sched/headers: Move task->mm handling methods to <linux/sched/mm.h>

Move the following task->mm helper APIs into a new header file,
<linux/sched/mm.h>, to further reduce the size and complexity
of <linux/sched.h>.

Here are how the APIs are used in various kernel files:

  # mm_alloc():
  arch/arm/mach-rpc/ecard.c
  fs/exec.c
  include/linux/sched/mm.h
  kernel/fork.c

  # __mmdrop():
  arch/arc/include/asm/mmu_context.h
  include/linux/sched/mm.h
  kernel/fork.c

  # mmdrop():
  arch/arm/mach-rpc/ecard.c
  arch/m68k/sun3/mmu_emu.c
  arch/x86/mm/tlb.c
  drivers/gpu/drm/amd/amdkfd/kfd_process.c
  drivers/gpu/drm/i915/i915_gem_userptr.c
  drivers/infiniband/hw/hfi1/file_ops.c
  drivers/vfio/vfio_iommu_spapr_tce.c
  fs/exec.c
  fs/proc/base.c
  fs/proc/task_mmu.c
  fs/proc/task_nommu.c
  fs/userfaultfd.c
  include/linux/mmu_notifier.h
  include/linux/sched/mm.h
  kernel/fork.c
  kernel/futex.c
  kernel/sched/core.c
  mm/khugepaged.c
  mm/ksm.c
  mm/mmu_context.c
  mm/mmu_notifier.c
  mm/oom_kill.c
  virt/kvm/kvm_main.c

  # mmdrop_async_fn():
  include/linux/sched/mm.h

  # mmdrop_async():
  include/linux/sched/mm.h
  kernel/fork.c

  # mmget_not_zero():
  fs/userfaultfd.c
  include/linux/sched/mm.h
  mm/oom_kill.c

  # mmput():
  arch/arc/include/asm/mmu_context.h
  arch/arc/kernel/troubleshoot.c
  arch/frv/mm/mmu-context.c
  arch/powerpc/platforms/cell/spufs/context.c
  arch/sparc/include/asm/mmu_context_32.h
  drivers/android/binder.c
  drivers/gpu/drm/etnaviv/etnaviv_gem.c
  drivers/gpu/drm/i915/i915_gem_userptr.c
  drivers/infiniband/core/umem.c
  drivers/infiniband/core/umem_odp.c
  drivers/infiniband/core/uverbs_main.c
  drivers/infiniband/hw/mlx4/main.c
  drivers/infiniband/hw/mlx5/main.c
  drivers/infiniband/hw/usnic/usnic_uiom.c
  drivers/iommu/amd_iommu_v2.c
  drivers/iommu/intel-svm.c
  drivers/lguest/lguest_user.c
  drivers/misc/cxl/fault.c
  drivers/misc/mic/scif/scif_rma.c
  drivers/oprofile/buffer_sync.c
  drivers/vfio/vfio_iommu_type1.c
  drivers/vhost/vhost.c
  drivers/xen/gntdev.c
  fs/exec.c
  fs/proc/array.c
  fs/proc/base.c
  fs/proc/task_mmu.c
  fs/proc/task_nommu.c
  fs/userfaultfd.c
  include/linux/sched/mm.h
  kernel/cpuset.c
  kernel/events/core.c
  kernel/events/uprobes.c
  kernel/exit.c
  kernel/fork.c
  kernel/ptrace.c
  kernel/sys.c
  kernel/trace/trace_output.c
  kernel/tsacct.c
  mm/memcontrol.c
  mm/memory.c
  mm/mempolicy.c
  mm/migrate.c
  mm/mmu_notifier.c
  mm/nommu.c
  mm/oom_kill.c
  mm/process_vm_access.c
  mm/rmap.c
  mm/swapfile.c
  mm/util.c
  virt/kvm/async_pf.c

