summaryrefslogtreecommitdiff
path: root/include/linux/sched/mm.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/linux/sched/mm.h')
-rw-r--r--include/linux/sched/mm.h174
1 files changed, 174 insertions, 0 deletions
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
new file mode 100644
index 000000000000..830953ebb391
--- /dev/null
+++ b/include/linux/sched/mm.h
@@ -0,0 +1,174 @@
+#ifndef _LINUX_SCHED_MM_H
+#define _LINUX_SCHED_MM_H
+
+#include <linux/kernel.h>
+#include <linux/atomic.h>
+#include <linux/sched.h>
+#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 *);
+
+#ifdef CONFIG_MEMCG
+extern void mm_update_next_owner(struct mm_struct *mm);
+#else
+static inline void mm_update_next_owner(struct mm_struct *mm)
+{
+}
+#endif /* CONFIG_MEMCG */
+
+#ifdef CONFIG_MMU
+extern void arch_pick_mmap_layout(struct mm_struct *mm);
+extern unsigned long
+arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
+ unsigned long, unsigned long);
+extern unsigned long
+arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags);
+#else
+static inline void arch_pick_mmap_layout(struct mm_struct *mm) {}
+#endif
+
+static inline bool in_vfork(struct task_struct *tsk)
+{
+ bool ret;
+
+ /*
+ * need RCU to access ->real_parent if CLONE_VM was used along with
+ * CLONE_PARENT.
+ *
+ * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
+ * imply CLONE_VM
+ *
+ * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus
+ * ->real_parent is not necessarily the task doing vfork(), so in
+ * theory we can't rely on task_lock() if we want to dereference it.
+ *
+ * And in this case we can't trust the real_parent->mm == tsk->mm
+ * check, it can be false negative. But we do not care, if init or
+ * another oom-unkillable task does this it should blame itself.
+ */
+ rcu_read_lock();
+ ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm;
+ rcu_read_unlock();
+
+ return ret;
+}
+
+/* __GFP_IO isn't allowed if PF_MEMALLOC_NOIO is set in current->flags
+ * __GFP_FS is also cleared as it implies __GFP_IO.
+ */
+static inline gfp_t memalloc_noio_flags(gfp_t flags)
+{
+ if (unlikely(current->flags & PF_MEMALLOC_NOIO))
+ flags &= ~(__GFP_IO | __GFP_FS);
+ return flags;
+}
+
+static inline unsigned int memalloc_noio_save(void)
+{
+ unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
+ current->flags |= PF_MEMALLOC_NOIO;
+ return flags;
+}
+
+static inline void memalloc_noio_restore(unsigned int flags)
+{
+ current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
+}
+
+#endif /* _LINUX_SCHED_MM_H */