slab: work around clang bug #42570
diff mbox series

Message ID 20190712090455.266021-1-arnd@arndb.de
State New
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Series
  • slab: work around clang bug #42570
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Commit Message

Arnd Bergmann July 12, 2019, 9:04 a.m. UTC
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(-)

Comments

David Rientjes July 12, 2019, 5:30 p.m. UTC | #1
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.

Patch
diff mbox series

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);
 
 /*