com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index f5ff6e84a9b7..17b5f3415465 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -74,10 +74,10 @@ struct mm_struct efi_mm = {
 	.page_table_lock	= __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
 	.mmlist			= LIST_HEAD_INIT(efi_mm.mmlist),
 	.user_ns		= &init_user_ns,
-	.cpu_bitmap		= { [BITS_TO_LONGS(NR_CPUS)] = 0},
 #ifdef CONFIG_SCHED_MM_CID
 	.mm_cid.lock		= __RAW_SPIN_LOCK_UNLOCKED(efi_mm.mm_cid.lock),
 #endif
+	.flexible_array		= MM_STRUCT_FLEXIBLE_ARRAY_INIT,
 };
 
 struct workqueue_struct *efi_rts_wq;
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 42af2292951d..110b319a2ffb 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -1329,7 +1329,7 @@ struct mm_struct {
 	 * The mm_cpumask needs to be at the end of mm_struct, because it
 	 * is dynamically sized based on nr_cpu_ids.
 	 */
-	unsigned long cpu_bitmap[];
+	char flexible_array[] __aligned(__alignof__(unsigned long));
 };
 
 /* Copy value to the first system word of mm flags, non-atomically. */
@@ -1366,19 +1366,24 @@ static inline void __mm_flags_set_mask_bits_word(struct mm_struct *mm,
 			 MT_FLAGS_USE_RCU)
 extern struct mm_struct init_mm;
 
+#define MM_STRUCT_FLEXIBLE_ARRAY_INIT				\
+{								\
+	[0 ... sizeof(cpumask_t)-1] = 0				\
+}
+
 /* Pointer magic because the dynamic array size confuses some compilers. */
 static inline void mm_init_cpumask(struct mm_struct *mm)
 {
 	unsigned long cpu_bitmap = (unsigned long)mm;
 
-	cpu_bitmap += offsetof(struct mm_struct, cpu_bitmap);
+	cpu_bitmap += offsetof(struct mm_struct, flexible_array);
 	cpumask_clear((struct cpumask *)cpu_bitmap);
 }
 
 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
 static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
 {
-	return (struct cpumask *)&mm->cpu_bitmap;
+	return (struct cpumask *)&mm->flexible_array;
 }
 
 #ifdef CONFIG_LRU_GEN
@@ -1469,7 +1474,7 @@ static inline cpumask_t *mm_cpus_allowed(struct mm_struct *mm)
 {
 	unsigned long bitmap = (unsigned long)mm;
 
-	bitmap += offsetof(struct mm_struct, cpu_bitmap);
+	bitmap += offsetof(struct mm_struct, flexible_array);
 	/* Skip cpu_bitmap */
 	bitmap += cpumask_size();
 	return (struct cpumask *)bitmap;
diff --git a/mm/init-mm.c b/mm/init-mm.c
index a514f8ce47e3..c5556bb9d5f0 100644
--- a/mm/init-mm.c
+++ b/mm/init-mm.c
@@ -47,7 +47,7 @@ struct mm_struct init_mm = {
 #ifdef CONFIG_SCHED_MM_CID
 	.mm_cid.lock = __RAW_SPIN_LOCK_UNLOCKED(init_mm.mm_cid.lock),
 #endif
-	.cpu_bitmap	= CPU_BITS_NONE,
+	.flexible_array	= MM_STRUCT_FLEXIBLE_ARRAY_INIT,
 	INIT_MM_CONTEXT(init_mm)
 };
 FAILED: patch "[PATCH] mm: rename cpu_bitmap field to flexible_array" failed to apply to 6.6-stable tree<gregkh@linuxfoundation.org> undefinedmathieu.desnoyers@efficios.com,aboorvad@linux.ibm.com,akpm@linux-foundation.org,baolin.wang@linux.alibaba.com,brauner@kernel.org,broonie@kernel.org,christian.koenig@amd.com,cl@linux.com,david@redhat.com,dennis@kernel.org,hannes@cmpxchg.org,liam.howlett@oracle.com,linmiaohe@huawei.com,liumartin@google.com,lorenzo.stoakes@oracle.com,mhiramat@kernel.org,mhocko@suse.com,mjguzik@gmail.com,paulmck@kernel.org,peterz@infradead.org,richard.weiyang@gmail.com,rientjes@google.com,roman.gushchin@linux.dev,rostedt@goodmis.org,rppt@kernel.org,shakeel.butt@linux.dev,sj@kernel.org,stable@vger.kernel.org,surenb@google.com,sweettea-kernel@dorminy.me,tglx@kernel.org,tj@kernel.org,vbabka@suse.cz,viro@zeniv.linux.org.uk,willy@infradead.org,yuzhao@google.com undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined