From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f181.google.com (mail-io0-f181.google.com [209.85.223.181]) by kanga.kvack.org (Postfix) with ESMTP id E98046B0038 for ; Tue, 27 Oct 2015 04:10:41 -0400 (EDT) Received: by iofz202 with SMTP id z202so212328451iof.2 for ; Tue, 27 Oct 2015 01:10:41 -0700 (PDT) Received: from mail-pa0-x234.google.com (mail-pa0-x234.google.com. [2607:f8b0:400e:c03::234]) by mx.google.com with ESMTPS id y138si28251517iod.172.2015.10.27.01.10.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Oct 2015 01:10:41 -0700 (PDT) Received: by padhk11 with SMTP id hk11so215539938pad.1 for ; Tue, 27 Oct 2015 01:10:41 -0700 (PDT) Date: Tue, 27 Oct 2015 17:10:59 +0900 From: Minchan Kim Subject: Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE Message-ID: <20151027081059.GE26803@bbox> References: <1445236307-895-1-git-send-email-minchan@kernel.org> <1445236307-895-5-git-send-email-minchan@kernel.org> <20151027070903.GD26803@bbox> <32537EDE-3EE6-4C44-B820-5BCAF7A5D535@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <32537EDE-3EE6-4C44-B820-5BCAF7A5D535@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: yalin wang 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 Tue, Oct 27, 2015 at 03:39:16PM +0800, yalin wang wrote: > > > On Oct 27, 2015, at 15:09, Minchan Kim wrote: > > > > Hello Yalin, > > > > Sorry for missing you in Cc list. > > IIRC, mails to send your previous mail address(Yalin.Wang@sonymobile.com) > > were returned. > > > > You added comment bottom line so I'm not sure what PageDirty you meant. > > > >> 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 > > > > 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. > > > > Am I missing something from you question? > > If so, could you show exact scenario I am missing? > > > > 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 > 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 = 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 dona??t 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 ? Your understanding is correct. I will fix it in next spin. > > By the way, please change my mail address to yalin.wang2010@gmail.com in CC list . > Thanks a lot. :) Thanks for the review! > -- 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