// SPDX-License-Identifier: GPL-2.0

  #include <linux/mm_types.h>
  #include <linux/rbtree.h>
  #include <linux/rwsem.h>
  #include <linux/spinlock.h>
  #include <linux/list.h>
  #include <linux/cpumask.h>

  #include <linux/atomic.h>

  #include <linux/user_namespace.h>

  #include <asm/pgtable.h>

  #include <asm/mmu.h>
  
  #ifndef INIT_MM_CONTEXT
  #define INIT_MM_CONTEXT(name)
  #endif

  /*
   * For dynamically allocated mm_structs, there is a dynamically sized cpumask
   * at the end of the structure, the size of which depends on the maximum CPU
   * number the system can see. That way we allocate only as much memory for
   * mm_cpumask() as needed for the hundreds, or thousands of processes that
   * a system typically runs.
   *
   * Since there is only one init_mm in the entire system, keep it simple
   * and size this cpu_bitmask to NR_CPUS.
   */

  struct mm_struct init_mm = {
  	.mm_rb		= RB_ROOT,
  	.pgd		= swapper_pg_dir,
  	.mm_users	= ATOMIC_INIT(2),
  	.mm_count	= ATOMIC_INIT(1),
  	.mmap_sem	= __RWSEM_INITIALIZER(init_mm.mmap_sem),
  	.page_table_lock =  __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock),

  	.arg_lock	=  __SPIN_LOCK_UNLOCKED(init_mm.arg_lock),

  	.mmlist		= LIST_HEAD_INIT(init_mm.mmlist),

  	.user_ns	= &init_user_ns,

  	.cpu_bitmap	= { [BITS_TO_LONGS(NR_CPUS)] = 0},

  	INIT_MM_CONTEXT(init_mm)

  };