From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756262AbbCCD7X (ORCPT ); Mon, 2 Mar 2015 22:59:23 -0500 Received: from cnbjrel02.sonyericsson.com ([219.141.167.166]:15390 "EHLO cnbjrel02.sonyericsson.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754615AbbCCD7V convert rfc822-to-8bit (ORCPT ); Mon, 2 Mar 2015 22:59:21 -0500 From: "Wang, Yalin" 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'" , Hugh Dickins , Cyrill Gorcunov Date: Tue, 3 Mar 2015 11:59:17 +0800 Subject: RE: [RFC V3] mm: change mm_advise_free to clear page dirty Thread-Topic: [RFC V3] mm: change mm_advise_free to clear page dirty Thread-Index: AdBVYcsURYhggOtyR4Ojn8J4qhyo1wAA7b4w Message-ID: <35FD53F367049845BC99AC72306C23D10458D6173BE8@CNBJMBX05.corpusers.net> References: <20150303032537.GA25015@blaptop> In-Reply-To: <20150303032537.GA25015@blaptop> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Minchan Kim [mailto:minchan.kim@gmail.com] On Behalf Of Minchan Kim > Sent: Tuesday, March 03, 2015 11:26 AM > 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'; Hugh Dickins; Cyrill Gorcunov > Subject: Re: [RFC V3] mm: change mm_advise_free to clear page dirty > > Could you separte this patch in this patchset thread? > It's tackling differnt problem. > > As well, I had a question to previous thread about why shared page > has a problem now but you didn't answer and send a new patchset. > It makes reviewers/maintainer time waste/confuse. Please, don't > hurry to send a code. Before that, resolve reviewers's comments. > > On Tue, Mar 03, 2015 at 10:06:40AM +0800, Wang, Yalin wrote: > > This patch add ClearPageDirty() to clear AnonPage dirty flag, > > if not clear page dirty for this anon page, the page will never be > > treated as freeable. We also make sure the shared AnonPage is not > > freeable, we implement it by dirty all copyed AnonPage pte, > > so that make sure the Anonpage will not become freeable, unless > > all process which shared this page call madvise_free syscall. > > Please, spend more time to make description clear. I really doubt > who understand this description without code inspection. :( > Of course, I'm not a person to write description clear like native > , either but just I'm sure I spend a more time to write description > rather than coding, at least. :) > I see, I will send another mail for file private map pages. Sorry for my English expressions. I think your solution is ok, Your patch will make sure the anonpage pte will always be dirty. I add some comments for your patch: > --- > mm/madvise.c | 1 - > mm/memory.c | 9 +++++++-- > mm/rmap.c | 2 +- > mm/vmscan.c | 3 +-- > 4 files changed, 9 insertions(+), 6 deletions(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 6d0fcb8..d64200e 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -309,7 +309,6 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned > long addr, > continue; > } > > - ClearPageDirty(page); > unlock_page(page); > } > > diff --git a/mm/memory.c b/mm/memory.c > index 8ae52c9..2f45e77 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2460,9 +2460,14 @@ static int do_swap_page(struct mm_struct *mm, struct > vm_area_struct *vma, > > inc_mm_counter_fast(mm, MM_ANONPAGES); > dec_mm_counter_fast(mm, MM_SWAPENTS); > - pte = mk_pte(page, vma->vm_page_prot); > + > + /* > + * Every page swapped-out was pte_dirty so we makes pte dirty again. > + * MADV_FREE relys on it. > + */ > + pte = mk_pte(pte_mkdirty(page), vma->vm_page_prot); pte_mkdirty() usage seems wrong here. > if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { > - pte = maybe_mkwrite(pte_mkdirty(pte), vma); > + pte = maybe_mkwrite(pte, vma); > flags &= ~FAULT_FLAG_WRITE; > ret |= VM_FAULT_WRITE; > exclusive = 1; > diff --git a/mm/rmap.c b/mm/rmap.c > index 47b3ba8..34c1d66 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1268,7 +1268,7 @@ static int try_to_unmap_one(struct page *page, struct > vm_area_struct *vma, > > if (flags & TTU_FREE) { > VM_BUG_ON_PAGE(PageSwapCache(page), page); > - if (!dirty && !PageDirty(page)) { > + if (!dirty) { > /* It's a freeable page by MADV_FREE */ > dec_mm_counter(mm, MM_ANONPAGES); > goto discard; > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 671e47e..7f520c9 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -805,8 +805,7 @@ static enum page_references > page_check_references(struct page *page, > return PAGEREF_KEEP; > } > > - if (PageAnon(page) && !pte_dirty && !PageSwapCache(page) && > - !PageDirty(page)) > + if (PageAnon(page) && !pte_dirty && !PageSwapCache(page)) > *freeable = true; > > /* Reclaim if clean, defer dirty pages to writeback */ > -- > 1.9.3 Could we remove SetPageDirty(page); in try_to_free_swap() function based on this patch? Because your patch will make sure the pte is always dirty, We don't need setpagedirty(), The try_to_unmap() path will re-dirty the page during reclaim path, Isn't it? Thanks