From ea6bd8ee1a2ccdffc38b2b1fcfe941addfafaade Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 6 Jul 2011 09:46:18 -0500 Subject: [PATCH] SLUB: Fix build breakage in linux/mm_types.h On Wed, 6 Jul 2011, Jonathan Cameron wrote: > Getting: > > CHK include/linux/version.h > CHK include/generated/utsrelease.h > make[1]: `include/generated/mach-types.h' is up to date. > CC arch/arm/kernel/asm-offsets.s > In file included from include/linux/sched.h:64:0, > from arch/arm/kernel/asm-offsets.c:13: > include/linux/mm_types.h:74:15: error: duplicate member '_count' > make[1]: *** [arch/arm/kernel/asm-offsets.s] Error 1 > make: *** [prepare0] Error 2 > > Issue looks to have been introduced by > > mm: Rearrange struct page > > fc9bb8c768abe7ae10861c3510e01a95f98d5933 > > Guessing it's a known issue, but just thought I'd flag it up in case > it's something very specific about my build. > > gcc-2.6 armv7a > > Reverting that patch works, but given I don't know the history, I'm > not proposing doing that in general! Well _count exists in two unionized structs but always has the same offset within the larger struct. Maybe ARM creates different offsets there for some reason? The following is a patch to restructure the union / structs combo in such a way that only a single definition of _count Reported-by: Jonathan Cameron Tested-by: Piotr Hosowicz Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg --- include/linux/mm_types.h | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3d76a433d52f..6dc6413f5deb 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -49,32 +49,27 @@ struct page { * see PAGE_MAPPING_ANON below. */ /* Second double word */ - union { - struct { + struct { + union { pgoff_t index; /* Our offset within mapping. */ + void *freelist; /* slub first free object */ + }; + + union { atomic_t _mapcount; /* Count of ptes mapped in mms, * to show when page is mapped * & limit reverse map searches. */ - atomic_t _count; /* Usage count, see below. */ - }; - struct { /* SLUB cmpxchg_double area */ - void *freelist; - union { - unsigned long counters; - struct { + /* Used for cmpxchg_double in slub */ + unsigned long counters; + struct { unsigned inuse:16; unsigned objects:15; unsigned frozen:1; - /* - * Kernel may make use of this field even when slub - * uses the rest of the double word! - */ - atomic_t _count; - }; }; }; + atomic_t _count; /* Usage count, see below. */ }; /* Third double word block */ -- 2.20.1