Re: [PATCH 03/13] mm: Add generic p?d_large() macros

From: "Liang, Kan" <kan.liang@linux.intel.com>
To: Steven Price <steven.price@arm.com>,
	Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, "Arnd Bergmann" <arnd@arndb.de>,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	kirill@shutemov.name, "Dave Hansen" <dave.hansen@linux.intel.com>,
	"Will Deacon" <will.deacon@arm.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Andy Lutomirski" <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"James Morse" <james.morse@arm.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 03/13] mm: Add generic p?d_large() macros
Date: Mon, 18 Feb 2019 22:44:10 -0500	[thread overview]
Message-ID: <8a74c111-b099-8d18-5fb0-422909a1367a@linux.intel.com> (raw)
In-Reply-To: <aad21496-a86b-ca91-70b7-0c23ea6fefd3@arm.com>

On 2/18/2019 9:19 AM, Steven Price wrote:
> On 18/02/2019 11:31, Peter Zijlstra wrote:
>> On Fri, Feb 15, 2019 at 05:02:24PM +0000, Steven Price wrote:
>>> From: James Morse <james.morse@arm.com>
>>>
>>> Exposing the pud/pgd levels of the page tables to walk_page_range() means
>>> we may come across the exotic large mappings that come with large areas
>>> of contiguous memory (such as the kernel's linear map).
>>>
>>> For architectures that don't provide p?d_large() macros, provided a
>>> does nothing default.
>>
>> Kan was going to fix that for all archs I think..
>

Yes, I'm still working on a generic function to retrieve page size.
The generic p?d_large() issue has been fixed. However, I found that the 
pgd_page() is not generic either. I'm still working on it.
I will update you on the other thread when all issues are fixed.

> The latest series I can find from Kan is still x86 specific. I'm happy
> to rebase onto something else if Kan has an implementation already
> (please point me in the right direction). Otherwise Kan is obviously
> free to base on these changes.
>

My implementation is similar as yours. I'm happy to re-base on your changes.

Could you please also add a generic p4d_large()?

Thanks,
Kan

> Steve
> 
>> See:
>>
>>    http://lkml.kernel.org/r/20190204105409.GA17550@hirez.programming.kicks-ass.net
>>
>>> Signed-off-by: James Morse <james.morse@arm.com>
>>> Signed-off-by: Steven Price <steven.price@arm.com>
>>> ---
>>>   include/asm-generic/pgtable.h | 10 ++++++++++
>>>   1 file changed, 10 insertions(+)
>>>
>>> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
>>> index 05e61e6c843f..7630d663cd51 100644
>>> --- a/include/asm-generic/pgtable.h
>>> +++ b/include/asm-generic/pgtable.h
>>> @@ -1186,4 +1186,14 @@ static inline bool arch_has_pfn_modify_check(void)
>>>   #define mm_pmd_folded(mm)	__is_defined(__PAGETABLE_PMD_FOLDED)
>>>   #endif
>>>   
>>> +#ifndef pgd_large
>>> +#define pgd_large(x)	0
>>> +#endif
>>> +#ifndef pud_large
>>> +#define pud_large(x)	0
>>> +#endif
>>> +#ifndef pmd_large
>>> +#define pmd_large(x)	0
>>> +#endif
>>> +
>>>   #endif /* _ASM_GENERIC_PGTABLE_H */
>>> -- 
>>> 2.20.1
>>>
>>
>> _______________________________________________
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>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
> 