From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ua0-f199.google.com (mail-ua0-f199.google.com [209.85.217.199]) by kanga.kvack.org (Postfix) with ESMTP id 3802A6B0038 for ; Thu, 23 Feb 2017 12:19:37 -0500 (EST) Received: by mail-ua0-f199.google.com with SMTP id e4so31080783uae.4 for ; Thu, 23 Feb 2017 09:19:37 -0800 (PST) Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com. [67.231.145.42]) by mx.google.com with ESMTPS id o4si5310887iti.126.2017.02.23.09.19.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 23 Feb 2017 09:19:36 -0800 (PST) Date: Thu, 23 Feb 2017 09:19:01 -0800 From: Shaohua Li Subject: Re: [PATCH V4 4/6] mm: reclaim MADV_FREE pages Message-ID: <20170223171901.GA20444@shli-mbp.local> References: <94eccf0fcf927f31377a60d7a9f900b7e743fb06.1487788131.git.shli@fb.com> <20170223161342.GC4031@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20170223161342.GC4031@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kernel-team@fb.com, mhocko@suse.com, minchan@kernel.org, hughd@google.com, riel@redhat.com, mgorman@techsingularity.net, akpm@linux-foundation.org On Thu, Feb 23, 2017 at 11:13:42AM -0500, Johannes Weiner wrote: > On Wed, Feb 22, 2017 at 10:50:42AM -0800, Shaohua Li wrote: > > @@ -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; > > Can this actually happen? If the page is dirty, ret should already be > SWAP_DIRTY, right? How would a dirty page get fully unmapped? > > It seems to me rp.lazyfreed can be removed entirely now that we don't > have to identify the lazyfree case anymore. The failure case is much > easier to identify - all it takes is a single pte to be dirty. ok, I get mixed up. Yes, this couldn't happen any more since we changed the behavior of try_to_unmap_one. Will delete this in next post. Thanks, Shaohua -- 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