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.com
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 77ae323..34bce5c 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 cf211c0..520e4c3 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -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);
diff --git a/mm/mmu_context.c b/mm/mmu_context.c
index 6f4d27c..daf67bb 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 f4259e4..32bc9f2 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 578321f..51c0918 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -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
