[PATCH 1/4] mm: add new mmgrab() helper

From: Vegard Nossum
Date: Sun Dec 18 2016 - 07:34:41 EST

Apart from adding the helper function itself, the rest of the kernel is
converted mechanically using:

git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)->mm_count);/mmgrab\(\1\);/'
git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)\.mm_count);/mmgrab\(\&\1\);/'

This is needed for a later patch that hooks into the helper, but might be
a worthwhile cleanup on its own.

(Michal Hocko provided most of the kerneldoc comment.)

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
---
arch/alpha/kernel/smp.c | 2 +-
arch/arc/kernel/smp.c | 2 +-
arch/arm/kernel/smp.c | 2 +-
arch/arm64/kernel/smp.c | 2 +-
arch/blackfin/mach-common/smp.c | 2 +-
arch/hexagon/kernel/smp.c | 2 +-
arch/ia64/kernel/setup.c | 2 +-
arch/m32r/kernel/setup.c | 2 +-
arch/metag/kernel/smp.c | 2 +-
arch/mips/kernel/traps.c | 2 +-
arch/mn10300/kernel/smp.c | 2 +-
arch/parisc/kernel/smp.c | 2 +-
arch/powerpc/kernel/smp.c | 2 +-
arch/s390/kernel/processor.c | 2 +-
arch/score/kernel/traps.c | 2 +-
arch/sh/kernel/smp.c | 2 +-
arch/sparc/kernel/leon_smp.c | 2 +-
arch/sparc/kernel/smp_64.c | 2 +-
arch/sparc/kernel/sun4d_smp.c | 2 +-
arch/sparc/kernel/sun4m_smp.c | 2 +-
arch/sparc/kernel/traps_32.c | 2 +-
arch/sparc/kernel/traps_64.c | 2 +-
arch/tile/kernel/smpboot.c | 2 +-
arch/x86/kernel/cpu/common.c | 4 ++--
arch/xtensa/kernel/smp.c | 2 +-
drivers/gpu/drm/amd/amdkfd/kfd_process.c | 2 +-
drivers/gpu/drm/i915/i915_gem_userptr.c | 2 +-
drivers/infiniband/hw/hfi1/file_ops.c | 2 +-
fs/proc/base.c | 4 ++--
fs/userfaultfd.c | 2 +-
include/linux/sched.h | 22 ++++++++++++++++++++++
kernel/exit.c | 2 +-
kernel/futex.c | 2 +-
kernel/sched/core.c | 4 ++--
mm/khugepaged.c | 2 +-
mm/ksm.c | 2 +-
mm/mmu_context.c | 2 +-
mm/mmu_notifier.c | 2 +-
mm/oom_kill.c | 4 ++--
virt/kvm/kvm_main.c | 2 +-
40 files changed, 65 insertions(+), 43 deletions(-)

diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 46bf263c3153..acb4b146a607 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -144,7 +144,7 @@ smp_callin(void)
alpha_mv.smp_callin();

/* All kernel threads share the same mm context. */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;

/* inform the notifiers about the new cpu */
diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
index 88674d972c9d..9cbc7aba3ede 100644
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -125,7 +125,7 @@ void start_kernel_secondary(void)
setup_processor();

atomic_inc(&mm->mm_users);
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 7dd14e8395e6..c6514ce0fcbc 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -371,7 +371,7 @@ asmlinkage void secondary_start_kernel(void)
* reference and switch to it.
*/
cpu = smp_processor_id();
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index cb87234cfcf2..959e41196cba 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -222,7 +222,7 @@ asmlinkage void secondary_start_kernel(void)
* All kernel threads share the same mm context; grab a
* reference and switch to it.
*/
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
current->active_mm = mm;

/*
diff --git a/arch/blackfin/mach-common/smp.c b/arch/blackfin/mach-common/smp.c
index 23c4ef5f8bdc..bc5617ef7128 100644
--- a/arch/blackfin/mach-common/smp.c
+++ b/arch/blackfin/mach-common/smp.c
@@ -308,7 +308,7 @@ void secondary_start_kernel(void)

