From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f175.google.com (mail-wi0-f175.google.com [209.85.212.175]) by kanga.kvack.org (Postfix) with ESMTP id 61C4A6B0038 for ; Tue, 16 Jun 2015 02:33:53 -0400 (EDT) Received: by wigg3 with SMTP id g3so98711458wig.1 for ; Mon, 15 Jun 2015 23:33:52 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id o6si22324645wiy.112.2015.06.15.23.33.51 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 15 Jun 2015 23:33:51 -0700 (PDT) Date: Tue, 16 Jun 2015 08:33:46 +0200 From: Michal Hocko Subject: Re: Possible broken MM code in dell-laptop.c? Message-ID: <20150616063346.GA24296@dhcp22.suse.cz> References: <201506141105.07171@pali> <20150615211816.GC16138@dhcp22.suse.cz> <201506152327.59907@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <201506152327.59907@pali> Sender: owner-linux-mm@kvack.org List-ID: To: Pali =?iso-8859-1?Q?Roh=E1r?= Cc: Hans de Goede , Darren Hart , Ben Skeggs , Stuart Hayes , Matthew Garrett , Andrew Morton , platform-driver-x86@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Mon 15-06-15 23:27:59, Pali Rohar wrote: > On Monday 15 June 2015 23:18:16 Michal Hocko wrote: > > On Sun 14-06-15 11:05:07, Pali Rohar wrote: > > > Hello, > > > > > > in drivers/platform/x86/dell-laptop.c is this part of code: > > > > > > static int __init dell_init(void) > > > { > > > ... > > > > > > /* > > > > > > * Allocate buffer below 4GB for SMI data--only 32-bit physical > > > addr * is passed to SMI handler. > > > */ > > > > > > bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32); > > > > [...] > > > > > buffer = page_address(bufferpage); > > > > [...] > > > > > fail_rfkill: > > > free_page((unsigned long)bufferpage); > > > > This one should be __free_page because it consumes struct page* and > > it is the proper counter part for alloc_page. free_page, just to > > make it confusing, consumes an address which has to be translated to > > a struct page. > > > > I have no idea why the API has been done this way and yeah, it is > > really confusing. > > > > [...] > > > > > static void __exit dell_exit(void) > > > { > > > ... > > > > > > free_page((unsigned long)buffer); > > So both, either: > > free_page((unsigned long)buffer); > > or > > __free_page(bufferpage); > > is correct? Yes. Although I would use __free_page variant as both seem to be globally visible. -- Michal Hocko SUSE Labs -- 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