1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SCHED_MM_H
3 #define _LINUX_SCHED_MM_H
5 #include <linux/kernel.h>
6 #include <linux/atomic.h>
7 #include <linux/sched.h>
8 #include <linux/mm_types.h>
12 * Routines for handling mm_structs
14 extern struct mm_struct *mm_alloc(void);
17 * mmgrab() - Pin a &struct mm_struct.
18 * @mm: The &struct mm_struct to pin.
20 * Make sure that @mm will not get freed even after the owning task
21 * exits. This doesn't guarantee that the associated address space
22 * will still exist later on and mmget_not_zero() has to be used before
25 * This is a preferred way to to pin @mm for a longer/unbounded amount
28 * Use mmdrop() to release the reference acquired by mmgrab().
30 * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
31 * of &mm_struct.mm_count vs &mm_struct.mm_users.
33 static inline void mmgrab(struct mm_struct *mm)
35 atomic_inc(&mm->mm_count);
38 extern void mmdrop(struct mm_struct *mm);
41 * mmget() - Pin the address space associated with a &struct mm_struct.
42 * @mm: The address space to pin.
44 * Make sure that the address space of the given &struct mm_struct doesn't
45 * go away. This does not protect against parts of the address space being
46 * modified or freed, however.
48 * Never use this function to pin this address space for an
49 * unbounded/indefinite amount of time.
51 * Use mmput() to release the reference acquired by mmget().
53 * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
54 * of &mm_struct.mm_count vs &mm_struct.mm_users.
56 static inline void mmget(struct mm_struct *mm)
58 atomic_inc(&mm->mm_users);
61 static inline bool mmget_not_zero(struct mm_struct *mm)
63 return atomic_inc_not_zero(&mm->mm_users);
66 /* mmput gets rid of the mappings and all user-space */
67 extern void mmput(struct mm_struct *);
69 /* same as above but performs the slow path from the async context. Can
70 * be called from the atomic context as well
72 void mmput_async(struct mm_struct *);
75 /* Grab a reference to a task's mm, if it is not already going away */
76 extern struct mm_struct *get_task_mm(struct task_struct *task);
78 * Grab a reference to a task's mm, if it is not already going away
79 * and ptrace_may_access with the mode parameter passed to it
82 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
83 /* Remove the current tasks stale references to the old mm_struct */
84 extern void mm_release(struct task_struct *, struct mm_struct *);
87 extern void mm_update_next_owner(struct mm_struct *mm);
89 static inline void mm_update_next_owner(struct mm_struct *mm)
92 #endif /* CONFIG_MEMCG */
95 extern void arch_pick_mmap_layout(struct mm_struct *mm);
97 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
98 unsigned long, unsigned long);
100 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
101 unsigned long len, unsigned long pgoff,
102 unsigned long flags);
104 static inline void arch_pick_mmap_layout(struct mm_struct *mm) {}
107 static inline bool in_vfork(struct task_struct *tsk)
112 * need RCU to access ->real_parent if CLONE_VM was used along with
115 * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
118 * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus
119 * ->real_parent is not necessarily the task doing vfork(), so in
120 * theory we can't rely on task_lock() if we want to dereference it.
122 * And in this case we can't trust the real_parent->mm == tsk->mm
123 * check, it can be false negative. But we do not care, if init or
124 * another oom-unkillable task does this it should blame itself.
127 ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm;
134 * Applies per-task gfp context to the given allocation flags.
135 * PF_MEMALLOC_NOIO implies GFP_NOIO
136 * PF_MEMALLOC_NOFS implies GFP_NOFS
138 static inline gfp_t current_gfp_context(gfp_t flags)
141 * NOIO implies both NOIO and NOFS and it is a weaker context
142 * so always make sure it makes precendence
144 if (unlikely(current->flags & PF_MEMALLOC_NOIO))
145 flags &= ~(__GFP_IO | __GFP_FS);
146 else if (unlikely(current->flags & PF_MEMALLOC_NOFS))
151 #ifdef CONFIG_LOCKDEP
152 extern void fs_reclaim_acquire(gfp_t gfp_mask);
153 extern void fs_reclaim_release(gfp_t gfp_mask);
155 static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
156 static inline void fs_reclaim_release(gfp_t gfp_mask) { }
159 static inline unsigned int memalloc_noio_save(void)
161 unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
162 current->flags |= PF_MEMALLOC_NOIO;
166 static inline void memalloc_noio_restore(unsigned int flags)
168 current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
171 static inline unsigned int memalloc_nofs_save(void)
173 unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
174 current->flags |= PF_MEMALLOC_NOFS;
178 static inline void memalloc_nofs_restore(unsigned int flags)
180 current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
183 static inline unsigned int memalloc_noreclaim_save(void)
185 unsigned int flags = current->flags & PF_MEMALLOC;
186 current->flags |= PF_MEMALLOC;
190 static inline void memalloc_noreclaim_restore(unsigned int flags)
192 current->flags = (current->flags & ~PF_MEMALLOC) | flags;
195 #ifdef CONFIG_MEMBARRIER
197 MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
198 MEMBARRIER_STATE_SWITCH_MM = (1U << 1),
201 static inline void membarrier_execve(struct task_struct *t)
203 atomic_set(&t->mm->membarrier_state, 0);
206 static inline void membarrier_execve(struct task_struct *t)
211 #endif /* _LINUX_SCHED_MM_H */