  # mmput_async():
  include/linux/sched/mm.h
  kernel/fork.c
  mm/oom_kill.c

  # get_task_mm():
  arch/arc/kernel/troubleshoot.c
  arch/powerpc/platforms/cell/spufs/context.c
  drivers/android/binder.c
  drivers/gpu/drm/etnaviv/etnaviv_gem.c
  drivers/infiniband/core/umem.c
  drivers/infiniband/core/umem_odp.c
  drivers/infiniband/hw/mlx4/main.c
  drivers/infiniband/hw/mlx5/main.c
  drivers/infiniband/hw/usnic/usnic_uiom.c
  drivers/iommu/amd_iommu_v2.c
  drivers/iommu/intel-svm.c
  drivers/lguest/lguest_user.c
  drivers/misc/cxl/fault.c
  drivers/misc/mic/scif/scif_rma.c
  drivers/oprofile/buffer_sync.c
  drivers/vfio/vfio_iommu_type1.c
  drivers/vhost/vhost.c
  drivers/xen/gntdev.c
  fs/proc/array.c
  fs/proc/base.c
  fs/proc/task_mmu.c
  include/linux/sched/mm.h
  kernel/cpuset.c
  kernel/events/core.c
  kernel/exit.c
  kernel/fork.c
  kernel/ptrace.c
  kernel/sys.c
  kernel/trace/trace_output.c
  kernel/tsacct.c
  mm/memcontrol.c
  mm/memory.c
  mm/mempolicy.c
  mm/migrate.c
  mm/mmu_notifier.c
  mm/nommu.c
  mm/util.c

  # mm_access():
  fs/proc/base.c
  include/linux/sched/mm.h
  kernel/fork.c
  mm/process_vm_access.c

  # mm_release():
  arch/arc/include/asm/mmu_context.h
  fs/exec.c
  include/linux/sched/mm.h
  include/uapi/linux/sched.h
  kernel/exit.c
  kernel/fork.c

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

26 files changed, 120 insertions, 116 deletions

diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index acb4b146a607..9fc560459ebd 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -14,7 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/kernel_stat.h>
 #include <linux/module.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/mm.h>
 #include <linux/err.h>
 #include <linux/threads.h>
diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
index b8e8d3944481..f46267153ec2 100644
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -13,7 +13,7 @@
  */
 
 #include <linux/spinlock.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/interrupt.h>
 #include <linux/profile.h>
 #include <linux/mm.h>
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index b724cff7ad60..572a8df1b766 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -11,7 +11,7 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/hotplug.h>
 #include <linux/sched/task_stack.h>
 #include <linux/interrupt.h>
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 83c0a839a6ad..ef1caae02110 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -21,7 +21,7 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/hotplug.h>
 #include <linux/sched/task_stack.h>
 #include <linux/interrupt.h>
diff --git a/arch/blackfin/mach-common/smp.c b/arch/blackfin/mach-common/smp.c
index 3ac98252d299..b32ddab7966c 100644
--- a/arch/blackfin/mach-common/smp.c
+++ b/arch/blackfin/mach-common/smp.c
@@ -11,7 +11,7 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/task_stack.h>
 #include <linux/interrupt.h>
 #include <linux/cache.h>
diff --git a/arch/hexagon/kernel/smp.c b/arch/hexagon/kernel/smp.c
index 1f63e91a353b..5dbc15549e01 100644
--- a/arch/hexagon/kernel/smp.c
+++ b/arch/hexagon/kernel/smp.c
@@ -25,7 +25,7 @@
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/percpu.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/smp.h>
 #include <linux/spinlock.h>
 #include <linux/cpu.h>
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 63bef6fc0f3e..23e3fd61e335 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -32,7 +32,7 @@
 #include <linux/cpu.h>
 #include <linux/kernel.h>
 #include <linux/reboot.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/clock.h>
 #include <linux/sched/task_stack.h>
 #include <linux/seq_file.h>
diff --git a/arch/m32r/kernel/setup.c b/arch/m32r/kernel/setup.c
index b18bc0bd6544..1a9e977287e6 100644
--- a/arch/m32r/kernel/setup.c
+++ b/arch/m32r/kernel/setup.c
@@ -11,7 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/stddef.h>
 #include <linux/fs.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/ioport.h>
 #include <linux/mm.h>
 #include <linux/bootmem.h>
diff --git a/arch/metag/kernel/smp.c b/arch/metag/kernel/smp.c
index cab2aa64ca82..232a12bf3f99 100644
--- a/arch/metag/kernel/smp.c
+++ b/arch/metag/kernel/smp.c
@@ -12,7 +12,7 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/hotplug.h>
 #include <linux/sched/task_stack.h>
 #include <linux/interrupt.h>
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 1a9366a157cb..c7d17cfb32f6 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -23,7 +23,7 @@
 #include <linux/module.h>
 #include <linux/extable.h>
 #include <linux/mm.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/debug.h>
 #include <linux/smp.h>
 #include <linux/spinlock.h>
diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c
index 67b452b41ff6..63365106ea19 100644
--- a/arch/parisc/kernel/smp.c
+++ b/arch/parisc/kernel/smp.c
@@ -21,7 +21,7 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/smp.h>
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index fce17789c675..46f89e66a273 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -19,7 +19,7 @@
 
