diff mbox series

[v18,05/32] mm/thp: remove code path which never got into

Message ID	1598273705-69124-6-git-send-email-alex.shi@linux.alibaba.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=JPLW=CC=kvack.org=owner-linux-mm@kernel.org> DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E4BF120706 From: Alex Shi <alex.shi@linux.alibaba.com> To: akpm@linux-foundation.org, mgorman@techsingularity.net, tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.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, kirill@shutemov.name, alexander.duyck@gmail.com, rong.a.chen@intel.com, mhocko@suse.com, vdavydov.dev@gmail.com, shy828301@gmail.com Subject: [PATCH v18 05/32] mm/thp: remove code path which never got into Date: Mon, 24 Aug 2020 20:54:38 +0800 Message-Id: <1598273705-69124-6-git-send-email-alex.shi@linux.alibaba.com> In-Reply-To: <1598273705-69124-1-git-send-email-alex.shi@linux.alibaba.com> References: <1598273705-69124-1-git-send-email-alex.shi@linux.alibaba.com> Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	per memcg lru_lock \| expand [v18,00/32] per memcg lru_lock [v18,01/32] mm/memcg: warning on !memcg after readahead page charged [v18,02/32] mm/memcg: bail out early from swap accounting when memcg is disabled [v18,03/32] mm/thp: move lru_add_page_tail func to huge_memory.c [v18,04/32] mm/thp: clean up lru_add_page_tail [v18,05/32] mm/thp: remove code path which never got into [v18,06/32] mm/thp: narrow lru locking [v18,07/32] mm/swap.c: stop deactivate_file_page if page not on lru [v18,08/32] mm/vmscan: remove unnecessary lruvec adding [v18,09/32] mm/page_idle: no unlikely double check for idle page counting [v18,10/32] mm/compaction: rename compact_deferred as compact_should_defer [v18,11/32] mm/memcg: add debug checking in lock_page_memcg [v18,12/32] mm/memcg: optimize mem_cgroup_page_lruvec [v18,13/32] mm/swap.c: fold vm event PGROTATED into pagevec_move_tail_fn [v18,14/32] mm/lru: move lru_lock holding in func lru_note_cost_page [v18,15/32] mm/lru: move lock into lru_note_cost [v18,16/32] mm/lru: introduce TestClearPageLRU [v18,17/32] mm/compaction: do page isolation first in compaction [v18,18/32] mm/thp: add tail pages into lru anyway in split_huge_page() [v18,19/32] mm/swap.c: serialize memcg changes in pagevec_lru_move_fn [v18,20/32] mm/lru: replace pgdat lru_lock with lruvec lock [v18,21/32] mm/lru: introduce the relock_page_lruvec function [v18,22/32] mm/vmscan: use relock for move_pages_to_lru [v18,23/32] mm/lru: revise the comments of lru_lock [v18,24/32] mm/pgdat: remove pgdat lru_lock [v18,25/32] mm/mlock: remove lru_lock on TestClearPageMlocked in munlock_vma_page [v18,26/32] mm/mlock: remove __munlock_isolate_lru_page [v18,27/32] mm/swap.c: optimizing __pagevec_lru_add lru_lock [v18,28/32] mm/compaction: Drop locked from isolate_migratepages_block [v18,29/32] mm: Identify compound pages sooner in isolate_migratepages_block [v18,30/32] mm: Drop use of test_and_set_skip in favor of just setting skip [v18,31/32] mm: Add explicit page decrement in exception path for isolate_lru_pages [v18,32/32] mm: Split release_pages work into 3 passes

Commit Message

Alex Shi Aug. 24, 2020, 12:54 p.m. UTC

split_huge_page() will never call on a page which isn't on lru list, so
this code never got a chance to run, and should not be run, to add tail
pages on a lru list which head page isn't there.

Although the bug was never triggered, it'better be removed for code
correctness, and add a warn for unexpected calling.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 mm/huge_memory.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff mbox series

Patch

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 739497770a3d..247f53def87b 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2330,17 +2330,8 @@  static void lru_add_page_tail(struct page *head, struct page *page_tail,
 		/* page reclaim is reclaiming a huge page */
 		get_page(page_tail);
 		list_add_tail(&page_tail->lru, list);
-	} else {
-		/*
-		 * Head page has not yet been counted, as an hpage,
-		 * so we must account for each subpage individually.
-		 *
-		 * Put page_tail on the list at the correct position
-		 * so they all end up in order.
-		 */
-		add_page_to_lru_list_tail(page_tail, lruvec,
-					  page_lru(page_tail));
-	}
+	} else
+		VM_WARN_ON(!PageLRU(head));
 }
 
 static void __split_huge_page_tail(struct page *head, int tail,