From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id C30706B0038 for ; Fri, 13 Oct 2017 08:00:24 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id k4so5874941wmc.20 for ; Fri, 13 Oct 2017 05:00:24 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id 38sor391509wrw.67.2017.10.13.05.00.23 for (Google Transport Security); Fri, 13 Oct 2017 05:00:23 -0700 (PDT) From: 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> In-Reply-To: <20171013115835.zaehapuucuzl2vlv@dhcp22.suse.cz> References: <20171013115835.zaehapuucuzl2vlv@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Michael Ellerman , Vlastimil Babka , Andrew Morton , KAMEZAWA Hiroyuki , Reza Arbab , Yasuaki Ishimatsu , qiuxishi@huawei.com, Igor Mammedov , Vitaly Kuznetsov , LKML , Michal Hocko 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 -- 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