 #include <linux/kernel.h>
 #include <linux/export.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/topology.h>
 #include <linux/smp.h>
 #include <linux/interrupt.h>
diff --git a/arch/s390/kernel/processor.c b/arch/s390/kernel/processor.c
index bf7854523831..928b929a6261 100644
--- a/arch/s390/kernel/processor.c
+++ b/arch/s390/kernel/processor.c
@@ -8,11 +8,13 @@
 
 #include <linux/cpufeature.h>
 #include <linux/kernel.h>
+#include <linux/sched/mm.h>
 #include <linux/init.h>
 #include <linux/seq_file.h>
 #include <linux/mm_types.h>
 #include <linux/delay.h>
 #include <linux/cpu.h>
+
 #include <asm/diag.h>
 #include <asm/facility.h>
 #include <asm/elf.h>
diff --git a/arch/score/kernel/traps.c b/arch/score/kernel/traps.c
index fe68de6c746c..e359ec675869 100644
--- a/arch/score/kernel/traps.c
+++ b/arch/score/kernel/traps.c
@@ -24,6 +24,7 @@
  */
 
 #include <linux/extable.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/debug.h>
 #include <linux/mm_types.h>
diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
index 4abf119c129c..c483422ea4d0 100644
--- a/arch/sh/kernel/smp.c
+++ b/arch/sh/kernel/smp.c
@@ -20,7 +20,7 @@
 #include <linux/module.h>
 #include <linux/cpu.h>
 #include <linux/interrupt.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/hotplug.h>
 #include <linux/atomic.h>
 #include <linux/clockchips.h>
diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
index b99d33797e1d..db7acf27bea2 100644
--- a/arch/sparc/kernel/leon_smp.c
+++ b/arch/sparc/kernel/leon_smp.c
@@ -9,7 +9,7 @@
 #include <asm/head.h>
 
 #include <linux/kernel.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/threads.h>
 #include <linux/smp.h>
 #include <linux/interrupt.h>
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 15052d364e04..b3bc0ac757cc 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -5,7 +5,7 @@
 
 #include <linux/export.h>
 #include <linux/kernel.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/hotplug.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
diff --git a/arch/sparc/kernel/sun4d_smp.c b/arch/sparc/kernel/sun4d_smp.c
index 7b55c50eabe5..af93b50e3ce4 100644
--- a/arch/sparc/kernel/sun4d_smp.c
+++ b/arch/sparc/kernel/sun4d_smp.c
@@ -10,7 +10,7 @@
 #include <linux/interrupt.h>
 #include <linux/profile.h>
 #include <linux/delay.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/cpu.h>
 
 #include <asm/cacheflush.h>
diff --git a/arch/sparc/kernel/sun4m_smp.c b/arch/sparc/kernel/sun4m_smp.c
index 633c4cf6fdb0..5547fcb1d72d 100644
--- a/arch/sparc/kernel/sun4m_smp.c
+++ b/arch/sparc/kernel/sun4m_smp.c
@@ -8,7 +8,7 @@
 #include <linux/interrupt.h>
 #include <linux/profile.h>
 #include <linux/delay.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/cpu.h>
 
 #include <asm/cacheflush.h>
diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
index 2de72a49308a..466d4aed06c7 100644
--- a/arch/sparc/kernel/traps_32.c
+++ b/arch/sparc/kernel/traps_32.c
@@ -9,7 +9,7 @@
  * I hate traps on the sparc, grrr...
  */
 
