anshuman Khandual wrote:
>> Directly use pr_err() in __set_fixmap() and drop pte_ERROR() which helps in
>> eventually dropping pte_ERROR() macro across the tree. In this new printing
>> __FILE__ and __LINE__ has been dropped because they are always the same and
>> don't really add any value.
>>
>> Cc: Huacai Chen <chenhuacai@kernel.org>
>> Cc: WANG Xuerui <kernel@xen0n.name>
>> Cc: loongarch@lists.linux.dev
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>>  arch/loongarch/include/asm/pgtable.h | 2 --
>>  arch/loongarch/mm/init.c             | 2 +-
>>  2 files changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
>> index 223528c04d73..a32a8fff70c1 100644
>> --- a/arch/loongarch/include/asm/pgtable.h
>> +++ b/arch/loongarch/include/asm/pgtable.h
>> @@ -128,8 +128,6 @@ struct vm_area_struct;
>>  #define ptep_get(ptep) READ_ONCE(*(ptep))
>>  #define pmdp_get(pmdp) READ_ONCE(*(pmdp))
>>  
>> -#define pte_ERROR(e) \
>> -	pr_err("%s:%d: bad pte %016lx.\n", __FILE__, __LINE__, pte_val(e))
>>  #ifndef __PAGETABLE_PMD_FOLDED
>>  #define pmd_ERROR(e) \
>>  	pr_err("%s:%d: bad pmd %016lx.\n", __FILE__, __LINE__, pmd_val(e))
>> diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
>> index 3407030f3e7a..be9b127daef2 100644
>> --- a/arch/loongarch/mm/init.c
>> +++ b/arch/loongarch/mm/init.c
>> @@ -203,7 +203,7 @@ void __init __set_fixmap(enum fixed_addresses idx,
>>  
>>  	ptep = populate_kernel_pte(addr);
>>  	if (!pte_none(ptep_get(ptep))) {
>> -		pte_ERROR(*ptep);
>> +		pr_err("bad pte %016lx\n", pte_val(*ptep));
>>  		return;
>>  	}
>>  
> 
> Ah, I missed that we want to print actual values, I somehow thought that we
> would be printing pte_none() ...
> 
> Maybe we should just be more verbose while at it?
> 
> pr_err("unexpected set PTE at %ul in __set_fixmap: %016lx\n",
>        addr, pte_val(*ptep));
> 

On second thought, why not simply use ptval_to_str() here as well?

-- 
Cheers,

David