From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 3C4536B0038 for ; Tue, 12 Sep 2017 17:12:55 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id f4so11468706wmh.7 for ; Tue, 12 Sep 2017 14:12:55 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id q204sor2845597wmb.91.2017.09.12.14.12.54 for (Google Transport Security); Tue, 12 Sep 2017 14:12:54 -0700 (PDT) Date: Tue, 12 Sep 2017 23:12:50 +0200 From: Alexandru Moise <00moses.alexander00@gmail.com> Subject: Re: [PATCH] mm, hugetlb, soft_offline: save compound page order before page migration Message-ID: <20170912211250.GB16850@gmail.com> References: <20170912204306.GA12053@gmail.com> <20170912135448.341359676c6f8045f4a622f0@linux-foundation.org> <20170912135835.0b48340ead5570e50529f676@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170912135835.0b48340ead5570e50529f676@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, khandual@linux.vnet.ibm.com, mhocko@suse.com, aarcange@redhat.com, minchan@kernel.org, hillf.zj@alibaba-inc.com, shli@fb.com, rppt@linux.vnet.ibm.com, kirill.shutemov@linux.intel.com, mgorman@techsingularity.net, rientjes@google.com, riel@redhat.com, linux-mm@kvack.org On Tue, Sep 12, 2017 at 01:58:35PM -0700, Andrew Morton wrote: > On Tue, 12 Sep 2017 13:54:48 -0700 Andrew Morton wrote: > > > On Tue, 12 Sep 2017 22:43:06 +0200 Alexandru Moise <00moses.alexander00@gmail.com> wrote: > > > > > This fixes a bug in madvise() where if you'd try to soft offline a > > > hugepage via madvise(), while walking the address range you'd end up, > > > using the wrong page offset due to attempting to get the compound > > > order of a former but presently not compound page, due to dissolving > > > the huge page (since c3114a8). > > > > What are the user visible effects of the bug? The wrong page is > > offlined? No offlining occurs? > > This also affects MADV_HWPOISON? No, MADV_HWPOISON is ok because it doesn't dissolve the hugepage, so the page remains a compound page the 2nd loop around. ../Alex -- 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