From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 9FB0A6B0389 for ; Thu, 23 Feb 2017 21:12:22 -0500 (EST) Received: by mail-pg0-f70.google.com with SMTP id 1so15871781pgz.5 for ; Thu, 23 Feb 2017 18:12:22 -0800 (PST) Received: from lgeamrelo13.lge.com (LGEAMRELO13.lge.com. [156.147.23.53]) by mx.google.com with ESMTP id m1si5928508plb.1.2017.02.23.18.12.20 for ; Thu, 23 Feb 2017 18:12:21 -0800 (PST) Date: Fri, 24 Feb 2017 11:12:18 +0900 From: Minchan Kim Subject: Re: [PATCH V4 4/6] mm: reclaim MADV_FREE pages Message-ID: <20170224021218.GD9818@bbox> References: <94eccf0fcf927f31377a60d7a9f900b7e743fb06.1487788131.git.shli@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <94eccf0fcf927f31377a60d7a9f900b7e743fb06.1487788131.git.shli@fb.com> Sender: owner-linux-mm@kvack.org List-ID: To: Shaohua Li Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kernel-team@fb.com, mhocko@suse.com, hughd@google.com, hannes@cmpxchg.org, riel@redhat.com, mgorman@techsingularity.net, akpm@linux-foundation.org On Wed, Feb 22, 2017 at 10:50:42AM -0800, Shaohua Li wrote: > 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 > > Cc: Michal Hocko > Cc: Minchan Kim > Cc: Hugh Dickins > Cc: Johannes Weiner > Cc: Rik van Riel > Cc: Mel Gorman > Cc: Andrew Morton > Signed-off-by: Shaohua Li > --- > include/linux/rmap.h | 2 +- > mm/huge_memory.c | 2 ++ > mm/madvise.c | 1 + > mm/rmap.c | 10 ++++++++-- > mm/vmscan.c | 34 ++++++++++++++++++++++------------ > 5 files changed, 34 insertions(+), 15 deletions(-) > > diff --git a/include/linux/rmap.h b/include/linux/rmap.h > index e2cd8f9..2bfd8c6 100644 > --- a/include/linux/rmap.h > +++ b/include/linux/rmap.h > @@ -300,6 +300,6 @@ static inline int page_mkclean(struct page *page) > #define SWAP_AGAIN 1 > #define SWAP_FAIL 2 > #define SWAP_MLOCK 3 > -#define SWAP_LZFREE 4 > +#define SWAP_DIRTY 4 Could you write down about SWAP_DIRTY in try_to_unmap's description? < snip > > diff --git a/mm/rmap.c b/mm/rmap.c > index c621088..083f32e 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1424,6 +1424,12 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, > 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; > } > > if (swap_duplicate(entry) < 0) { > @@ -1525,8 +1531,8 @@ int try_to_unmap(struct page *page, enum ttu_flags flags) > > if (ret != SWAP_MLOCK && !page_mapcount(page)) { > ret = SWAP_SUCCESS; > - if (rp.lazyfreed && !PageDirty(page)) > - ret = SWAP_LZFREE; > + if (rp.lazyfreed && PageDirty(page)) > + ret = SWAP_DIRTY; Hmm, I don't understand why we need to introduce new return value. Can't we set SetPageSwapBacked and return SWAP_FAIL in try_to_unmap_one? > } > return ret; > } > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 68ea50d..830981a 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c < snip > > goto keep_locked; > > /* Double the slab pressure for mapped and swapcache pages */ > - if (page_mapped(page) || PageSwapCache(page)) > + if ((page_mapped(page) || PageSwapCache(page)) && > + !(PageAnon(page) && !PageSwapBacked(page))) > sc->nr_scanned++; > > may_enter_fs = (sc->gfp_mask & __GFP_FS) || > @@ -1118,8 +1120,10 @@ static unsigned long shrink_page_list(struct list_head *page_list, > /* > * Anonymous process memory has backing store? > * Try to allocate it some swap space here. > + * Lazyfree page could be freed directly > */ > - if (PageAnon(page) && !PageSwapCache(page)) { > + if (PageAnon(page) && !PageSwapCache(page) && > + PageSwapBacked(page)) { > if (!(sc->gfp_mask & __GFP_IO)) > goto keep_locked; > if (!add_to_swap(page, page_list)) > @@ -1140,9 +1144,12 @@ static unsigned long shrink_page_list(struct list_head *page_list, > * The page is mapped into the page tables of one or more > * processes. Try to unmap it here. > */ > - if (page_mapped(page) && mapping) { > + if (page_mapped(page)) { > switch (ret = try_to_unmap(page, > ttu_flags | TTU_BATCH_FLUSH)) { > + case SWAP_DIRTY: > + SetPageSwapBacked(page); > + /* fall through */ > case SWAP_FAIL: > nr_unmap_fail++; > goto activate_locked; -- 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