From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D0E60C43613 for ; Thu, 20 Jun 2019 07:04:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 92A50208CB for ; Thu, 20 Jun 2019 07:04:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 92A50208CB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 283956B0003; Thu, 20 Jun 2019 03:04:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2343C8E0002; Thu, 20 Jun 2019 03:04:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0FB9A8E0001; Thu, 20 Jun 2019 03:04:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by kanga.kvack.org (Postfix) with ESMTP id B62306B0003 for ; Thu, 20 Jun 2019 03:04:48 -0400 (EDT) Received: by mail-ed1-f71.google.com with SMTP id l26so2993207eda.2 for ; Thu, 20 Jun 2019 00:04:48 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:references:mime-version:content-disposition :in-reply-to:user-agent; bh=L+/CEm3ZufaqHTmvBpNnmNXe4K9WQ1vzNi1EkiNTph4=; b=gzT0Cd4Yk5Vqy6DROivRIHm1Sr/0ocvDtquuZbCKWCUMuFZJ6mkEHw1dPZZbTUGgIw oSE/LuQktXW5iM8JMSYen4V4KkiJUafNHINzQOYT+2NVzKUWi97dOCXoYqpxpXzPQv5f vxotJyd9k1mcTr6nQ2LewDBBAXbI4h5Qos+vysUlE2aooswfBE+R0eCcSx6/1uNQzS79 5k5S6QbMn9qqlY6W3VaGluJpUwgeoNyaKfpr3LUJP9YYLajj3s9S6ZJEdffNEC0GkEJQ yRaJgfYmZ9K9rwzAq0DCTSEkDL7efHbp1aPvdX3ssBhrWIMWoAYoWxUXoJgMsm0Z3qW9 cd5Q== X-Original-Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Gm-Message-State: APjAAAW+asAEHHtNLrJyvsv5ui3l2nP3YuhuZUXsvuUCrkBYbznPVo2D DHa5AyasC6VvPS/5mIsp4TacgNk3YOFGNmHLvn5EX7AwZ+wy2Dw5kis1zV0OIiUt+WCO3DMTriP vwjFpETzGTJIRCKVO/2x8vGHDM6TLf00GGbjS/BW6H6krX023NX1dsdSKssxDhQI= X-Received: by 2002:a17:906:19d3:: with SMTP id h19mr13552732ejd.300.1561014288289; Thu, 20 Jun 2019 00:04:48 -0700 (PDT) X-Google-Smtp-Source: APXvYqwgMIc0ObpzxURglG57STOjvej0dXSzCCuJ1Q40gXwoZWT4S+VybWxOMQFaRHCfLugRBN/s X-Received: by 2002:a17:906:19d3:: with SMTP id h19mr13552664ejd.300.1561014287327; Thu, 20 Jun 2019 00:04:47 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1561014287; cv=none; d=google.com; s=arc-20160816; b=cwkqfe47r1a+xbKCgz9Et+Bzav+s76FA7mKlcqSa0aXcnALp23KdqSQS+HT6p9O8ok 2oAGIlnH2BjPYAGiFVYfh5SO2/1d3GlrG+s7r2rcFGXhkVnhjN7NYDXBRPWIrrtyI7ze QGnPYQ1ZR6oSHYyMBpVMRRWsajww6+wjFMxtvU5m79hYiclyDhm7dFrJMz8KxmwLmMKs Ok2PBll/0wkqQQOzRmybBEcnAOJgwvA76QJZ9F0Yiy32DbdNlEsGnVrb/i8I3TErlB5K gXKqldC5Ad+zdnLQwNV9aB4hbLWkt4xW1jWLOE+gXdtUOqrKUOAVIWxecMP6DIN3zY0G T6Mw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date; bh=L+/CEm3ZufaqHTmvBpNnmNXe4K9WQ1vzNi1EkiNTph4=; b=xp46Qz+hfaX/3qx6H1DdKxmM6dF5RfKoI/1TLLfOlthT1TFUWuyJOvQrmKP9b1Z7SE SRgUcEgQv3x29eHbRvJOPriE7yNQ4nzAbUBgCJU5s53S+VvajYVTrbmYTcRsyLQxp1Yq k6gTGaOUZLkieH3lst7tS1FIISiyB/79sNUhvHJL20gJxKubRQ6o1aa9oBo2Jc1DELgS jLRimWnegJDf8d8yNjjkFjsWJthbCTgRI0UxO85kaa5ZAMuDD8SG3asGxQUToFPY+Pjw Pml5WH64ZGsZIN2mV1usSiwELoeH0QMhnrngavyXtqeYvBLQLdEIs9EVpAg0fzBC9WZP fVGg== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id z13si4645087ejm.227.2019.06.20.00.04.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 20 Jun 2019 00:04:47 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A60D3AE34; Thu, 20 Jun 2019 07:04:46 +0000 (UTC) Date: Thu, 20 Jun 2019 09:04:44 +0200 From: Michal Hocko To: Minchan Kim Cc: Andrew Morton , linux-mm , LKML , linux-api@vger.kernel.org, Johannes Weiner , Tim Murray , Joel Fernandes , Suren Baghdasaryan , Daniel Colascione , Shakeel Butt , Sonny Rao , Brian Geffon , jannh@google.com, oleg@redhat.com, christian@brauner.io, oleksandr@redhat.com, hdanton@sina.com, lizeb@google.com Subject: Re: [PATCH v2 4/5] mm: introduce MADV_PAGEOUT Message-ID: <20190620070444.GB12083@dhcp22.suse.cz> References: <20190610111252.239156-1-minchan@kernel.org> <20190610111252.239156-5-minchan@kernel.org> <20190619132450.GQ2968@dhcp22.suse.cz> <20190620041620.GB105727@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190620041620.GB105727@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu 