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>
10 #include <linux/sync_core.h>
13 * Routines for handling mm_structs
15 extern struct mm_struct *mm_alloc(void);
18 * mmgrab() - Pin a &struct mm_struct.
19 * @mm: The &struct mm_struct to pin.
21 * Make sure that @mm will not get freed even after the owning task
22 * exits. This doesn't guarantee that the associated address space
23 * will still exist later on and mmget_not_zero() has to be used before
26 * This is a preferred way to to pin @mm for a longer/unbounded amount
29 * Use mmdrop() to release the reference acquired by mmgrab().
31 * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
32 * of &mm_struct.mm_count vs &mm_struct.mm_users.
34 static inline void mmgrab(struct mm_struct *mm)
36 atomic_inc(&mm->mm_count);
39 extern void __mmdrop(struct mm_struct *mm);
41 static inline void mmdrop(struct mm_struct *mm)
44 * The implicit full barrier implied by atomic_dec_and_test() is
45 * required by the membarrier system call before returning to
46 * user-space, after storing to rq->curr.
48 if (unlikely(atomic_dec_and_test(&mm->mm_count)))
53 * mmget() - Pin the address space associated with a &struct mm_struct.
54 * @mm: The address space to pin.
56 * Make sure that the address space of the given &struct mm_struct doesn't
57 * go away. This does not protect against parts of the address space being
58 * modified or freed, however.
60 * Never use this function to pin this address space for an
61 * unbounded/indefinite amount of time.
63 * Use mmput() to release the reference acquired by mmget().
65 * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
66 * of &mm_struct.mm_count vs &mm_struct.mm_users.
68 static inline void mmget(struct mm_struct *mm)
70 atomic_inc(&mm->mm_users);
73 static inline bool mmget_not_zero(struct mm_struct *mm)
75 return atomic_inc_not_zero(&mm->mm_users);
78 /* mmput gets rid of the mappings and all user-space */
79 extern void mmput(struct mm_struct *);
81 /* same as above but performs the slow path from the async context. Can
82 * be called from the atomic context as well
84 void mmput_async(struct mm_struct *);
87 /* Grab a reference to a task's mm, if it is not already going away */
88 extern struct mm_struct *get_task_mm(struct task_struct *task);
90 * Grab a reference to a task's mm, if it is not already going away
91 * and ptrace_may_access with the mode parameter passed to it
94 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
95 /* Remove the current tasks stale references to the old mm_struct */
96 extern void mm_release(struct task_struct *, struct mm_struct *);
99 extern void mm_update_next_owner(struct mm_struct *mm);
101 static inline void mm_update_next_owner(struct mm_struct *mm)
104 #endif /* CONFIG_MEMCG */
107 extern void arch_pick_mmap_layout(struct mm_struct *mm,
108 struct rlimit *rlim_stack);
110 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
111 unsigned long, unsigned long);
113 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
114 unsigned long len, unsigned long pgoff,
115 unsigned long flags);
117 static inline void arch_pick_mmap_layout(struct mm_struct *mm,
118 struct rlimit *rlim_stack) {}
121 static inline bool in_vfork(struct task_struct *tsk)
126 * need RCU to access ->real_parent if CLONE_VM was used along with
129 * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
132 * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus
133 * ->real_parent is not necessarily the task doing vfork(), so in
134 * theory we can't rely on task_lock() if we want to dereference it.
136 * And in this case we can't trust the real_parent->mm == tsk->mm
137 * check, it can be false negative. But we do not care, if init or
138 * another oom-unkillable task does this it should blame itself.
141 ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm;
148 * Applies per-task gfp context to the given allocation flags.
149 * PF_MEMALLOC_NOIO implies GFP_NOIO
150 * PF_MEMALLOC_NOFS implies GFP_NOFS
152 static inline gfp_t current_gfp_context(gfp_t flags)
155 * NOIO implies both NOIO and NOFS and it is a weaker context
156 * so always make sure it makes precendence
158 if (unlikely(current->flags & PF_MEMALLOC_NOIO))
159 flags &= ~(__GFP_IO | __GFP_FS);
160 else if (unlikely(current->flags & PF_MEMALLOC_NOFS))
165 #ifdef CONFIG_LOCKDEP
166 extern void fs_reclaim_acquire(gfp_t gfp_mask);
167 extern void fs_reclaim_release(gfp_t gfp_mask);
169 static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
170 static inline void fs_reclaim_release(gfp_t gfp_mask) { }
173 static inline unsigned int memalloc_noio_save(void)
175 unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
176 current->flags |= PF_MEMALLOC_NOIO;
180 static inline void memalloc_noio_restore(unsigned int flags)
182 current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
185 static inline unsigned int memalloc_nofs_save(void)
187 unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
188 current->flags |= PF_MEMALLOC_NOFS;
192 static inline void memalloc_nofs_restore(unsigned int flags)
194 current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
197 static inline unsigned int memalloc_noreclaim_save(void)
199 unsigned int flags = current->flags & PF_MEMALLOC;
200 current->flags |= PF_MEMALLOC;
204 static inline void memalloc_noreclaim_restore(unsigned int flags)
206 current->flags = (current->flags & ~PF_MEMALLOC) | flags;
209 #ifdef CONFIG_MEMBARRIER
211 MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
212 MEMBARRIER_STATE_PRIVATE_EXPEDITED = (1U << 1),
213 MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY = (1U << 2),
214 MEMBARRIER_STATE_GLOBAL_EXPEDITED = (1U << 3),
215 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY = (1U << 4),
216 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE = (1U << 5),
220 MEMBARRIER_FLAG_SYNC_CORE = (1U << 0),
223 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
224 #include <asm/membarrier.h>
227 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
229 if (likely(!(atomic_read(&mm->membarrier_state) &
230 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE)))
232 sync_core_before_usermode();
235 static inline void membarrier_execve(struct task_struct *t)
237 atomic_set(&t->mm->membarrier_state, 0);
240 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
241 static inline void membarrier_arch_switch_mm(struct mm_struct *prev,
242 struct mm_struct *next,
243 struct task_struct *tsk)
247 static inline void membarrier_execve(struct task_struct *t)
250 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
255 #endif /* _LINUX_SCHED_MM_H */