From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752134AbdK0Ldq (ORCPT ); Mon, 27 Nov 2017 06:33:46 -0500 Received: from mx2.suse.de ([195.135.220.15]:42482 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751451AbdK0Ldp (ORCPT ); Mon, 27 Nov 2017 06:33:45 -0500 Date: Mon, 27 Nov 2017 12:33:41 +0100 From: Michal Hocko To: JianKang Chen Cc: akpm@linux-foundation.org, mgorman@techsingularity.net, hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xieyisheng1@huawei.com, guohanjun@huawei.com, wangkefeng.wang@huawei.com Subject: Re: [PATCH resend] mm/page_alloc: fix comment is __get_free_pages Message-ID: <20171127113341.ldx32qvexqe2224d@dhcp22.suse.cz> References: <1511780964-64864-1-git-send-email-chenjiankang1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1511780964-64864-1-git-send-email-chenjiankang1@huawei.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 27-11-17 19:09:24, JianKang Chen wrote: > From: Jiankang Chen > > __get_free_pages will return an virtual address, > but it is not just 32-bit address, for example a 64-bit system. > And this comment really confuse new bigenner of mm. s@bigenner@beginner@ Anyway, do we really need a bug on for this? Has this actually caught any wrong usage? VM_BUG_ON tends to be enabled these days AFAIK and panicking the kernel seems like an over-reaction. If there is a real risk then why don't we simply mask __GFP_HIGHMEM off when calling alloc_pages? > reported-by: Hanjun Guo > Signed-off-by: Jiankang Chen > --- > mm/page_alloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 77e4d3c..5a7c432 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4240,7 +4240,7 @@ unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order) > struct page *page; > > /* > - * __get_free_pages() returns a 32-bit address, which cannot represent > + * __get_free_pages() returns a virtual address, which cannot represent > * a highmem page > */ > VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0); > -- > 1.7.12.4 > -- Michal Hocko SUSE Labs