-#include <linux/sched.h>  /* for jiffies */
+#include <linux/sched/mm.h>
 #include <linux/sched/debug.h>
 #include <linux/mm_types.h>
 #include <linux/kernel.h>
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index 4ff4c35f76b2..196ee5eb4d48 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -9,7 +9,7 @@
  */
 
 #include <linux/extable.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/debug.h>
 #include <linux/linkage.h>
 #include <linux/kernel.h>
diff --git a/arch/tile/kernel/smpboot.c b/arch/tile/kernel/smpboot.c
index f3fdd0c39b12..869c22e57561 100644
--- a/arch/tile/kernel/smpboot.c
+++ b/arch/tile/kernel/smpboot.c
@@ -16,7 +16,7 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/task.h>
 #include <linux/kernel_stat.h>
 #include <linux/bootmem.h>
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index f2fd8fefc589..b11b38c3b0bd 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -7,7 +7,7 @@
 #include <linux/string.h>
 #include <linux/ctype.h>
 #include <linux/delay.h>
-#include <linux/sched.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/clock.h>
 #include <linux/sched/task.h>
 #include <linux/init.h>
diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c
index fd894eaa63f3..932d64689bac 100644
--- a/arch/xtensa/kernel/smp.c
+++ b/arch/xtensa/kernel/smp.c
@@ -21,6 +21,7 @@
 #include <linux/irq.h>
 #include <linux/kdebug.h>
 #include <linux/module.h>
+#include <linux/sched/mm.h>
 #include <linux/sched/hotplug.h>
 #include <linux/sched/task_stack.h>
 #include <linux/reboot.h>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 042620729230..d29bbe0ee41f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2379,101 +2379,6 @@ static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
 	return sp;
 }
 
-/*
- * Routines for handling mm_structs
- */
-extern struct mm_struct * mm_alloc(void);
-
-/**
- * mmgrab() - Pin a &struct mm_struct.
- * @mm: The &struct mm_struct to pin.
- *
- * Make sure that @mm will not get freed even after the owning task
- * exits. This doesn't guarantee that the associated address space
- * will still exist later on and mmget_not_zero() has to be used before
- * accessing it.
- *
- * This is a preferred way to to pin @mm for a longer/unbounded amount
- * of time.
- *
- * Use mmdrop() to release the reference acquired by mmgrab().
- *
- * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
- * of &mm_struct.mm_count vs &mm_struct.mm_users.
- */
-static inline void mmgrab(struct mm_struct *mm)
-{
-	atomic_inc(&mm->mm_count);
-}
-
-/* mmdrop drops the mm and the page tables */
-extern void __mmdrop(struct mm_struct *);
-static inline void mmdrop(struct mm_struct *mm)
-{
-	if (unlikely(atomic_dec_and_test(&mm->mm_count)))
-		__mmdrop(mm);
-}
-
-static inline void mmdrop_async_fn(struct work_struct *work)
-{
-	struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work);
-	__mmdrop(mm);
-}
-
-static inline void mmdrop_async(struct mm_struct *mm)
-{
-	if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
-		INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
-		schedule_work(&mm->async_put_work);
-	}
-}
-
-/**
- * mmget() - Pin the address space associated with a &struct mm_struct.
- * @mm: The address space to pin.
- *
- * Make sure that the address space of the given &struct mm_struct doesn't
- * go away. This does not protect against parts of the address space being
- * modified or freed, however.
- *
- * Never use this function to pin this address space for an
- * unbounded/indefinite amount of time.
- *
- * Use mmput() to release the reference acquired by mmget().
- *
- * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
- * of &mm_struct.mm_count vs &mm_struct.mm_users.
- */
-static inline void mmget(struct mm_struct *mm)
-{
-	atomic_inc(&mm->mm_users);
-}
-
-static inline bool mmget_not_zero(struct mm_struct *mm)
-{
-	return atomic_inc_not_zero(&mm->mm_users);
-}
-
-/* mmput gets rid of the mappings and all user-space */
-extern void mmput(struct mm_struct *);
-#ifdef CONFIG_MMU
-/* same as above but performs the slow path from the async context. Can
- * be called from the atomic context as well
- */
-extern void mmput_async(struct mm_struct *);
-#endif
-
-/* Grab a reference to a task's mm, if it is not already going away */
-extern struct mm_struct *get_task_mm(struct task_struct *task);
-/*
- * Grab a reference to a task's mm, if it is not already going away
- * and ptrace_may_access with the mode parameter passed to it
- * succeeds.
- */
-extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
-/* Remove the current tasks stale references to the old mm_struct */
-extern void mm_release(struct task_struct *, struct mm_struct *);
-
 #ifdef CONFIG_HAVE_COPY_THREAD_TLS
 extern int copy_thread_tls(unsigned long, unsigned long, unsigned long,
 			struct task_struct *, unsigned long);
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index d32e3932b2e3..be1ae55f5ab9 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -5,4 +5,99 @@
 #include <linux/mm_types.h>
 #include <linux/gfp.h>
 