20-06-19 13:16:20, Minchan Kim wrote: > On Wed, Jun 19, 2019 at 03:24:50PM +0200, Michal Hocko wrote: > > On Mon 10-06-19 20:12:51, Minchan Kim wrote: > > [...] > > > +static int madvise_pageout_pte_range(pmd_t *pmd, unsigned long addr, > > > + unsigned long end, struct mm_walk *walk) > > > > Again the same question about a potential code reuse... > > [...] > > > +regular_page: > > > + tlb_change_page_size(tlb, PAGE_SIZE); > > > + orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); > > > + flush_tlb_batched_pending(mm); > > > + arch_enter_lazy_mmu_mode(); > > > + for (; addr < end; pte++, addr += PAGE_SIZE) { > > > + ptent = *pte; > > > + if (!pte_present(ptent)) > > > + continue; > > > + > > > + page = vm_normal_page(vma, addr, ptent); > > > + if (!page) > > > + continue; > > > + > > > + if (isolate_lru_page(page)) > > > + continue; > > > + > > > + isolated++; > > > + if (pte_young(ptent)) { > > > + ptent = ptep_get_and_clear_full(mm, addr, pte, > > > + tlb->fullmm); > > > + ptent = pte_mkold(ptent); > > > + set_pte_at(mm, addr, pte, ptent); > > > + tlb_remove_tlb_entry(tlb, pte, addr); > > > + } > > > + ClearPageReferenced(page); > > > + test_and_clear_page_young(page); > > > + list_add(&page->lru, &page_list); > > > + if (isolated >= SWAP_CLUSTER_MAX) { > > > > Why do we need SWAP_CLUSTER_MAX batching? Especially when we need ... > > [...] > > It aims for preventing early OOM kill since we isolate too many LRU > pages concurrently. This is a good point. For some reason I thought that we consider isolated pages in should_reclaim_retry but we do not anymore (since we move from zone to node LRUs I guess). Please stick a comment there. > > > +unsigned long reclaim_pages(struct list_head *page_list) > > > +{ > > > + int nid = -1; > > > + unsigned long nr_reclaimed = 0; > > > + LIST_HEAD(node_page_list); > > > + struct reclaim_stat dummy_stat; > > > + struct scan_control sc = { > > > + .gfp_mask = GFP_KERNEL, > > > + .priority = DEF_PRIORITY, > > > + .may_writepage = 1, > > > + .may_unmap = 1, > > > + .may_swap = 1, > > > + }; > > > + > > > + while (!list_empty(page_list)) { > > > + struct page *page; > > > + > > > + page = lru_to_page(page_list); > > > + if (nid == -1) { > > > + nid = page_to_nid(page); > > > + INIT_LIST_HEAD(&node_page_list); > > > + } > > > + > > > + if (nid == page_to_nid(page)) { > > > + list_move(&page->lru, &node_page_list); > > > + continue; > > > + } > > > + > > > + nr_reclaimed += shrink_page_list(&node_page_list, > > > + NODE_DATA(nid), > > > + &sc, 0, > > > + &dummy_stat, false); > > > > per-node batching in fact. Other than that nothing really jumped at me. > > Except for the shared page cache side channel timing aspect not being > > considered AFAICS. To be more specific. Pushing out a shared page cache > > is possible even now but this interface gives a much easier tool to > > evict shared state and perform all sorts of timing attacks. Unless I am > > missing something we should be doing something similar to mincore and > > ignore shared pages without a writeable access or at least document why > > we do not care. > > I'm not sure IIUC side channel attach. As you mentioned, without this syscall, > 1. they already can do that simply by memory hogging This is way much more harder for practical attacks because the reclaim logic is not fully under the attackers control. Having a direct tool to reclaim memory directly then just opens doors to measure the other consumers of that memory and all sorts of side channel. > 2. If we need fix MADV_PAGEOUT, that means we need to fix MADV_DONTNEED, too? nope because MADV_DONTNEED doesn't unmap from other processes. -- Michal Hocko SUSE Labs