/* Attach the new idle task to the global mm. */
atomic_inc(&mm->mm_users);
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
current->active_mm = mm;

preempt_disable();
diff --git a/arch/hexagon/kernel/smp.c b/arch/hexagon/kernel/smp.c
index 983bae7d2665..c02a6455839e 100644
--- a/arch/hexagon/kernel/smp.c
+++ b/arch/hexagon/kernel/smp.c
@@ -162,7 +162,7 @@ void start_secondary(void)
);

/* Set the memory struct */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;

cpu = smp_processor_id();
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 7ec7acc844c2..ecbff47b01f1 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -992,7 +992,7 @@ cpu_init (void)
*/
ia64_setreg(_IA64_REG_CR_DCR, ( IA64_DCR_DP | IA64_DCR_DK | IA64_DCR_DX | IA64_DCR_DR
| IA64_DCR_DA | IA64_DCR_DD | IA64_DCR_LC));
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;
BUG_ON(current->mm);

diff --git a/arch/m32r/kernel/setup.c b/arch/m32r/kernel/setup.c
index 136c69f1fb8a..b18bc0bd6544 100644
--- a/arch/m32r/kernel/setup.c
+++ b/arch/m32r/kernel/setup.c
@@ -403,7 +403,7 @@ void __init cpu_init (void)
printk(KERN_INFO "Initializing CPU#%d\n", cpu_id);

/* Set up and load the per-CPU TSS and LDT */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;
if (current->mm)
BUG();
diff --git a/arch/metag/kernel/smp.c b/arch/metag/kernel/smp.c
index bad13232de51..af9cff547a19 100644
--- a/arch/metag/kernel/smp.c
+++ b/arch/metag/kernel/smp.c
@@ -345,7 +345,7 @@ asmlinkage void secondary_start_kernel(void)
* reference and switch to it.
*/
atomic_inc(&mm->mm_users);
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));
enter_lazy_tlb(mm, current);
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 3905003dfe2b..e50b0e0ca44c 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -2177,7 +2177,7 @@ void per_cpu_trap_init(bool is_boot_cpu)
if (!cpu_data[cpu].asid_cache)
cpu_data[cpu].asid_cache = asid_first_version(cpu);

- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;
BUG_ON(current->mm);
enter_lazy_tlb(&init_mm, current);
diff --git a/arch/mn10300/kernel/smp.c b/arch/mn10300/kernel/smp.c
index 426173c4b0b9..e65b5cc2fa67 100644
--- a/arch/mn10300/kernel/smp.c
+++ b/arch/mn10300/kernel/smp.c
@@ -589,7 +589,7 @@ static void __init smp_cpu_init(void)
}
printk(KERN_INFO "Initializing CPU#%d\n", cpu_id);

- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;
BUG_ON(current->mm);

diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c
index 75dab2871346..67b452b41ff6 100644
--- a/arch/parisc/kernel/smp.c
+++ b/arch/parisc/kernel/smp.c
@@ -279,7 +279,7 @@ smp_cpu_init(int cpunum)
set_cpu_online(cpunum, true);

/* Initialise the idle task for this CPU */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;
BUG_ON(current->mm);
enter_lazy_tlb(&init_mm, current);
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 9c6f3fd58059..42b82364c782 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -707,7 +707,7 @@ void start_secondary(void *unused)
unsigned int cpu = smp_processor_id();
int i, base;

- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;

smp_store_cpu_info(cpu);
diff --git a/arch/s390/kernel/processor.c b/arch/s390/kernel/processor.c
index 9e60ef144d03..b8fc689c9e2a 100644
--- a/arch/s390/kernel/processor.c
+++ b/arch/s390/kernel/processor.c
@@ -73,7 +73,7 @@ void cpu_init(void)
get_cpu_id(id);
if (machine_has_cpu_mhz)
update_cpu_mhz(NULL);
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;
BUG_ON(current->mm);
enter_lazy_tlb(&init_mm, current);
diff --git a/arch/score/kernel/traps.c b/arch/score/kernel/traps.c
index 5cea1e750cec..6f6e5a39d147 100644
--- a/arch/score/kernel/traps.c
+++ b/arch/score/kernel/traps.c
@@ -336,7 +336,7 @@ void __init trap_init(void)
set_except_vector(18, handle_dbe);
flush_icache_range(DEBUG_VECTOR_BASE_ADDR, IRQ_VECTOR_BASE_ADDR);

- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;
cpu_cache_init();
}
diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
index 38e7860845db..ee379c699c08 100644
--- a/arch/sh/kernel/smp.c
+++ b/arch/sh/kernel/smp.c
@@ -178,7 +178,7 @@ asmlinkage void start_secondary(void)
struct mm_struct *mm = &init_mm;

enable_mmu();
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
atomic_inc(&mm->mm_users);
current->active_mm = mm;
#ifdef CONFIG_MMU
diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
index 71e16f2241c2..b99d33797e1d 100644
--- a/arch/sparc/kernel/leon_smp.c
+++ b/arch/sparc/kernel/leon_smp.c
@@ -93,7 +93,7 @@ void leon_cpu_pre_online(void *arg)
: "memory" /* paranoid */);

/* Attach to the address space of init_task. */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;

while (!cpumask_test_cpu(cpuid, &smp_commenced_mask))
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 8182f7caf5b1..c1d2bed22961 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -122,7 +122,7 @@ void smp_callin(void)
current_thread_info()->new_child = 0;

/* Attach to the address space of init_task. */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;

/* inform the notifiers about the new cpu */
diff --git a/arch/sparc/kernel/sun4d_smp.c b/arch/sparc/kernel/sun4d_smp.c
index 9d98e5002a09..7b55c50eabe5 100644
--- a/arch/sparc/kernel/sun4d_smp.c
+++ b/arch/sparc/kernel/sun4d_smp.c
@@ -93,7 +93,7 @@ void sun4d_cpu_pre_online(void *arg)
show_leds(cpuid);

/* Attach to the address space of init_task. */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;

local_ops->cache_all();
diff --git a/arch/sparc/kernel/sun4m_smp.c b/arch/sparc/kernel/sun4m_smp.c
index 278c40abce82..633c4cf6fdb0 100644
--- a/arch/sparc/kernel/sun4m_smp.c
+++ b/arch/sparc/kernel/sun4m_smp.c
@@ -59,7 +59,7 @@ void sun4m_cpu_pre_online(void *arg)
: "memory" /* paranoid */);

/* Attach to the address space of init_task. */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;

while (!cpumask_test_cpu(cpuid, &smp_commenced_mask))
diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
index 4f21df7d4f13..ecddac5a4c96 100644
--- a/arch/sparc/kernel/traps_32.c
+++ b/arch/sparc/kernel/traps_32.c
@@ -448,7 +448,7 @@ void trap_init(void)
thread_info_offsets_are_bolixed_pete();

/* Attach to the address space of init_task. */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;

/* NOTE: Other cpus have this done as they are started
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index 496fa926e1e0..83dd1331a30e 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -2764,6 +2764,6 @@ void __init trap_init(void)
/* Attach to the address space of init_task. On SMP we
* do this in smp.c:smp_callin for other cpus.
*/
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;
}
diff --git a/arch/tile/kernel/smpboot.c b/arch/tile/kernel/smpboot.c
index 6c0abaacec33..53ce940a5016 100644
--- a/arch/tile/kernel/smpboot.c
+++ b/arch/tile/kernel/smpboot.c
@@ -160,7 +160,7 @@ static void start_secondary(void)
__this_cpu_write(current_asid, min_asid);

