linux-kernel - Re: [PATCH v3 RESEND 2/2] x86/mm/KASLR: Fix the size of vmemmap section

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Message-ID: <20190429131612.y7ee2hbujeondcko@kshutemo-mobl1>
Date:   Mon, 29 Apr 2019 16:16:12 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Baoquan He <bhe@...hat.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, tglx@...utronix.de,
        mingo@...nel.org, bp@...en8.de, hpa@...or.com,
        kirill.shutemov@...ux.intel.com, keescook@...omium.org,
        peterz@...radead.org, thgarnie@...gle.com,
        herbert@...dor.apana.org.au, mike.travis@....com,
        frank.ramsay@....com, yamada.masahiro@...ionext.com
Subject: Re: [PATCH v3 RESEND 2/2] x86/mm/KASLR: Fix the size of vmemmap
 section

On Mon, Apr 29, 2019 at 04:12:46PM +0800, Baoquan He wrote:
> > > +	 * Calculate how many TB vmemmap region needs, and aligned to
> > > +	 * 1TB boundary.
> > > +	 */
> > > +	vmemmap_size = (kaslr_regions[0].size_tb << (TB_SHIFT - PAGE_SHIFT)) *
> > > +		sizeof(struct page);
> > 
> > Hm. Don't we need to take into account alignment requirements for struct
> > page here? I'm worried about some exotic debug kernel config where
> > sizeof(struct page) doesn't satify __alignof__(struct page).
> 
> I know sizeof(struct page) has handled its own struct alignment and
> padding.

I didn't realize that. Sorry for the noise.

Acked-by: Kirill A. Shutemov <kirill@...ux.intel.com>

-- 
 Kirill A. Shutemov