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From: Song Liu <songliubraving@fb.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Kernel Team <Kernel-team@fb.com>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	Joerg Roedel <jroedel@suse.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH] x86/mm/pti: in pti_clone_pgtable() don't increase addr by PUD_SIZE
Date: Tue, 20 Aug 2019 13:21:34 +0000	[thread overview]
Message-ID: <44EA504D-2388-49EF-A807-B9712903B146@fb.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1908201315450.2223@nanos.tec.linutronix.de>



> On Aug 20, 2019, at 4:16 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> 
> On Tue, 20 Aug 2019, Peter Zijlstra wrote:
>> What that code wants to do is skip to the end of the pud, a pmd_size
>> increase will not do that. And right below this, there's a second
>> instance of this exact pattern.
>> 
>> Did I get the below right?
>> 
>> ---
>> diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
>> index b196524759ec..32b20b3cb227 100644
>> --- a/arch/x86/mm/pti.c
>> +++ b/arch/x86/mm/pti.c
>> @@ -330,12 +330,14 @@ pti_clone_pgtable(unsigned long start, unsigned long end,
>> 
>> 		pud = pud_offset(p4d, addr);
>> 		if (pud_none(*pud)) {
>> +			addr &= PUD_MASK;
>> 			addr += PUD_SIZE;
> 
> 			round_up(addr, PUD_SIZE);

I guess we need "round_up(addr + PMD_SIZE, PUD_SIZE)". 

Thanks,
Song

> 
> perhaps?
> 
>> 			continue;
>> 		}
>> 
>> 		pmd = pmd_offset(pud, addr);
>> 		if (pmd_none(*pmd)) {
>> +			addr &= PMD_MASK;
>> 			addr += PMD_SIZE;
>> 			continue;
>> 		}
>> 


  reply	other threads:[~2019-08-20 13:21 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-20  7:51 [PATCH] x86/mm/pti: in pti_clone_pgtable() don't increase addr by PUD_SIZE Song Liu
2019-08-20  9:12 ` Thomas Gleixner
2019-08-20  9:12   ` Thomas Gleixner
2019-08-20 13:17   ` Song Liu
2019-08-20 10:00 ` Peter Zijlstra
2019-08-20 11:16   ` Thomas Gleixner
2019-08-20 11:16     ` Thomas Gleixner
2019-08-20 13:21     ` Song Liu [this message]
2019-08-20 13:39       ` Thomas Gleixner
2019-08-20 13:39         ` Thomas Gleixner
2019-08-20 13:55       ` Rik van Riel
2019-08-20 14:00         ` Song Liu
2019-08-20 16:56           ` [PATCH v2] " Rik van Riel
2019-08-20 16:56             ` Rik van Riel
2019-08-20 13:21     ` [PATCH] " Rik van Riel
2019-08-20 13:19   ` Song Liu
2019-08-20 13:57 ` Dave Hansen
2019-08-20 14:14   ` Song Liu
2019-08-20 14:18     ` Dave Hansen
2019-08-20 16:05       ` Song Liu
2019-08-20 16:38         ` Song Liu

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