From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 559056B7346 for ; Wed, 5 Dec 2018 03:06:20 -0500 (EST) Received: by mail-pf1-f199.google.com with SMTP id h11so16184616pfj.13 for ; Wed, 05 Dec 2018 00:06:20 -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 z197sor24137758pgz.64.2018.12.05.00.06.19 for (Google Transport Security); Wed, 05 Dec 2018 00:06:19 -0800 (PST) From: Pingfan Liu Subject: [PATCH] mm/pageblock: throw compiling time error if pageblock_bits can not hold MIGRATE_TYPES Date: Wed, 5 Dec 2018 16:05:55 +0800 Message-Id: <1543997155-18344-1-git-send-email-kernelfans@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Pingfan Liu 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. 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 --- include/linux/pageblock-flags.h | 5 +++-- mm/page_alloc.c | 2 +- 2 files changed, 4 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..537020f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -425,7 +425,7 @@ 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); bitmap = get_pageblock_bitmap(page, pfn); bitidx = pfn_to_bitidx(page, pfn); -- 2.7.4