From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f178.google.com (mail-pd0-f178.google.com [209.85.192.178]) by kanga.kvack.org (Postfix) with ESMTP id 187A96B0032 for ; Wed, 11 Feb 2015 02:06:19 -0500 (EST) Received: by pdbft15 with SMTP id ft15so2522496pdb.11 for ; Tue, 10 Feb 2015 23:06:18 -0800 (PST) Received: from mail-pd0-f178.google.com (mail-pd0-f178.google.com. [209.85.192.178]) by mx.google.com with ESMTPS id gp7si29728994pac.26.2015.02.10.23.06.17 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 10 Feb 2015 23:06:18 -0800 (PST) Received: by pdev10 with SMTP id v10so2519594pde.10 for ; Tue, 10 Feb 2015 23:06:17 -0800 (PST) Date: Tue, 10 Feb 2015 23:06:09 -0800 (PST) From: Hugh Dickins Subject: [PATCH] mm: fix negative nr_isolated counts Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Vlastimil Babka , linux-mm@kvack.org The vmstat interfaces are good at hiding negative counts (at least when CONFIG_SMP); but if you peer behind the curtain, you find that nr_isolated_anon and nr_isolated_file soon go negative, and grow ever more negative: so they can absorb larger and larger numbers of isolated pages, yet still appear to be zero. I'm happy to avoid a congestion_wait() when too_many_isolated() myself; but I guess it's there for a good reason, in which case we ought to get too_many_isolated() working again. The imbalance comes from isolate_migratepages()'s ISOLATE_ABORT case: putback_movable_pages() decrements the NR_ISOLATED counts, but we forgot to call acct_isolated() to increment them. Fixes: edc2ca612496 ("mm, compaction: move pageblock checks up from isolate_migratepages_range()") Signed-off-by: Hugh Dickins Cc: stable@vger.kernel.org # v3.18+ --- mm/compaction.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- v3.19/mm/compaction.c 2015-02-08 18:54:22.000000000 -0800 +++ linux/mm/compaction.c 2015-02-10 22:25:04.613907871 -0800 @@ -1015,8 +1015,10 @@ static isolate_migrate_t isolate_migrate low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn, isolate_mode); - if (!low_pfn || cc->contended) + if (!low_pfn || cc->contended) { + acct_isolated(zone, cc); return ISOLATE_ABORT; + } /* * Either we isolated something and proceed with migration. Or -- 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