From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by kanga.kvack.org (Postfix) with ESMTP id 8E1AB8E004D for ; Tue, 11 Dec 2018 01:12:13 -0500 (EST) Received: by mail-pl1-f200.google.com with SMTP id v11so9934618ply.4 for ; Mon, 10 Dec 2018 22:12:13 -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 d4sor19296713pls.69.2018.12.10.22.12.11 for (Google Transport Security); Mon, 10 Dec 2018 22:12:11 -0800 (PST) From: Pingfan Liu Subject: [PATCHv3] mm/pageblock: throw compiling time error if pageblock_bits can not hold MIGRATE_TYPES Date: Tue, 11 Dec 2018 14:11:49 +0800 Message-Id: <1544508709-11358-1-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 --- v2->v3: using '>' instead of "==" option since NR_PAGEBLOCK_BITS allows wasted bits include/linux/pageblock-flags.h | 3 ++- mm/page_alloc.c | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h index 9132c5c..06a6632 100644 --- a/include/linux/pageblock-flags.h +++ b/include/linux/pageblock-flags.h @@ -25,10 +25,11 @@ #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, + PB_migrate_end = PB_migrate + PB_migratetype_bits - 1, /* 3 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..29ee87e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -426,6 +426,7 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, unsigned long old_word, word; BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); + BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits)); bitmap = get_pageblock_bitmap(page, pfn); bitidx = pfn_to_bitidx(page, pfn); -- 2.7.4