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=-10.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 DE906C433E0 for ; Fri, 3 Jul 2020 05:09:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C159620723 for ; Fri, 3 Jul 2020 05:09:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726715AbgGCFJG (ORCPT ); Fri, 3 Jul 2020 01:09:06 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:49345 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726300AbgGCFIq (ORCPT ); Fri, 3 Jul 2020 01:08:46 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07484;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=16;SR=0;TI=SMTPD_---0U1Y4LGX_1593752912; Received: from alexshi-test.localdomain(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0U1Y4LGX_1593752912) by smtp.aliyun-inc.com(127.0.0.1); Fri, 03 Jul 2020 13:08:39 +0800 From: Alex Shi To: akpm@linux-foundation.org, mgorman@techsingularity.net, tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com, willy@infradead.org, hannes@cmpxchg.org, lkp@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, shakeelb@google.com, iamjoonsoo.kim@lge.com, richard.weiyang@gmail.com Subject: [PATCH v14 13/20] mm/compaction: do page isolation first in compaction Date: Fri, 3 Jul 2020 13:07:46 +0800 Message-Id: <1593752873-4493-14-git-send-email-alex.shi@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1593752873-4493-1-git-send-email-alex.shi@linux.alibaba.com> References: <1593752873-4493-1-git-send-email-alex.shi@linux.alibaba.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Johannes Weiner has suggested: "So here is a crazy idea that may be worth exploring: Right now, pgdat->lru_lock protects both PageLRU *and* the lruvec's linked list. Can we make PageLRU atomic and use it to stabilize the lru_lock instead, and then use the lru_lock only serialize list operations? ..." Yes, this patch is doing so on __isolate_lru_page which is the core page isolation func in compaction and shrinking path. With this patch, the compaction will only deal the PageLRU set and now isolated pages to skip the just alloced page which no LRU bit. And the isolation could exclusive the other isolations in memcg move_account, page migrations and thp split_huge_page. As a side effect, PageLRU may be cleared during shrink_inactive_list path for isolation reason. If so, we can skip that page. Hugh Dickins fixed following bugs in this patch's early version: Fix lots of crashes under compaction load: isolate_migratepages_block() must clean up appropriately when rejecting a page, setting PageLRU again if it had been cleared; and a put_page() after get_page_unless_zero() cannot safely be done while holding locked_lruvec - it may turn out to be the final put_page(), which will take an lruvec lock when PageLRU. And move __isolate_lru_page_prepare back after get_page_unless_zero to make trylock_page() safe: trylock_page() is not safe to use at this time: its setting PG_locked can race with the page being freed or allocated ("Bad page"), and can also erase flags being set by one of those "sole owners" of a freshly allocated page who use non-atomic __SetPageFlag(). Suggested-by: Johannes Weiner Signed-off-by: Alex Shi Cc: Hugh Dickins Cc: Andrew Morton Cc: Matthew Wilcox Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org --- include/linux/swap.h | 2 +- mm/compaction.c | 42 +++++++++++++++++++++++++++++++++--------- mm/vmscan.c | 38 ++++++++++++++++++++++---------------- 3 files changed, 56 insertions(+), 26 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 2c29399b29a0..6d23d3beeff7 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -358,7 +358,7 @@ extern void lru_cache_add_active_or_unevictable(struct page *page, extern unsigned long zone_reclaimable_pages(struct zone *zone); extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order, gfp_t gfp_mask, nodemask_t *mask); -extern int __isolate_lru_page(struct page *page, isolate_mode_t mode); +extern int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode); extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, unsigned long nr_pages, gfp_t gfp_mask, diff --git a/mm/compaction.c b/mm/compaction.c index f14780fc296a..2da2933fe56b 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -869,6 +869,7 @@ static bool too_many_isolated(pg_data_t *pgdat) if (!valid_page && IS_ALIGNED(low_pfn, pageblock_nr_pages)) { if (!cc->ignore_skip_hint && get_pageblock_skip(page)) { low_pfn = end_pfn; + page = NULL; goto isolate_abort; } valid_page = page; @@ -950,6 +951,21 @@ static bool too_many_isolated(pg_data_t *pgdat) if (!