/* Set up this thread as another owner of the init_mm */
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
current->active_mm = &init_mm;
if (current->mm)
BUG();
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 729f92ba8224..5b88f78c40f5 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1498,7 +1498,7 @@ void cpu_init(void)
for (i = 0; i <= IO_BITMAP_LONGS; i++)
t->io_bitmap[i] = ~0UL;

- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
me->active_mm = &init_mm;
BUG_ON(me->mm);
enter_lazy_tlb(&init_mm, me);
@@ -1549,7 +1549,7 @@ void cpu_init(void)
/*
* Set up and load the per-CPU TSS and LDT
*/
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
curr->active_mm = &init_mm;
BUG_ON(curr->mm);
enter_lazy_tlb(&init_mm, curr);
diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c
index fc4ad21a5ed4..9bf5cea3bae4 100644
--- a/arch/xtensa/kernel/smp.c
+++ b/arch/xtensa/kernel/smp.c
@@ -136,7 +136,7 @@ void secondary_start_kernel(void)
/* All kernel threads share the same mm context. */

atomic_inc(&mm->mm_users);
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));
enter_lazy_tlb(mm, current);
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index ef7c8de7060e..ca5f2aa7232d 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -262,7 +262,7 @@ static void kfd_process_notifier_release(struct mmu_notifier *mn,
* and because the mmu_notifier_unregister function also drop
* mm_count we need to take an extra count here.
*/
- atomic_inc(&p->mm->mm_count);
+ mmgrab(p->mm);
mmu_notifier_unregister_no_release(&p->mmu_notifier, p->mm);
mmu_notifier_call_srcu(&p->rcu, &kfd_process_destroy_delayed);
}
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index d068af2ec3a3..1f27529cb48e 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -334,7 +334,7 @@ i915_gem_userptr_init__mm_struct(struct drm_i915_gem_object *obj)
mm->i915 = to_i915(obj->base.dev);

mm->mm = current->mm;
- atomic_inc(&current->mm->mm_count);
+ mmgrab(current->mm);

mm->mn = NULL;

diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c
index bd786b7bd30b..2e1a6643a910 100644
--- a/drivers/infiniband/hw/hfi1/file_ops.c
+++ b/drivers/infiniband/hw/hfi1/file_ops.c
@@ -185,7 +185,7 @@ static int hfi1_file_open(struct inode *inode, struct file *fp)
if (fd) {
fd->rec_cpu_num = -1; /* no cpu affinity by default */
fd->mm = current->mm;
- atomic_inc(&fd->mm->mm_count);
+ mmgrab(fd->mm);
fp->private_data = fd;
} else {
fp->private_data = NULL;
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 5ea836362870..32f04999d930 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -798,7 +798,7 @@ struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode)

if (!IS_ERR_OR_NULL(mm)) {
/* ensure this mm_struct can't be freed */
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
/* but do not pin its memory */
mmput(mm);
}
@@ -1096,7 +1096,7 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
if (p) {
if (atomic_read(&p->mm->mm_users) > 1) {
mm = p->mm;
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
}
task_unlock(p);
}
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index d96e2f30084b..a02bbf5897e6 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1306,7 +1306,7 @@ static struct file *userfaultfd_file_create(int flags)
ctx->released = false;
ctx->mm = current->mm;
/* prevent the mm struct to be freed */
- atomic_inc(&ctx->mm->mm_count);
+ mmgrab(ctx->mm);

file = anon_inode_getfile("[userfaultfd]", &userfaultfd_fops, ctx,
O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS));
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a440cf178191..6ce46220bda2 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2911,6 +2911,28 @@ static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
*/
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)
diff --git a/kernel/exit.c b/kernel/exit.c
index aacff8e2aec0..a0bfdace6a07 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -509,7 +509,7 @@ static void exit_mm(struct task_struct *tsk)
__set_task_state(tsk, TASK_RUNNING);
down_read(&mm->mmap_sem);
}
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
BUG_ON(mm != tsk->active_mm);
/* more a memory barrier than a real lock */
task_lock(tsk);
diff --git a/kernel/futex.c b/kernel/futex.c
index 9246d9f593d1..cc84e6bd6a4d 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -338,7 +338,7 @@ static inline bool should_fail_futex(bool fshared)

