Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752660AbdCFDDt (ORCPT ); Sun, 5 Mar 2017 22:03:49 -0500 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:50488 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752607AbdCFDDr (ORCPT ); Sun, 5 Mar 2017 22:03:47 -0500 X-Original-SENDERIP: 156.147.1.126 X-Original-MAILFROM: minchan@kernel.org X-Original-SENDERIP: 10.177.223.161 X-Original-MAILFROM: minchan@kernel.org Date: Mon, 6 Mar 2017 12:03:44 +0900 From: Minchan Kim To: Johannes Weiner Cc: linux-kernel@vger.kernel.org, shli@fb.com, hillf.zj@alibaba-inc.com, hughd@google.com, mgorman@techsingularity.net, mhocko@suse.com, riel@redhat.com, mm-commits@vger.kernel.org Subject: Re: + mm-reclaim-madv_free-pages.patch added to -mm tree Message-ID: <20170306030344.GG8779@bbox> References: <58b616a6.hCl1D/BVn0fPDi+K%akpm@linux-foundation.org> <20170303025237.GB3503@bbox> <20170303151851.GA16835@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170303151851.GA16835@cmpxchg.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7196 Lines: 199 On Fri, Mar 03, 2017 at 10:18:51AM -0500, Johannes Weiner wrote: > On Fri, Mar 03, 2017 at 11:52:37AM +0900, Minchan Kim wrote: > > On Tue, Feb 28, 2017 at 04:32:38PM -0800, akpm@linux-foundation.org wrote: > > > > > > The patch titled > > > Subject: mm: reclaim MADV_FREE pages > > > has been added to the -mm tree. Its filename is > > > mm-reclaim-madv_free-pages.patch > > > > > > This patch should soon appear at > > > http://ozlabs.org/~akpm/mmots/broken-out/mm-reclaim-madv_free-pages.patch > > > and later at > > > http://ozlabs.org/~akpm/mmotm/broken-out/mm-reclaim-madv_free-pages.patch > > > > > > Before you just go and hit "reply", please: > > > a) Consider who else should be cc'ed > > > b) Prefer to cc a suitable mailing list as well > > > c) Ideally: find the original patch on the mailing list and do a > > > reply-to-all to that, adding suitable additional cc's > > > > > > *** Remember to use Documentation/SubmitChecklist when testing your code *** > > > > > > The -mm tree is included into linux-next and is updated > > > there every 3-4 working days > > > > > > ------------------------------------------------------ > > > From: Shaohua Li > > > Subject: mm: reclaim MADV_FREE pages > > > > > > When memory pressure is high, we free MADV_FREE pages. If the pages are > > > not dirty in pte, the pages could be freed immediately. Otherwise we > > > can't reclaim them. We put the pages back to anonumous LRU list (by > > > setting SwapBacked flag) and the pages will be reclaimed in normal swapout > > > way. > > > > > > We use normal page reclaim policy. Since MADV_FREE pages are put into > > > inactive file list, such pages and inactive file pages are reclaimed > > > according to their age. This is expected, because we don't want to > > > reclaim too many MADV_FREE pages before used once pages. > > > > > > Based on Minchan's original patch > > > > > > Link: http://lkml.kernel.org/r/14b8eb1d3f6bf6cc492833f183ac8c304e560484.1487965799.git.shli@fb.com > > > Signed-off-by: Shaohua Li > > > Acked-by: Minchan Kim > > > Acked-by: Michal Hocko > > > Acked-by: Johannes Weiner > > > Acked-by: Hillf Danton > > > Cc: Hugh Dickins > > > Cc: Rik van Riel > > > Cc: Mel Gorman > > > Signed-off-by: Andrew Morton > > > --- > > > > < snip > > > > > > @@ -1419,11 +1413,21 @@ static int try_to_unmap_one(struct page > > > VM_BUG_ON_PAGE(!PageSwapCache(page) && PageSwapBacked(page), > > > page); > > > > > > - if (!PageDirty(page)) { > > > + /* > > > + * swapin page could be clean, it has data stored in > > > + * swap. We can't silently discard it without setting > > > + * swap entry in the page table. > > > + */ > > > + if (!PageDirty(page) && !PageSwapCache(page)) { > > > /* It's a freeable page by MADV_FREE */ > > > dec_mm_counter(mm, MM_ANONPAGES); > > > - rp->lazyfreed++; > > > goto discard; > > > + } else if (!PageSwapBacked(page)) { > > > + /* dirty MADV_FREE page */ > > > + set_pte_at(mm, address, pvmw.pte, pteval); > > > + ret = SWAP_DIRTY; > > > + page_vma_mapped_walk_done(&pvmw); > > > + break; > > > } > > > > There is no point to make this logic complicated with clean swapin-page. > > > > Andrew, > > Could you fold below patch into the mm-reclaim-madv_free-pages.patch > > if others are not against? > > > > Thanks. > > > > From 0c28f6560fbc4e65da4f4a8cc4664ab9f7b11cf3 Mon Sep 17 00:00:00 2001 > > From: Minchan Kim > > Date: Fri, 3 Mar 2017 11:42:52 +0900 > > Subject: [PATCH] mm: clean up lazyfree page handling > > > > We can make it simple to understand without need to be aware of > > clean-swapin page. > > This patch just clean up lazyfree page handling in try_to_unmap_one. > > > > Signed-off-by: Minchan Kim > > Agreed, this is a litle easier to follow. > > Acked-by: Johannes Weiner Thanks, Johannes. > > > --- > > mm/rmap.c | 22 +++++++++++----------- > > 1 file changed, 11 insertions(+), 11 deletions(-) > > > > diff --git a/mm/rmap.c b/mm/rmap.c > > index bb45712..f7eab40 100644 > > --- a/mm/rmap.c > > +++ b/mm/rmap.c > > @@ -1413,17 +1413,17 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, > > VM_BUG_ON_PAGE(!PageSwapCache(page) && PageSwapBacked(page), > > page); > > Since you're removing the PageSwapCache() check and we're now assuming > that !swapbacked is not in the swapcache, can you modify this to check > PageSwapBacked(page) != PageSwapCache(page)? > > Better yet, change it into a warning and SWAP_FAIL. Maybe, what you wanted is !!PageSwapBacked(page) != !!PageSwapCache(page) Personally, I prefer && style rather than equation expression in this case. How about this? If others are not against, I will resend it to Andrew with Acked|Reviewed-by all I got until now. Thanks. commit 118cfee42600 Author: Minchan Kim Date: Sat Mar 4 01:01:38 2017 +0000 mm: clean up lazyfree page handling We can make it simple to understand without need to be aware of clean-swapin page. This patch just clean up lazyfree page handling in try_to_unmap_one. Link: http://lkml.kernel.org/r/20170303025237.GB3503@bbox Signed-off-by: Minchan Kim Cc: Shaohua Li Cc: Michal Hocko Cc: Johannes Weiner Cc: Hillf Danton Cc: Hugh Dickins Cc: Rik van Riel Cc: Mel Gorman Signed-off-by: Andrew Morton diff --git a/mm/rmap.c b/mm/rmap.c index 3d86036d96ec..1377f7b0361e 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1413,20 +1413,24 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, * Store the swap location in the pte. * See handle_pte_fault() ... */ - VM_BUG_ON_PAGE(!PageSwapCache(page) && PageSwapBacked(page), - page); + if (VM_WARN_ON_ONCE(PageSwapBacked(page) && + !PageSwapCache(page))) { + ret = SWAP_FAIL; + page_vma_mapped_walk_done(&pvmw); + break; + } - /* - * swapin page could be clean, it has data stored in - * swap. We can't silently discard it without setting - * swap entry in the page table. - */ - if (!PageDirty(page) && !PageSwapCache(page)) { - /* It's a freeable page by MADV_FREE */ - dec_mm_counter(mm, MM_ANONPAGES); - goto discard; - } else if (!PageSwapBacked(page)) { - /* dirty MADV_FREE page */ + /* MADV_FREE page check */ + if (!PageSwapBacked(page)) { + if (!PageDirty(page)) { + dec_mm_counter(mm, MM_ANONPAGES); + goto discard; + } + + /* + * If the page was redirtied, it cannot be + * discarded. Remap the page to page table. + */ set_pte_at(mm, address, pvmw.pte, pteval); ret = SWAP_DIRTY; page_vma_mapped_walk_done(&pvmw);