(cc->gfp_mask & __GFP_FS) && page_mapping(page)) goto isolate_fail; + /* + * Be careful not to clear PageLRU until after we're + * sure the page is not being freed elsewhere -- the + * page release code relies on it. + */ + if (unlikely(!get_page_unless_zero(page))) + goto isolate_fail; + + if (__isolate_lru_page_prepare(page, isolate_mode) != 0) + goto isolate_fail_put; + + /* Try isolate the page */ + if (!TestClearPageLRU(page)) + goto isolate_fail_put; + /* If we already hold the lock, we can skip some rechecking */ if (!locked) { locked = compact_lock_irqsave(&pgdat->lru_lock, @@ -962,10 +978,6 @@ static bool too_many_isolated(pg_data_t *pgdat) goto isolate_abort; } - /* Recheck PageLRU and PageCompound under lock */ - if (!PageLRU(page)) - goto isolate_fail; - /* * Page become compound since the non-locked check, * and it's on LRU. It can only be a THP so the order @@ -973,16 +985,13 @@ static bool too_many_isolated(pg_data_t *pgdat) */ if (unlikely(PageCompound(page) && !cc->alloc_contig)) { low_pfn += compound_nr(page) - 1; - goto isolate_fail; + SetPageLRU(page); + goto isolate_fail_put; } } lruvec = mem_cgroup_page_lruvec(page, pgdat); - /* Try isolate the page */ - if (__isolate_lru_page(page, isolate_mode) != 0) - goto isolate_fail; - /* The whole page is taken off the LRU; skip the tail pages. */ if (PageCompound(page)) low_pfn += compound_nr(page) - 1; @@ -1011,6 +1020,15 @@ static bool too_many_isolated(pg_data_t *pgdat) } continue; + +isolate_fail_put: + /* Avoid potential deadlock in freeing page under lru_lock */ + if (locked) { + spin_unlock_irqrestore(&pgdat->lru_lock, flags); + locked = false; + } + put_page(page); + isolate_fail: if (!skip_on_failure) continue; @@ -1047,9 +1065,15 @@ static bool too_many_isolated(pg_data_t *pgdat) if (unlikely(low_pfn > end_pfn)) low_pfn = end_pfn; + page = NULL; + isolate_abort: if (locked) spin_unlock_irqrestore(&pgdat->lru_lock, flags); + if (page) { + SetPageLRU(page); + put_page(page); + } /* * Updated the cached scanner pfn once the pageblock has been scanned diff --git a/mm/vmscan.c b/mm/vmscan.c index 18986fefd49b..f77748adc340 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1544,7 +1544,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, * * returns 0 on success, -ve errno on failure. */ -int __isolate_lru_page(struct page *page, isolate_mode_t mode) +int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode) { int ret = -EINVAL; @@ -1598,20 +1598,9 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode) if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) return ret; - if (likely(get_page_unless_zero(page))) { - /* - * Be careful not to clear PageLRU until after we're - * sure the page is not being freed elsewhere -- the - * page release code relies on it. - */ - ClearPageLRU(page); - ret = 0; - } - - return ret; + return 0; } - /* * Update LRU sizes after isolating pages. The LRU size updates must * be complete before mem_cgroup_update_lru_size due to a sanity check. @@ -1691,17 +1680,34 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, * only when the page is being freed somewhere else. */ scan += nr_pages; - switch (__isolate_lru_page(page, mode)) { + switch (__isolate_lru_page_prepare(page, mode)) { case 0: + /* + * Be careful not to clear PageLRU until after we're + * sure the page is not being freed elsewhere -- the + * page release code relies on it. + */ + if (unlikely(!get_page_unless_zero(page))) + goto busy; + + if (!TestClearPageLRU(page)) { + /* + * This page may in other isolation path, + * but we still hold lru_lock. + */ + put_page(page); + goto busy; + } + nr_taken += nr_pages; nr_zone_taken[page_zonenum(page)] += nr_pages; list_move(&page->lru, dst); break; - +busy: case -EBUSY: /* else it is being freed elsewhere */ list_move(&page->lru, src); - continue; + break; default: BUG(); -- 1.8.3.1