[RFC][PATCH 03/24] kernel/sched: Move thread stack to its own structure

[Dave Hansen]

Right now, the thread stack is directly declared in 'thread_union'.
There is shortly going to be more than one stack. Give all the stacks
their own structure instead of declaring *a* stack directly.

---

 b/include/linux/sched.h |    6 +++++-
 b/mm/kasan/report.c     |    6 +++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff -puN include/linux/sched.h~alloc_thread_stack_node-3 include/linux/sched.h
--- a/include/linux/sched.h~alloc_thread_stack_node-3	2026-10-21 12:36:33.575872729 -0700
+++ b/include/linux/sched.h	2026-10-21 12:36:33.613872802 -0700
@@ -1986,12 +1986,16 @@ extern void ia64_set_curr_task(int cpu,
 
 void yield(void);
 
+struct thread_stacks {
+	unsigned long stack[THREAD_SIZE/sizeof(long)];
+};
+
 union thread_union {
 	struct task_struct task;
 #ifndef CONFIG_THREAD_INFO_IN_TASK
 	struct thread_info thread_info;
 #endif
-	unsigned long stack[THREAD_SIZE/sizeof(long)];
+	struct thread_stacks stacks;
 };
 
 #ifndef CONFIG_THREAD_INFO_IN_TASK
diff -puN mm/kasan/report.c~alloc_thread_stack_node-3 mm/kasan/report.c
--- a/mm/kasan/report.c~alloc_thread_stack_node-3	2026-10-21 12:36:33.610872797 -0700
+++ b/mm/kasan/report.c	2026-10-21 12:36:33.613872802 -0700
@@ -365,9 +365,9 @@ static inline bool kernel_or_module_addr
 
 static inline bool init_task_stack_addr(const void *addr)
 {
-	return addr >= (void *)&init_thread_union.stack &&
-		(addr <= (void *)&init_thread_union.stack +
-			sizeof(init_thread_union.stack));
+	return addr >= (void *)&init_thread_union.stacks.stack &&
+		(addr <= (void *)&init_thread_union.stacks.stack +
+			sizeof(init_thread_union.stacks.stack));
 }
 
 static void print_address_description(void *addr, u8 tag,
_