* [PATCH] slab: work around clang bug #42570
@ 2019-07-12 9:04 Arnd Bergmann
2019-07-12 17:30 ` David Rientjes
0 siblings, 1 reply; 2+ messages in thread
From: Arnd Bergmann @ 2019-07-12 9:04 UTC (permalink / raw)
To: Christoph Lameter, Pekka Enberg, David Rientjes, Joonsoo Kim,
Andrew Morton
Cc: Arnd Bergmann, Stephen Rothwell, Roman Gushchin, Shakeel Butt,
Vladimir Davydov, Andrey Konovalov, linux-mm, linux-kernel,
clang-built-linux
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
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
We might decide to wait until this is fixed in clang, but
so far all versions targetting x86 seem to be affected.
---
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 6c49dbb3769e..807490fe217a 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1028,7 +1028,8 @@ 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);
/*
--
2.20.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] slab: work around clang bug #42570
2019-07-12 9:04 [PATCH] slab: work around clang bug #42570 Arnd Bergmann
@ 2019-07-12 17:30 ` David Rientjes
0 siblings, 0 replies; 2+ messages in thread
From: David Rientjes @ 2019-07-12 17:30 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Christoph Lameter, Pekka Enberg, Joonsoo Kim, Andrew Morton,
Stephen Rothwell, Roman Gushchin, Shakeel Butt, Vladimir Davydov,
Andrey Konovalov, linux-mm, linux-kernel, clang-built-linux
On Fri, 12 Jul 2019, Arnd Bergmann wrote:
> 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
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Rientjes <rientjes@google.com>
Let me followup on the clang bug as well.
^ permalink raw reply [flat|nested] 2+ messages in thread
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