On 2/1/22 14:34, Andrew Morton wrote:
The patch titled
Subject: mm/sparsemem: fix 'mem_section' will never be NULL gcc 12 warning
has been added to the -mm tree. Its filename is
mm-sparsemem-fix-mem_section-will-never-be-null-gcc-12-warning.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-sparsemem-fix-mem_section-will-never-be-null-gcc-12-warning.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-sparsemem-fix-mem_section-will-never-be-null-gcc-12-warning.patch
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------------------------------------------------------
From: Waiman Long <longman@xxxxxxxxxx>
Subject: mm/sparsemem: fix 'mem_section' will never be NULL gcc 12 warning
The gcc 12 compiler reports a warning on the following code:
static inline struct mem_section *__nr_to_section(unsigned long nr)
{
#ifdef CONFIG_SPARSEMEM_EXTREME
if (!mem_section)
return NULL;
#endif
:
With CONFIG_SPARSEMEM_EXTREME on, the mem_section definition is
extern struct mem_section **mem_section;
Obviously, mem_section cannot be NULL, but *mem_section can be if memory
hasn't been allocated for the dynamic mem_section[] array yet. Fix this
warning by checking for "!*mem_section" instead.
Link: https://lkml.kernel.org/r/20220201192924.672675-1-longman@xxxxxxxxxx
Fixes: 83e3c48729d9 ("mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y")
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Justin Forbes <jforbes@xxxxxxxxxx>
Cc: Rafael Aquini <aquini@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/linux/mmzone.h~mm-sparsemem-fix-mem_section-will-never-be-null-gcc-12-warning
+++ a/include/linux/mmzone.h
@@ -1390,7 +1390,7 @@ static inline unsigned long *section_to_
static inline struct mem_section *__nr_to_section(unsigned long nr)
{
#ifdef CONFIG_SPARSEMEM_EXTREME
- if (!mem_section)
+ if (!*mem_section)
return NULL;
#endif
if (!mem_section[SECTION_NR_TO_ROOT(nr)])
_
Patches currently in -mm which might be from longman@xxxxxxxxxx are
mm-sparsemem-fix-mem_section-will-never-be-null-gcc-12-warning.patch
ipc-mqueue-use-get_tree_nodev-in-mqueue_get_tree.patch
Sorry, this patch isn't complete. I will send out a v2 soon.
Thanks,
Longman
