Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755288AbYG2AvP (ORCPT ); Mon, 28 Jul 2008 20:51:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751914AbYG2Au5 (ORCPT ); Mon, 28 Jul 2008 20:50:57 -0400 Received: from fg-out-1718.google.com ([72.14.220.153]:62768 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755429AbYG2Au4 (ORCPT ); Mon, 28 Jul 2008 20:50:56 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=b5eZ9qQpjr/WG2dUW+1dr1EpO/vX6p+gmssQTEmh06MD4+mCS5MMRJyruaPyVoWkSn sNaLuiinRWYEH+HmFgFbGIsdtho+teVrBmWdVT58juBvtzZ9xew+XLDxIXkiZEU1xSNt kc/UU/reb+g3KVr7XL/ns2hsLkCBIqzbB250s= Date: Tue, 29 Jul 2008 04:51:05 +0400 From: Alexey Dobriyan To: Linus Torvalds Cc: Johannes Weiner , akpm@linuxfoundation.org, torvalds@linuxfoundation.org, npiggin@suse.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: do not overrun page table ranges in gup Message-ID: <20080729005105.GA15046@martell.zuzino.mipt.ru> References: <20080728184947.GA5041@martell.zuzino.mipt.ru> <20080728185316.GA19479@martell.zuzino.mipt.ru> <87y73l5zlj.fsf_-_@saeurebad.de> <87tze95yrk.fsf@saeurebad.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1348 Lines: 44 On Mon, Jul 28, 2008 at 05:39:18PM -0700, Linus Torvalds wrote: > > > On Mon, 28 Jul 2008, Linus Torvalds wrote: > > > > So no, the right fix would be to align 'start' first, which means that > > everything else (including 'end') will be page-aligned. Aligning just one > > or the other is very very wrong. > > Does this work? > > Not pretty, but it stands _some_ chance of being correct. vmsplice01 doesn't crash now. > --- a/arch/x86/mm/gup.c > +++ b/arch/x86/mm/gup.c > @@ -223,14 +223,17 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, > struct page **pages) > { > struct mm_struct *mm = current->mm; > - unsigned long end = start + (nr_pages << PAGE_SHIFT); > - unsigned long addr = start; > + unsigned long addr, len, end; > unsigned long next; > pgd_t *pgdp; > int nr = 0; > > + start &= PAGE_MASK; > + addr = start; > + len = (unsigned long) nr_pages << PAGE_SHIFT; > + end = start + len; > if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, > - start, nr_pages*PAGE_SIZE))) > + start, len))) > goto slow_irqon; > > /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/