From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f197.google.com (mail-pg1-f197.google.com [209.85.215.197]) by kanga.kvack.org (Postfix) with ESMTP id 79D6D6B7C6C for ; Thu, 6 Dec 2018 23:53:31 -0500 (EST) Received: by mail-pg1-f197.google.com with SMTP id k125so1771128pga.5 for ; Thu, 06 Dec 2018 20:53:31 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id 73sor3536961plf.73.2018.12.06.20.53.29 for (Google Transport Security); Thu, 06 Dec 2018 20:53:30 -0800 (PST) From: Pingfan Liu Subject: [PATCHv2] mm/pageblock: throw compiling time error if pageblock_bits can not hold MIGRATE_TYPES Date: Fri, 7 Dec 2018 12:53:08 +0800 Message-Id: <1544158388-20832-1-git-send-email-kernelfans@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Pingfan Liu , Andrew Morton , Michal Hocko , Pavel Tatashin , Vlastimil Babka , Oscar Salvador , Mike Rapoport , Joonsoo Kim , Alexander Duyck Currently, NR_PAGEBLOCK_BITS and MIGRATE_TYPES are not associated by code. If someone adds extra migrate type, then he may forget to enlarge the NR_PAGEBLOCK_BITS. Hence it requires some way to fix. NR_PAGEBLOCK_BITS depends on MIGRATE_TYPES, while these macro spread on two different .h file with reverse dependency, it is a little hard to refer to MIGRATE_TYPES in pageblock-flag.h. This patch tries to remind such relation in compiling-time. Signed-off-by: Pingfan Liu Cc: Andrew Morton Cc: Michal Hocko Cc: Pavel Tatashin Cc: Vlastimil Babka Cc: Oscar Salvador Cc: Mike Rapoport Cc: Joonsoo Kim Cc: Alexander Duyck --- include/linux/pageblock-flags.h | 5 +++-- mm/page_alloc.c | 3 ++- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h index 9132c5c..fe0aec4 100644 --- a/include/linux/pageblock-flags.h +++ b/include/linux/pageblock-flags.h @@ -25,11 +25,12 @@ #include +#define PB_migratetype_bits 3 /* Bit indices that affect a whole block of pages */ enum pageblock_bits { PB_migrate, - PB_migrate_end = PB_migrate + 3 - 1, - /* 3 bits required for migrate types */ + PB_migrate_end = PB_migrate + PB_migratetype_bits - 1, + /* n bits required for migrate types */ PB_migrate_skip,/* If set the block is skipped by compaction */ /* diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2ec9cc4..1a22d8d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -425,7 +425,8 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, unsigned long bitidx, word_bitidx; unsigned long old_word, word; - BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); + BUILD_BUG_ON(order_base_2(MIGRATE_TYPES) + != (PB_migratetype_bits - 1)); bitmap = get_pageblock_bitmap(page, pfn); bitidx = pfn_to_bitidx(page, pfn); -- 2.7.4