Commit f1f10076 authored by Vegard Nossum's avatar Vegard Nossum Committed by Linus Torvalds

mm: add new mmgrab() helper

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.)

Link: http://lkml.kernel.org/r/20161218123229.22952-1-vegard.nossum@oracle.comSigned-off-by: default avatarVegard Nossum <vegard.nossum@oracle.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 522b837c
......@@ -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 */
......
......@@ -140,7 +140,7 @@ 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));
......
......@@ -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));
......
......@@ -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;
/*
......
......@@ -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();
......
......@@ -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();
......
......@@ -994,7 +994,7 @@ 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);
......
......@@ -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();
......
......@@ -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);
......
......@@ -2232,7 +2232,7 @@ 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);
......
......@@ -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);
......
......@@ -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);
......
......@@ -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);
......
......@@ -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);
......
......@@ -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();
}
......@@ -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
......
......@@ -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))
......
......@@ -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 */
......
......@@ -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();
......
......@@ -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))
......
......@@ -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
......
......@@ -2837,6 +2837,6 @@ 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;
}
......@@ -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();
......
......@@ -1510,7 +1510,7 @@ 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);
......@@ -1561,7 +1561,7 @@ 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);
......
......@@ -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);
......
......@@ -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);
}
......
......@@ -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;
......
......@@ -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;
......
......@@ -766,7 +766,7 @@ 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);
}
......@@ -1064,7 +1064,7 @@ 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);
}
......
......@@ -1847,7 +1847,7 @@ 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));
......
......@@ -2904,6 +2904,28 @@ 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)
......
......@@ -539,7 +539,7 @@ static void exit_mm(void)
__set_current_state(TASK_RUNNING);
down_read(&mm->mmap_sem);
}
atomic_inc(&mm->mm_count);
mmgrab(mm);
BUG_ON(mm != current->active_mm);
/* more a memory barrier than a real lock */
task_lock(current);
......
......@@ -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
......
......@@ -2847,7 +2847,7 @@ 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);
......@@ -6098,7 +6098,7 @@ 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);
/*
......
......@@ -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);
......
......@@ -1854,7 +1854,7 @@ 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);
......
......@@ -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;
......
......@@ -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
......
......@@ -653,7 +653,7 @@ 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
......@@ -870,7 +870,7 @@ 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
......
......@@ -611,7 +611,7 @@ 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);
......
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