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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
6e84f315 IM |
2 | #ifndef _LINUX_SCHED_MM_H |
3 | #define _LINUX_SCHED_MM_H | |
4 | ||
b8d6d80b IM |
5 | #include <linux/kernel.h> |
6 | #include <linux/atomic.h> | |
6e84f315 | 7 | #include <linux/sched.h> |
589ee628 | 8 | #include <linux/mm_types.h> |
fd771233 | 9 | #include <linux/gfp.h> |
6e84f315 | 10 | |
68e21be2 IM |
11 | /* |
12 | * Routines for handling mm_structs | |
13 | */ | |
14 | extern struct mm_struct * mm_alloc(void); | |
15 | ||
16 | /** | |
17 | * mmgrab() - Pin a &struct mm_struct. | |
18 | * @mm: The &struct mm_struct to pin. | |
19 | * | |
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 | |
23 | * accessing it. | |
24 | * | |
25 | * This is a preferred way to to pin @mm for a longer/unbounded amount | |
26 | * of time. | |
27 | * | |
28 | * Use mmdrop() to release the reference acquired by mmgrab(). | |
29 | * | |
30 | * See also <Documentation/vm/active_mm.txt> for an in-depth explanation | |
31 | * of &mm_struct.mm_count vs &mm_struct.mm_users. | |
32 | */ | |
33 | static inline void mmgrab(struct mm_struct *mm) | |
34 | { | |
35 | atomic_inc(&mm->mm_count); | |
36 | } | |
37 | ||
38 | /* mmdrop drops the mm and the page tables */ | |
39 | extern void __mmdrop(struct mm_struct *); | |
40 | static inline void mmdrop(struct mm_struct *mm) | |
41 | { | |
42 | if (unlikely(atomic_dec_and_test(&mm->mm_count))) | |
43 | __mmdrop(mm); | |
44 | } | |
45 | ||
46 | static inline void mmdrop_async_fn(struct work_struct *work) | |
47 | { | |
48 | struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work); | |
49 | __mmdrop(mm); | |
50 | } | |
51 | ||
52 | static inline void mmdrop_async(struct mm_struct *mm) | |
53 | { | |
54 | if (unlikely(atomic_dec_and_test(&mm->mm_count))) { | |
55 | INIT_WORK(&mm->async_put_work, mmdrop_async_fn); | |
56 | schedule_work(&mm->async_put_work); | |
57 | } | |
58 | } | |
59 | ||
60 | /** | |
61 | * mmget() - Pin the address space associated with a &struct mm_struct. | |
62 | * @mm: The address space to pin. | |
63 | * | |
64 | * Make sure that the address space of the given &struct mm_struct doesn't | |
65 | * go away. This does not protect against parts of the address space being | |
66 | * modified or freed, however. | |
67 | * | |
68 | * Never use this function to pin this address space for an | |
69 | * unbounded/indefinite amount of time. | |
70 | * | |
71 | * Use mmput() to release the reference acquired by mmget(). | |
72 | * | |
73 | * See also <Documentation/vm/active_mm.txt> for an in-depth explanation | |
74 | * of &mm_struct.mm_count vs &mm_struct.mm_users. | |
75 | */ | |
76 | static inline void mmget(struct mm_struct *mm) | |
77 | { | |
78 | atomic_inc(&mm->mm_users); | |
79 | } | |
80 | ||
81 | static inline bool mmget_not_zero(struct mm_struct *mm) | |
82 | { | |
83 | return atomic_inc_not_zero(&mm->mm_users); | |
84 | } | |
85 | ||
86 | /* mmput gets rid of the mappings and all user-space */ | |
87 | extern void mmput(struct mm_struct *); | |
a1b2289c SY |
88 | #ifdef CONFIG_MMU |
89 | /* same as above but performs the slow path from the async context. Can | |
90 | * be called from the atomic context as well | |
91 | */ | |
92 | void mmput_async(struct mm_struct *); | |
93 | #endif | |
68e21be2 IM |
94 | |
95 | /* Grab a reference to a task's mm, if it is not already going away */ | |
96 | extern struct mm_struct *get_task_mm(struct task_struct *task); | |
97 | /* | |
98 | * Grab a reference to a task's mm, if it is not already going away | |
99 | * and ptrace_may_access with the mode parameter passed to it | |
100 | * succeeds. | |
101 | */ | |
102 | extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode); | |
103 | /* Remove the current tasks stale references to the old mm_struct */ | |
104 | extern void mm_release(struct task_struct *, struct mm_struct *); | |
105 | ||
4240c8bf IM |
106 | #ifdef CONFIG_MEMCG |
107 | extern void mm_update_next_owner(struct mm_struct *mm); | |
108 | #else | |
109 | static inline void mm_update_next_owner(struct mm_struct *mm) | |
110 | { | |
111 | } | |
112 | #endif /* CONFIG_MEMCG */ | |
113 | ||
114 | #ifdef CONFIG_MMU | |
115 | extern void arch_pick_mmap_layout(struct mm_struct *mm); | |
116 | extern unsigned long | |
