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=-6.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 03C64C3279D for ; Tue, 6 Oct 2020 20:51:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BCFD120897 for ; Tue, 6 Oct 2020 20:51:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727489AbgJFUvo (ORCPT ); Tue, 6 Oct 2020 16:51:44 -0400 Received: from mga09.intel.com ([134.134.136.24]:31014 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727350AbgJFUvZ (ORCPT ); Tue, 6 Oct 2020 16:51:25 -0400 IronPort-SDR: KD1bJXV7CGbGZkEf4tTmhIc1cut2LiTjmXwmsaX1zT+B2PaXvO9M4HZ8Z4eH3sO2bT86B2oG8R q9RnibkRuPow== X-IronPort-AV: E=McAfee;i="6000,8403,9766"; a="164821948" X-IronPort-AV: E=Sophos;i="5.77,343,1596524400"; d="scan'208";a="164821948" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Oct 2020 13:51:23 -0700 IronPort-SDR: SyolvwxwHnqxO3CoFZSegWDDqM/zebfgMb0LsXEyn+M2hKRNkazkvoxIv1WJl7QMg6+3Celuxd LUrhHoukD5ng== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,343,1596524400"; d="scan'208";a="348675670" Received: from viggo.jf.intel.com (HELO localhost.localdomain) ([10.54.77.144]) by fmsmga002.fm.intel.com with ESMTP; 06 Oct 2020 13:51:23 -0700 Subject: [RFC][PATCH 08/12] mm/migrate: demote pages during reclaim To: linux-kernel@vger.kernel.org Cc: Dave Hansen , yang.shi@linux.alibaba.com, rientjes@google.com, ying.huang@intel.com, dan.j.williams@intel.com From: Dave Hansen Date: Tue, 06 Oct 2020 13:51:19 -0700 References: <20201006205103.268F74A9@viggo.jf.intel.com> In-Reply-To: <20201006205103.268F74A9@viggo.jf.intel.com> Message-Id: <20201006205119.FA157F63@viggo.jf.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen This is mostly derived from a patch from Yang Shi: https://lore.kernel.org/linux-mm/1560468577-101178-10-git-send-email-yang.shi@linux.alibaba.com/ Add code to the reclaim path (shrink_page_list()) to "demote" data to another NUMA node instead of discarding the data. This always avoids the cost of I/O needed to read the page back in and sometimes avoids the writeout cost when the pagee is dirty. A second pass through shrink_page_list() will be made if any demotions fail. This essentally falls back to normal reclaim behavior in the case that demotions fail. Previous versions of this patch may have simply failed to reclaim pages which were eligible for demotion but were unable to be demoted in practice. Note: This just adds the start of infratructure for migration. It is actually disabled next to the FIXME in migrate_demote_page_ok(). Signed-off-by: Dave Hansen Cc: Yang Shi Cc: David Rientjes Cc: Huang Ying Cc: Dan Williams -- changes from 20200730: * Add another pass through shrink_page_list() when demotion fails. --- b/include/linux/migrate.h | 2 b/mm/vmscan.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 99 insertions(+) diff -puN include/linux/migrate.h~demote-with-migrate_pages include/linux/migrate.h --- a/include/linux/migrate.h~demote-with-migrate_pages 2020-10-06 13:39:29.059818422 -0700 +++ b/include/linux/migrate.h 2020-10-06 13:39:29.067818422 -0700 @@ -27,6 +27,7 @@ enum migrate_reason { MR_MEMPOLICY_MBIND, MR_NUMA_MISPLACED, MR_CONTIG_RANGE, + MR_DEMOTION, MR_TYPES }; @@ -196,6 +197,7 @@ struct migrate_vma { int migrate_vma_setup(struct migrate_vma *args); void migrate_vma_pages(struct migrate_vma *migrate); void migrate_vma_finalize(struct migrate_vma *migrate); +int next_demotion_node(int node); #endif /* CONFIG_MIGRATION */ diff -puN mm/vmscan.c~demote-with-migrate_pages mm/vmscan.c --- a/mm/vmscan.c~demote-with-migrate_pages 2020-10-06 13:39:29.061818422 -0700 +++ b/mm/vmscan.c 2020-10-06 13:39:29.068818422 -0700 @@ -43,6 +43,7 @@ #include #include #include +#include #include #include #include @@ -1034,6 +1035,24 @@ static enum page_references page_check_r return PAGEREF_RECLAIM; } +bool migrate_demote_page_ok(struct page *page, struct scan_control *sc) +{ + int next_nid = next_demotion_node(page_to_nid(page)); + + VM_BUG_ON_PAGE(!PageLocked(page), page); + VM_BUG_ON_PAGE(PageHuge(page), page); + VM_BUG_ON_PAGE(PageLRU(page), page); + + if (next_nid == NUMA_NO_NODE) + return false; + if (PageTransHuge(page) && !thp_migration_supported()) + return false; + + // FIXME: actually enable this later in the series + return false; +} + + /* Check if a page is dirty or under writeback */ static void page_check_dirty_writeback(struct page *page, bool *dirty, bool *writeback) @@ -1064,6 +1083,60 @@ static void page_check_dirty_writeback(s mapping->a_ops->is_dirty_writeback(page, dirty, writeback); } +static struct page *alloc_demote_page(struct page *page, unsigned long node) +{ + /* + * Try to fail quickly if memory on the target node is not + * available. Leaving out __GFP_IO and __GFP_FS helps with + * this. If the desintation node is full, we want kswapd to + * run there so that its pages will get reclaimed and future + * migration attempts may succeed. + */ + gfp_t flags = (__GFP_HIGHMEM | __GFP_MOVABLE | __GFP_NORETRY | + __GFP_NOMEMALLOC | __GFP_NOWARN | __GFP_THISNODE | + __GFP_KSWAPD_RECLAIM); + /* HugeTLB pages should not be on the LRU */ + WARN_ON_ONCE(PageHuge(page)); + + if (PageTransHuge(page)) { + struct page *thp; + + flags |= __GFP_COMP; + + thp = alloc_pages_node(node, flags, HPAGE_PMD_ORDER); + if (!thp) + return NULL; + prep_transhuge_page(thp); + return thp; + } + + return __alloc_pages_node(node, flags, 0); +} + +/* + * Take pages on @demote_list and attempt to demote them to + * another node. Pages which are not demoted are left on + * @demote_pages. + */ +static unsigned int demote_page_list(struct list_head *demote_pages, + struct pglist_data *pgdat, + struct scan_control *sc) +{ + int target_nid = next_demotion_node(pgdat->node_id); + unsigned int nr_succeeded = 0; + int err; + + if (list_empty(demote_pages)) + return 0; + + /* Demotion ignores all cpuset and mempolicy settings */ + err = migrate_pages(demote_pages, alloc_demote_page, NULL, + target_nid, MIGRATE_ASYNC, MR_DEMOTION, + &nr_succeeded); + + return nr_succeeded; +} + /* * shrink_page_list() returns the number of reclaimed pages */ @@ -1076,12 +1149,15 @@ static unsigned int shrink_page_list(str { LIST_HEAD(ret_pages); LIST_HEAD(free_pages); + LIST_HEAD(demote_pages); unsigned int nr_reclaimed = 0; unsigned int pgactivate = 0; + bool do_demote_pass = true; memset(stat, 0, sizeof(*stat)); cond_resched(); +retry: while (!list_empty(page_list)) { struct address_space *mapping; struct page *page; @@ -1231,6 +1307,16 @@ static unsigned int shrink_page_list(str } /* + * Before reclaiming the page, try to relocate + * its contents to another node. + */ + if (do_demote_pass && migrate_demote_page_ok(page, sc)) { + list_add(&page->lru, &demote_pages); + unlock_page(page); + continue; + } + + /* * Anonymous process memory has backing store? * Try to allocate it some swap space here. * Lazyfree page could be freed directly @@ -1477,6 +1563,17 @@ keep: list_add(&page->lru, &ret_pages); VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page); } + /* 'page_list' is always empty here */ + + /* Migrate pages selected for demotion */ + nr_reclaimed += demote_page_list(&demote_pages, pgdat, sc); + /* Pages that could not be demoted are still in @demote_pages */ + if (!list_empty(&demote_pages)) { + /* Pages which failed to demoted go back on on @page_list for retry: */ + list_splice_init(&demote_pages, page_list); + do_demote_pass = false; + goto retry; + } pgactivate = stat->nr_activate[0] + stat->nr_activate[1]; _