static inline void futex_get_mm(union futex_key *key)
{
- atomic_inc(&key->private.mm->mm_count);
+ mmgrab(key->private.mm);
/*
* Ensure futex_get_mm() implies a full barrier such that
* get_futex_key() implies a full barrier. This is relied upon
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 966556ebdbb3..49d7076d93c3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2878,7 +2878,7 @@ context_switch(struct rq *rq, struct task_struct *prev,

if (!mm) {
next->active_mm = oldmm;
- atomic_inc(&oldmm->mm_count);
+ mmgrab(oldmm);
enter_lazy_tlb(oldmm, next);
} else
switch_mm_irqs_off(oldmm, mm, next);
@@ -7686,7 +7686,7 @@ void __init sched_init(void)
/*
* The boot idle thread does lazy MMU switching as well:
*/
- atomic_inc(&init_mm.mm_count);
+ mmgrab(&init_mm);
enter_lazy_tlb(&init_mm, current);

/*
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index e32389a97030..4cf3b3af6313 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -420,7 +420,7 @@ int __khugepaged_enter(struct mm_struct *mm)
list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
spin_unlock(&khugepaged_mm_lock);

- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
if (wakeup)
wake_up_interruptible(&khugepaged_wait);

diff --git a/mm/ksm.c b/mm/ksm.c
index 9ae6011a41f8..5a49aad9d87b 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1813,7 +1813,7 @@ int __ksm_enter(struct mm_struct *mm)
spin_unlock(&ksm_mmlist_lock);

set_bit(MMF_VM_MERGEABLE, &mm->flags);
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);

if (needs_wakeup)
wake_up_interruptible(&ksm_thread_wait);
diff --git a/mm/mmu_context.c b/mm/mmu_context.c
index 6f4d27c5bb32..daf67bb02b4a 100644
--- a/mm/mmu_context.c
+++ b/mm/mmu_context.c
@@ -25,7 +25,7 @@ void use_mm(struct mm_struct *mm)
task_lock(tsk);
active_mm = tsk->active_mm;
if (active_mm != mm) {
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
tsk->active_mm = mm;
}
tsk->mm = mm;
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index f4259e496f83..32bc9f2ff7eb 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -275,7 +275,7 @@ static int do_mmu_notifier_register(struct mmu_notifier *mn,
mm->mmu_notifier_mm = mmu_notifier_mm;
mmu_notifier_mm = NULL;
}
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);

/*
* Serialize the update against mmu_notifier_unregister. A
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index ec9f11d4f094..ead093c6f2a6 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -660,7 +660,7 @@ static void mark_oom_victim(struct task_struct *tsk)

/* oom_mm is bound to the signal struct life time. */
if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm))
- atomic_inc(&tsk->signal->oom_mm->mm_count);
+ mmgrab(tsk->signal->oom_mm);

/*
* Make sure that the task is woken up from uninterruptible sleep
@@ -877,7 +877,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message)

/* Get a reference to safely compare mm after task_unlock(victim) */
mm = victim->mm;
- atomic_inc(&mm->mm_count);
+ mmgrab(mm);
/*
* We should send SIGKILL before setting TIF_MEMDIE in order to prevent
* the OOM victim from depleting the memory reserves from the user
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index de102cae7125..3a61b572fa2c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -616,7 +616,7 @@ static struct kvm *kvm_create_vm(unsigned long type)
return ERR_PTR(-ENOMEM);

spin_lock_init(&kvm->mmu_lock);
- atomic_inc(&current->mm->mm_count);
+ mmgrab(current->mm);
kvm->mm = current->mm;
kvm_eventfd_init(kvm);
mutex_init(&kvm->lock);
--
2.11.0.1.gaa10c3f