linux/arch/alpha
Hao Ge 59b5ed409d mm/percpu: conditionally define _shared_alloc_tag via CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU
Recently discovered this entry while checking kallsyms on ARM64:
ffff800083e509c0 D _shared_alloc_tag

If ARCH_NEEDS_WEAK_PER_CPU is not defined(it is only defined for s390 and
alpha architectures), there's no need to statically define the percpu
variable _shared_alloc_tag.

Therefore, we need to implement isolation for this purpose.

When building the core kernel code for s390 or alpha architectures,
ARCH_NEEDS_WEAK_PER_CPU remains undefined (as it is gated by #if
defined(MODULE)).  However, when building modules for these architectures,
the macro is explicitly defined.

Therefore, we remove all instances of ARCH_NEEDS_WEAK_PER_CPU from the
code and introduced CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU to replace the
relevant logic.  We can now conditionally define the perpcu variable
_shared_alloc_tag based on CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU.  This
allows architectures (such as s390/alpha) that require weak definitions
for percpu variables in modules to include the definition, while others
can omit it via compile-time exclusion.

Link: https://lkml.kernel.org/r/20250618015809.1235761-1-hao.ge@linux.dev
Signed-off-by: Hao Ge <gehao@kylinos.cn>
Suggested-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>	[s390]
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Chistoph Lameter <cl@linux.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-09 22:42:15 -07:00
..
boot alpha/boot/misc: trim unused declarations 2023-02-24 23:14:22 -05:00
configs reiserfs: The last commit 2024-10-21 16:29:38 +02:00
include mm/percpu: conditionally define _shared_alloc_tag via CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU 2025-07-09 22:42:15 -07:00
kernel treewide, timers: Rename from_timer() to timer_container_of() 2025-06-08 09:07:37 +02:00
lib alpha: remove duplicate included header file 2025-01-12 20:21:07 -08:00
math-emu alpha: missing includes 2024-05-03 22:09:30 +02:00
mm arch, mm: make releasing of memory to page allocator more explicit 2025-03-17 22:06:53 -07:00
Kbuild kbuild: use more subdir- for visiting subdirectories while cleaning 2021-10-24 13:49:46 +09:00
Kconfig mm/percpu: conditionally define _shared_alloc_tag via CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU 2025-07-09 22:42:15 -07:00
Kconfig.debug treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile alpha: drop pre-EV56 support 2024-05-06 12:05:00 +02:00