117 | arch_get_unmapped_area(struct file *, unsigned long, unsigned long, | |
118 | unsigned long, unsigned long); | |
119 | extern unsigned long | |
120 | arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr, | |
121 | unsigned long len, unsigned long pgoff, | |
122 | unsigned long flags); | |
123 | #else | |
124 | static inline void arch_pick_mmap_layout(struct mm_struct *mm) {} | |
125 | #endif | |
126 | ||
d026ce79 IM |
127 | static inline bool in_vfork(struct task_struct *tsk) |
128 | { | |
129 | bool ret; | |
130 | ||
131 | /* | |
132 | * need RCU to access ->real_parent if CLONE_VM was used along with | |
133 | * CLONE_PARENT. | |
134 | * | |
135 | * We check real_parent->mm == tsk->mm because CLONE_VFORK does not | |
136 | * imply CLONE_VM | |
137 | * | |
138 | * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus | |
139 | * ->real_parent is not necessarily the task doing vfork(), so in | |
140 | * theory we can't rely on task_lock() if we want to dereference it. | |
141 | * | |
142 | * And in this case we can't trust the real_parent->mm == tsk->mm | |
143 | * check, it can be false negative. But we do not care, if init or | |
144 | * another oom-unkillable task does this it should blame itself. | |
145 | */ | |
146 | rcu_read_lock(); | |
147 | ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm; | |
148 | rcu_read_unlock(); | |
149 | ||
150 | return ret; | |
151 | } | |
152 | ||
7dea19f9 MH |
153 | /* |
154 | * Applies per-task gfp context to the given allocation flags. | |
155 | * PF_MEMALLOC_NOIO implies GFP_NOIO | |
156 | * PF_MEMALLOC_NOFS implies GFP_NOFS | |
74444eda | 157 | */ |
7dea19f9 | 158 | static inline gfp_t current_gfp_context(gfp_t flags) |
74444eda | 159 | { |
7dea19f9 MH |
160 | /* |
161 | * NOIO implies both NOIO and NOFS and it is a weaker context | |
162 | * so always make sure it makes precendence | |
163 | */ | |
74444eda IM |
164 | if (unlikely(current->flags & PF_MEMALLOC_NOIO)) |
165 | flags &= ~(__GFP_IO | __GFP_FS); | |
7dea19f9 MH |
166 | else if (unlikely(current->flags & PF_MEMALLOC_NOFS)) |
167 | flags &= ~__GFP_FS; | |
74444eda IM |
168 | return flags; |
169 | } | |
170 | ||
d92a8cfc PZ |
171 | #ifdef CONFIG_LOCKDEP |
172 | extern void fs_reclaim_acquire(gfp_t gfp_mask); | |
173 | extern void fs_reclaim_release(gfp_t gfp_mask); | |
174 | #else | |
175 | static inline void fs_reclaim_acquire(gfp_t gfp_mask) { } | |
176 | static inline void fs_reclaim_release(gfp_t gfp_mask) { } | |
177 | #endif | |
178 | ||
74444eda IM |
179 | static inline unsigned int memalloc_noio_save(void) |
180 | { | |
181 | unsigned int flags = current->flags & PF_MEMALLOC_NOIO; | |
182 | current->flags |= PF_MEMALLOC_NOIO; | |
183 | return flags; | |
184 | } | |
185 | ||
186 | static inline void memalloc_noio_restore(unsigned int flags) | |
187 | { | |
188 | current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags; | |
189 | } | |
190 | ||
7dea19f9 MH |
191 | static inline unsigned int memalloc_nofs_save(void) |
192 | { | |
193 | unsigned int flags = current->flags & PF_MEMALLOC_NOFS; | |
194 | current->flags |= PF_MEMALLOC_NOFS; | |
195 | return flags; | |
196 | } | |
197 | ||
198 | static inline void memalloc_nofs_restore(unsigned int flags) | |
199 | { | |
200 | current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags; | |
201 | } | |
202 | ||
499118e9 VB |
203 | static inline unsigned int memalloc_noreclaim_save(void) |
204 | { | |
205 | unsigned int flags = current->flags & PF_MEMALLOC; | |
206 | current->flags |= PF_MEMALLOC; | |
207 | return flags; | |
208 | } | |
209 | ||
210 | static inline void memalloc_noreclaim_restore(unsigned int flags) | |
211 | { | |
212 | current->flags = (current->flags & ~PF_MEMALLOC) | flags; | |
213 | } | |
214 | ||
a961e409 MD |
215 | #ifdef CONFIG_MEMBARRIER |
216 | enum { | |
217 | MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0), | |
218 | MEMBARRIER_STATE_SWITCH_MM = (1U << 1), | |
219 | }; | |
220 | ||
221 | static inline void membarrier_execve(struct task_struct *t) | |
222 | { | |
223 | atomic_set(&t->mm->membarrier_state, 0); | |
224 | } | |
225 | #else | |
226 | static inline void membarrier_execve(struct task_struct *t) | |
227 | { | |
228 | } | |
229 | #endif | |
230 | ||
6e84f315 | 231 | #endif /* _LINUX_SCHED_MM_H */ |