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Date: Tue, 14 Nov 2017 23:21:02 +0300
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Nicholas Piggin <npiggin@gmail.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCHv2 1/2] x86/mm: Do not allow non-MAP_FIXED mapping across
 DEFAULT_MAP_WINDOW border
Message-ID: <20171114202102.crpgiwgv2lu5aboq@node.shutemov.name>
References: <20171114134322.40321-1-kirill.shutemov@linux.intel.com>
 <alpine.DEB.2.20.1711141630210.2044@nanos>
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On Tue, Nov 14, 2017 at 05:01:50PM +0100, Thomas Gleixner wrote:
> @@ -198,11 +199,14 @@ arch_get_unmapped_area_topdown(struct fi
>  	/* requesting a specific address */
>  	if (addr) {
>  		addr = PAGE_ALIGN(addr);
> +		if (!mmap_address_hint_valid(addr, len))
> +			goto get_unmapped_area;
> +

Here and in hugetlb_get_unmapped_area(), we should align the addr after
the check, not before. Otherwise the alignment itself can bring us over
the borderline as we align up.

-- 
 Kirill A. Shutemov