Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754645AbbHDXaz (ORCPT ); Tue, 4 Aug 2015 19:30:55 -0400 Received: from mail-pd0-f175.google.com ([209.85.192.175]:33944 "EHLO mail-pd0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754567AbbHDXay (ORCPT ); Tue, 4 Aug 2015 19:30:54 -0400 Date: Wed, 5 Aug 2015 08:31:08 +0900 From: Minchan Kim To: Andrew Morton Cc: Jaewon Kim , mgorman@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jaewon31.kim@gmail.com Subject: Re: [PATCH v2] vmscan: fix increasing nr_isolated incurred by putback unevictable pages Message-ID: <20150804233108.GA662@bgram> References: <1438684808-12707-1-git-send-email-jaewon31.kim@samsung.com> <20150804150937.ee3b62257e77911a2f41a48e@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150804150937.ee3b62257e77911a2f41a48e@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1652 Lines: 51 Hello, On Tue, Aug 04, 2015 at 03:09:37PM -0700, Andrew Morton wrote: > On Tue, 04 Aug 2015 19:40:08 +0900 Jaewon Kim wrote: > > > reclaim_clean_pages_from_list() assumes that shrink_page_list() returns > > number of pages removed from the candidate list. But shrink_page_list() > > puts back mlocked pages without passing it to caller and without > > counting as nr_reclaimed. This incurrs increasing nr_isolated. > > To fix this, this patch changes shrink_page_list() to pass unevictable > > pages back to caller. Caller will take care those pages. > > > > .. > > > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1157,7 +1157,7 @@ cull_mlocked: > > if (PageSwapCache(page)) > > try_to_free_swap(page); > > unlock_page(page); > > - putback_lru_page(page); > > + list_add(&page->lru, &ret_pages); > > continue; > > > > activate_locked: > > Is this going to cause a whole bunch of mlocked pages to be migrated > whereas in current kernels they stay where they are? > It fixes two issues. 1. With unevictable page, cma_alloc will be successful. Exactly speaking, cma_alloc of current kernel will fail due to unevictable pages. 2. fix leaking of NR_ISOLATED counter of vmstat With it, too_many_isolated works. Otherwise, it could make hang until the process get SIGKILL. So, I think it's stable material. Acked-by: Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/