+/*
+ * Routines for handling mm_structs
+ */
+extern struct mm_struct * mm_alloc(void);
+
+/**
+ * mmgrab() - Pin a &struct mm_struct.
+ * @mm: The &struct mm_struct to pin.
+ *
+ * Make sure that @mm will not get freed even after the owning task
+ * exits. This doesn't guarantee that the associated address space
+ * will still exist later on and mmget_not_zero() has to be used before
+ * accessing it.
+ *
+ * This is a preferred way to to pin @mm for a longer/unbounded amount
+ * of time.
+ *
+ * Use mmdrop() to release the reference acquired by mmgrab().
+ *
+ * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
+ * of &mm_struct.mm_count vs &mm_struct.mm_users.
+ */
+static inline void mmgrab(struct mm_struct *mm)
+{
+	atomic_inc(&mm->mm_count);
+}
+
+/* mmdrop drops the mm and the page tables */
+extern void __mmdrop(struct mm_struct *);
+static inline void mmdrop(struct mm_struct *mm)
+{
+	if (unlikely(atomic_dec_and_test(&mm->mm_count)))
+		__mmdrop(mm);
+}
+
+static inline void mmdrop_async_fn(struct work_struct *work)
+{
+	struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work);
+	__mmdrop(mm);
+}
+
+static inline void mmdrop_async(struct mm_struct *mm)
+{
+	if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
+		INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
+		schedule_work(&mm->async_put_work);
+	}
+}
+
+/**
+ * mmget() - Pin the address space associated with a &struct mm_struct.
+ * @mm: The address space to pin.
+ *
+ * Make sure that the address space of the given &struct mm_struct doesn't
+ * go away. This does not protect against parts of the address space being
+ * modified or freed, however.
+ *
+ * Never use this function to pin this address space for an
+ * unbounded/indefinite amount of time.
+ *
+ * Use mmput() to release the reference acquired by mmget().
+ *
+ * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
+ * of &mm_struct.mm_count vs &mm_struct.mm_users.
+ */
+static inline void mmget(struct mm_struct *mm)
+{
+	atomic_inc(&mm->mm_users);
+}
+
+static inline bool mmget_not_zero(struct mm_struct *mm)
+{
+	return atomic_inc_not_zero(&mm->mm_users);
+}
+
+/* mmput gets rid of the mappings and all user-space */
+extern void mmput(struct mm_struct *);
+#ifdef CONFIG_MMU
+/* same as above but performs the slow path from the async context. Can
+ * be called from the atomic context as well
+ */
+extern void mmput_async(struct mm_struct *);
+#endif
+
+/* Grab a reference to a task's mm, if it is not already going away */
+extern struct mm_struct *get_task_mm(struct task_struct *task);
+/*
+ * Grab a reference to a task's mm, if it is not already going away
+ * and ptrace_may_access with the mode parameter passed to it
+ * succeeds.
+ */
+extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
+/* Remove the current tasks stale references to the old mm_struct */
+extern void mm_release(struct task_struct *, struct mm_struct *);
+
 #endif /* _LINUX_SCHED_MM_H */