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Date:   Wed, 28 Aug 2019 21:45:05 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Ingo Molnar <mingo@kernel.org>
cc:     LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        Song Liu <songliubraving@fb.com>,
        Joerg Roedel <jroedel@suse.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Rik van Riel <riel@surriel.com>
Subject: Re: [patch 1/2] x86/mm/pti: Handle unaligned address gracefully in
 pti_clone_pagetable()
In-Reply-To: <20190828185832.GA77809@gmail.com>
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References: <20190828142445.454151604@linutronix.de> <20190828143123.971884723@linutronix.de> <20190828185832.GA77809@gmail.com>
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On Wed, 28 Aug 2019, Ingo Molnar wrote:
> >  		pmd = pmd_offset(pud, addr);
> >  		if (pmd_none(*pmd)) {
> > -			addr += PMD_SIZE;
> > +			WARN_ON_ONCE(addr & PMD_MASK);
> > +			addr = round_up(addr + 1, PMD_SIZE);
> 
> So given that PUD_MASK and PMD_MASK are masking out the *offset*:
> 
>  arch/x86/include/asm/pgtable_64_types.h:#define PMD_MASK	(~(PMD_SIZE - 1))
> 
> Didn't we want something like:
> 
> 			WARN_ON_ONCE(addr & ~PUD_MASK);
> 
> 			WARN_ON_ONCE(addr & ~PMD_MASK);
> 
> to warn about an unaligned 'addr', or am I misreading the intent here?

Bah, right you are...