From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f69.google.com (mail-pl0-f69.google.com [209.85.160.69]) by kanga.kvack.org (Postfix) with ESMTP id 3A4AC6B025E for ; Wed, 20 Dec 2017 10:56:02 -0500 (EST) Received: by mail-pl0-f69.google.com with SMTP id m39so8186892plg.19 for ; Wed, 20 Dec 2017 07:56:02 -0800 (PST) Received: from bombadil.infradead.org (bombadil.infradead.org. [65.50.211.133]) by mx.google.com with ESMTPS id t134si12081117pgc.384.2017.12.20.07.56.01 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 20 Dec 2017 07:56:01 -0800 (PST) From: Matthew Wilcox Subject: [PATCH v2 2/8] mm: De-indent struct page Date: Wed, 20 Dec 2017 07:55:46 -0800 Message-Id: <20171220155552.15884-3-willy@infradead.org> In-Reply-To: <20171220155552.15884-1-willy@infradead.org> References: <20171220155552.15884-1-willy@infradead.org> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: akpm@linuxfoundation.org, Matthew Wilcox From: Matthew Wilcox I found the struct { union { struct { union { struct { } } } } } layout rather confusing. Fortunately, there is an easier way to write this. The innermost union is of four things which are the size of an int, so the ones which are used by slab/slob/slub can be pulled up two levels to be in the outermost union with 'counters'. That leaves us with struct { union { struct { atomic_t; atomic_t; } } } which has the same layout, but is easier to read. Output from the current git version of pahole, diffed with -uw to ignore the whitespace changes from the indentation: @@ -11,9 +11,6 @@ }; /* 16 8 */ union { long unsigned int counters; /* 24 8 */ - struct { - union { - atomic_t _mapcount; /* 24 4 */ unsigned int active; /* 24 4 */ struct { unsigned int inuse:16; /* 24:16 4 */ @@ -21,7 +18,8 @@ unsigned int frozen:1; /* 24: 0 4 */ }; /* 24 4 */ int units; /* 24 4 */ - }; /* 24 4 */ + struct { + atomic_t _mapcount; /* 24 4 */ atomic_t _refcount; /* 28 4 */ }; /* 24 8 */ }; /* 24 8 */ Signed-off-by: Matthew Wilcox Acked-by: Kirill A. Shutemov Acked-by: Michal Hocko Acked-by: Christoph Lameter --- include/linux/mm_types.h | 40 +++++++++++++++++++--------------------- 1 file changed, 19 insertions(+), 21 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 4509f0cfaf39..27973166af28 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -84,28 +84,26 @@ struct page { */ unsigned counters; #endif - struct { + unsigned int active; /* SLAB */ + struct { /* SLUB */ + unsigned inuse:16; + unsigned objects:15; + unsigned frozen:1; + }; + int units; /* SLOB */ + + struct { /* Page cache */ + /* + * Count of ptes mapped in mms, to show when + * page is mapped & limit reverse map searches. + * + * Extra information about page type may be + * stored here for pages that are never mapped, + * in which case the value MUST BE <= -2. + * See page-flags.h for more details. + */ + atomic_t _mapcount; - union { - /* - * Count of ptes mapped in mms, to show when - * page is mapped & limit reverse map searches. - * - * Extra information about page type may be - * stored here for pages that are never mapped, - * in which case the value MUST BE <= -2. - * See page-flags.h for more details. - */ - atomic_t _mapcount; - - unsigned int active; /* SLAB */ - struct { /* SLUB */ - unsigned inuse:16; - unsigned objects:15; - unsigned frozen:1; - }; - int units; /* SLOB */ - }; /* * Usage count, *USE WRAPPER FUNCTION* when manual * accounting. See page_ref.h -- 2.15.1 -- 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