From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f182.google.com (mail-ob0-f182.google.com [209.85.214.182]) by kanga.kvack.org (Postfix) with ESMTP id 915196B0071 for ; Sun, 1 Mar 2015 20:54:27 -0500 (EST) Received: by mail-ob0-f182.google.com with SMTP id nt9so28057520obb.13 for ; Sun, 01 Mar 2015 17:54:27 -0800 (PST) Received: from cnbjrel01.sonyericsson.com (cnbjrel01.sonyericsson.com. [219.141.167.165]) by mx.google.com with ESMTPS id a10si4355382oel.47.2015.03.01.17.54.25 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 01 Mar 2015 17:54:26 -0800 (PST) From: "Wang, Yalin" Date: Mon, 2 Mar 2015 09:53:59 +0800 Subject: RE: [RFC] mm: change mm_advise_free to clear page dirty Message-ID: <35FD53F367049845BC99AC72306C23D10458D6173BE2@CNBJMBX05.corpusers.net> References: <1424765897-27377-1-git-send-email-minchan@kernel.org> <20150224154318.GA14939@dhcp22.suse.cz> <20150225000809.GA6468@blaptop> <35FD53F367049845BC99AC72306C23D10458D6173BDC@CNBJMBX05.corpusers.net> <20150227210233.GA29002@dhcp22.suse.cz> <35FD53F367049845BC99AC72306C23D10458D6173BE0@CNBJMBX05.corpusers.net> <20150228135555.GB25311@blaptop> In-Reply-To: <20150228135555.GB25311@blaptop> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: 'Minchan Kim' Cc: 'Michal Hocko' , Andrew Morton , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Rik van Riel , Johannes Weiner , Mel Gorman , Shaohua Li > -----Original Message----- > From: Minchan Kim [mailto:minchan.kim@gmail.com] On Behalf Of Minchan Kim > Sent: Saturday, February 28, 2015 9:56 PM > To: Wang, Yalin > Cc: 'Michal Hocko'; Andrew Morton; linux-kernel@vger.kernel.org; linux- > mm@kvack.org; Rik van Riel; Johannes Weiner; Mel Gorman; Shaohua Li > Subject: Re: [RFC] mm: change mm_advise_free to clear page dirty >=20 > On Sat, Feb 28, 2015 at 10:11:13AM +0800, Wang, Yalin wrote: > > > -----Original Message----- > > > From: Michal Hocko [mailto:mstsxfx@gmail.com] On Behalf Of Michal Hoc= ko > > > Sent: Saturday, February 28, 2015 5:03 AM > > > To: Wang, Yalin > > > Cc: 'Minchan Kim'; Andrew Morton; linux-kernel@vger.kernel.org; linux= - > > > mm@kvack.org; Rik van Riel; Johannes Weiner; Mel Gorman; Shaohua Li > > > Subject: Re: [RFC] mm: change mm_advise_free to clear page dirty > > > > > > On Fri 27-02-15 11:37:18, Wang, Yalin wrote: > > > > This patch add ClearPageDirty() to clear AnonPage dirty flag, > > > > the Anonpage mapcount must be 1, so that this page is only used by > > > > the current process, not shared by other process like fork(). > > > > if not clear page dirty for this anon page, the page will never be > > > > treated as freeable. > > > > > > Very well spotted! I haven't noticed that during the review. > > > > > > > Signed-off-by: Yalin Wang > > > > --- > > > > mm/madvise.c | 15 +++++---------- > > > > 1 file changed, 5 insertions(+), 10 deletions(-) > > > > > > > > diff --git a/mm/madvise.c b/mm/madvise.c > > > > index 6d0fcb8..257925a 100644 > > > > --- a/mm/madvise.c > > > > +++ b/mm/madvise.c > > > > @@ -297,22 +297,17 @@ static int madvise_free_pte_range(pmd_t *pmd, > > > unsigned long addr, > > > > continue; > > > > > > > > page =3D vm_normal_page(vma, addr, ptent); > > > > - if (!page) > > > > + if (!page || !PageAnon(page) || !trylock_page(page)) > > > > continue; > > > > > > PageAnon check seems to be redundant because we are not allowing > > > MADV_FREE on any !anon private mappings AFAIR. > > I only see this check: > > /* MADV_FREE works for only anon vma at the moment */ > > if (vma->vm_file) > > return -EINVAL; > > > > but for file private map, there are also AnonPage sometimes, do we need > change > > to like this: > > if (vma->vm_flags & VM_SHARED) > > return -EINVAL; >=20 > I couldn't understand your point. In this stage, we intentionally > disabled madvise_free on file mapped area(AFAIRC, some guys tried > it long time ago but it had many issues so dropped). > So, how can file-private mmaped can reach this code? > Could you elaborate it more about that why we need PageAnon check > in here? >=20 I send a new patch: [RFC V2] mm: change mm_advise_free to clear page dirty Please have a look at it. Thanks for your comments! -- 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