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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
        David Rientjes <rientjes@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Roman Gushchin <guro@fb.com>,
        Shakeel Butt <shakeelb@google.com>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.2 048/131] mm/slab_common.c: work around clang bug #42570
Date:   Mon,  5 Aug 2019 15:02:15 +0200
Message-Id: <20190805124954.649146552@linuxfoundation.org>
In-Reply-To: <20190805124951.453337465@linuxfoundation.org>
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[ Upstream commit a07057dce2823e10d64a2b73cefbf09d8645efe9 ]

Clang gets rather confused about two variables in the same special
section when one of them is not initialized, leading to an assembler
warning later:

  /tmp/slab_common-18f869.s: Assembler messages:
  /tmp/slab_common-18f869.s:7526: Warning: ignoring changed section attributes for .data..ro_after_init

Adding an initialization to kmalloc_caches is rather silly here
but does avoid the issue.

Link: https://bugs.llvm.org/show_bug.cgi?id=42570
Link: http://lkml.kernel.org/r/20190712090455.266021-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/slab_common.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 58251ba63e4a1..cbd3411f644e4 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1003,7 +1003,8 @@ struct kmem_cache *__init create_kmalloc_cache(const char *name,
 }
 
 struct kmem_cache *
-kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init;
+kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init =
+{ /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ };
 EXPORT_SYMBOL(kmalloc_caches);
 
 /*
-- 
2.20.1