From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f70.google.com (mail-lf0-f70.google.com [209.85.215.70]) by kanga.kvack.org (Postfix) with ESMTP id 6DE266B025E for ; Fri, 20 May 2016 09:06:52 -0400 (EDT) Received: by mail-lf0-f70.google.com with SMTP id k186so1399292lfe.3 for ; Fri, 20 May 2016 06:06:52 -0700 (PDT) Received: from mail-wm0-f65.google.com (mail-wm0-f65.google.com. [74.125.82.65]) by mx.google.com with ESMTPS id at8si25601035wjc.92.2016.05.20.06.06.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 20 May 2016 06:06:50 -0700 (PDT) Received: by mail-wm0-f65.google.com with SMTP id s63so14518330wme.2 for ; Fri, 20 May 2016 06:06:50 -0700 (PDT) Date: Fri, 20 May 2016 15:06:49 +0200 From: Michal Hocko Subject: Re: [patch] mm, migrate: increment fail count on ENOMEM Message-ID: <20160520130649.GB5197@dhcp22.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Andrew Morton , Vlastimil Babka , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu 19-05-16 15:11:23, David Rientjes wrote: > If page migration fails due to -ENOMEM, nr_failed should still be > incremented for proper statistics. > > This was encountered recently when all page migration vmstats showed 0, > and inferred that migrate_pages() was never called, although in reality > the first page migration failed because compaction_alloc() failed to find > a migration target. > > This patch increments nr_failed so the vmstat is properly accounted on > ENOMEM. > > Signed-off-by: David Rientjes Acked-by: Michal Hocko One question though > --- > mm/migrate.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/migrate.c b/mm/migrate.c > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1171,6 +1171,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, > > switch(rc) { > case -ENOMEM: > + nr_failed++; > goto out; > case -EAGAIN: > retry++; Why don't we need also to count also retries? --- diff --git a/mm/migrate.c b/mm/migrate.c index 53ab6398e7a2..ef9c5211ae3c 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1190,9 +1190,9 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, } } } +out: nr_failed += retry; rc = nr_failed; -out: if (nr_succeeded) count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); if (nr_failed) -- Michal Hocko SUSE Labs -- 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