From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f174.google.com (mail-io0-f174.google.com [209.85.223.174]) by kanga.kvack.org (Postfix) with ESMTP id 119AD6B0038 for ; Tue, 27 Oct 2015 03:39:26 -0400 (EDT) Received: by iodd200 with SMTP id d200so49232473iod.0 for ; Tue, 27 Oct 2015 00:39:25 -0700 (PDT) Received: from mail-pa0-x22e.google.com (mail-pa0-x22e.google.com. [2607:f8b0:400e:c03::22e]) by mx.google.com with ESMTPS id c88si8673315iod.69.2015.10.27.00.39.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Oct 2015 00:39:25 -0700 (PDT) Received: by padhk11 with SMTP id hk11so214700071pad.1 for ; Tue, 27 Oct 2015 00:39:25 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.0 \(3094\)) Subject: Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE From: yalin wang In-Reply-To: <20151027070903.GD26803@bbox> Date: Tue, 27 Oct 2015 15:39:16 +0800 Content-Transfer-Encoding: quoted-printable Message-Id: <32537EDE-3EE6-4C44-B820-5BCAF7A5D535@gmail.com> References: <1445236307-895-1-git-send-email-minchan@kernel.org> <1445236307-895-5-git-send-email-minchan@kernel.org> <20151027070903.GD26803@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Hugh Dickins , Andrew Morton , "open list:MEMORY MANAGEMENT" , lkml , Rik van Riel , Mel Gorman , Michal Hocko , Johannes Weiner , "Kirill A. Shutemov" , Vlastimil Babka > On Oct 27, 2015, at 15:09, Minchan Kim wrote: >=20 > Hello Yalin, >=20 > Sorry for missing you in Cc list. > IIRC, mails to send your previous mail = address(Yalin.Wang@sonymobile.com) > were returned. >=20 > You added comment bottom line so I'm not sure what PageDirty you = meant. >=20 >> it is wrong here if you only check PageDirty() to decide if the page = is freezable or not . >> The Anon page are shared by multiple process, _mapcount > 1 , >> so you must check all pt_dirty bit during page_referenced() function, >> see this mail thread: >> http://ns1.ske-art.com/lists/kernel/msg1934021.html >=20 > If one of pte among process sharing the page was dirty, the dirtiness = should > be propagated from pte to PG_dirty by try_to_unmap_one. > IOW, if the page doesn't have PG_dirty flag, it means all of process = did > MADV_FREE. >=20 > Am I missing something from you question? > If so, could you show exact scenario I am missing? >=20 > Thanks for the interest. oh, yeah , that is right , i miss that , pte_dirty will propagate to = PG_dirty , so that is correct . Generic to say this patch move set_page_dirty() from add_to_swap() to=20 try_to_unmap(), i think can change a little about this patch: @@ -1476,6 +1446,8 @@ static int try_to_unmap_one(struct page *page, = struct vm_area_struct *vma, ret =3D SWAP_FAIL; goto out_unmap; } + if (!PageDirty(page)) + SetPageDirty(page); if (list_empty(&mm->mmlist)) { spin_lock(&mmlist_lock); if (list_empty(&mm->mmlist)) i think this 2 lines can be removed , since pte_dirty have propagated to set_page_dirty() , we don=E2=80=99t = need this line here , otherwise you will always dirty a AnonPage, even it is clean, then we will page out this clean page to swap partition one more , this = is not needed. am i understanding correctly ? By the way, please change my mail address to yalin.wang2010@gmail.com in = CC list . Thanks a lot. :)=20 -- 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