From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757976AbdJMMAZ (ORCPT ); Fri, 13 Oct 2017 08:00:25 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:37386 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753406AbdJMMAX (ORCPT ); Fri, 13 Oct 2017 08:00:23 -0400 X-Google-Smtp-Source: AOwi7QAfuMHmqY23cXqmASPbsr6hdCGxvSwWsFeZlu7WLd1etoEDBOrJ5BUuPloABppcyE+RyqG/OQ== From: Michal Hocko To: Cc: Michael Ellerman , Vlastimil Babka , Andrew Morton , KAMEZAWA Hiroyuki , Reza Arbab , Yasuaki Ishimatsu , qiuxishi@huawei.com, Igor Mammedov , Vitaly Kuznetsov , LKML , Michal Hocko Subject: [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages Date: Fri, 13 Oct 2017 14:00:12 +0200 Message-Id: <20171013120013.698-1-mhocko@kernel.org> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20171013115835.zaehapuucuzl2vlv@dhcp22.suse.cz> References: <20171013115835.zaehapuucuzl2vlv@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michal Hocko Michael has noticed that the memory offline tries to migrate kernel code pages when doing echo 0 > /sys/devices/system/memory/memory0/online The current implementation will fail the operation after several failed page migration attempts but we shouldn't even attempt to migrate that memory and fail right away because this memory is clearly not migrateable. This will become a real problem when we drop the retry loop counter resp. timeout. The real problem is in has_unmovable_pages in fact. We should fail if there are any non migrateable pages in the area. In orther to guarantee that remove the migrate type checks because MIGRATE_MOVABLE is not guaranteed to contain only migrateable pages. It is merely a heuristic. Similarly MIGRATE_CMA does guarantee that the page allocator doesn't allocate any non-migrateable pages from the block but CMA allocations themselves are unlikely to migrateable. Therefore remove both checks. Reported-by: Michael Ellerman Signed-off-by: Michal Hocko --- mm/page_alloc.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3badcedf96a7..ad0294ab3e4f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7355,9 +7355,6 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, */ if (zone_idx(zone) == ZONE_MOVABLE) return false; - mt = get_pageblock_migratetype(page); - if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt)) - return false; pfn = page_to_pfn(page); for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) { -- 2.14.2