From: Rik van Riel <riel@fb.com>
To: Song Liu <songliubraving@fb.com>, 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 13:55:57 +0000 [thread overview]
Message-ID: <d887e9e228440097b666bcd316aabc9827a4b01e.camel@fb.com> (raw)
In-Reply-To: <44EA504D-2388-49EF-A807-B9712903B146@fb.com>
On Tue, 2019-08-20 at 09:21 -0400, Song Liu wrote:
> > 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)".
What does that do if start is less than PMD_SIZE
away from the next PUD_SIZE boundary?
How about: round_up(addr + 1, PUD_SIZE) ?
next prev parent reply other threads:[~2019-08-20 13:56 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 7:51 Song Liu
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 13:21 ` Song Liu
2019-08-20 13:39 ` Thomas Gleixner
2019-08-20 13:55 ` Rik van Riel [this message]
2019-08-20 14:00 ` Song Liu
2019-08-20 16:56 ` [PATCH v2] " 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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