From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id DBC52280246 for ; Tue, 14 Nov 2017 17:27:21 -0500 (EST) Received: by mail-wr0-f198.google.com with SMTP id o88so11561155wrb.18 for ; Tue, 14 Nov 2017 14:27:21 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id j9sor12143781edf.30.2017.11.14.14.27.20 for (Google Transport Security); Tue, 14 Nov 2017 14:27:20 -0800 (PST) Date: Wed, 15 Nov 2017 01:27:18 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCHv2 1/2] x86/mm: Do not allow non-MAP_FIXED mapping across DEFAULT_MAP_WINDOW border Message-ID: <20171114222718.76w4lmclf6wasbl3@node.shutemov.name> References: <20171114134322.40321-1-kirill.shutemov@linux.intel.com> <20171114202102.crpgiwgv2lu5aboq@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner Cc: "Kirill A. Shutemov" , Ingo Molnar , x86@kernel.org, "H. Peter Anvin" , Linus Torvalds , Andy Lutomirski , Nicholas Piggin , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Tue, Nov 14, 2017 at 09:54:52PM +0100, Thomas Gleixner wrote: > On Tue, 14 Nov 2017, Kirill A. Shutemov wrote: > > > 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. > > Hmm, then I wonder whether the next check against vm_start_gap() which > checks against the aligned address is correct: > > addr = PAGE_ALIGN(addr); > vma = find_vma(mm, addr); > > if (end - len >= addr && > (!vma || addr + len <= vm_start_gap(vma))) > return addr; I think the check is correct. The check is against resulting addresses that end up in vm_start/vm_end. In our case we want to figure out what user asked for. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org