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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> |
70216e18 | 10 | #include <linux/sync_core.h> |
6e84f315 | 11 | |
68e21be2 IM |
12 | /* |
13 | * Routines for handling mm_structs | |
14 | */ | |
d70f2a14 | 15 | extern struct mm_struct *mm_alloc(void); |
68e21be2 IM |
16 | |
17 | /** | |
18 | * mmgrab() - Pin a &struct mm_struct. | |
19 | * @mm: The &struct mm_struct to pin. | |
20 | * | |
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 | |
24 | * accessing it. | |
25 | * | |
26 | * This is a preferred way to to pin @mm for a longer/unbounded amount | |
27 | * of time. | |
28 | * | |
29 | * Use mmdrop() to release the reference acquired by mmgrab(). | |
30 | * | |
31 | * See also <Documentation/vm/active_mm.txt> for an in-depth explanation | |
32 | * of &mm_struct.mm_count vs &mm_struct.mm_users. | |
33 | */ | |
34 | static inline void mmgrab(struct mm_struct *mm) | |
35 | { | |
36 | atomic_inc(&mm->mm_count); | |
37 | } | |
38 | ||
d34bc48f AM |
39 | extern void __mmdrop(struct mm_struct *mm); |
40 | ||
41 | static inline void mmdrop(struct mm_struct *mm) | |
42 | { | |
43 | /* | |
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. | |
47 | */ | |
48 | if (unlikely(atomic_dec_and_test(&mm->mm_count))) | |
49 | __mmdrop(mm); | |
50 | } | |
68e21be2 IM |
51 | |
52 | /** | |
53 | * mmget() - Pin the address space associated with a &struct mm_struct. | |
54 | * @mm: The address space to pin. | |
55 | * | |
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. | |
59 | * | |
60 | * Never use this function to pin this address space for an | |
61 | * unbounded/indefinite amount of time. | |
62 | * | |
63 | * Use mmput() to release the reference acquired by mmget(). | |
64 | * | |
65 | * See also <Documentation/vm/active_mm.txt> for an in-depth explanation | |
66 | * of &mm_struct.mm_count vs &mm_struct.mm_users. | |
67 | */ | |
68 | static inline void mmget(struct mm_struct *mm) | |
69 | { | |
70 | atomic_inc(&mm->mm_users); | |
71 | } | |
72 | ||
73 | static inline bool mmget_not_zero(struct mm_struct *mm) | |
74 | { | |
75 | return atomic_inc_not_zero(&mm->mm_users); | |
76 | } | |
77 | ||
78 | /* mmput gets rid of the mappings and all user-space */ | |
79 | extern void mmput(struct mm_struct *); | |
a1b2289c SY |
80 | #ifdef CONFIG_MMU |
81 | /* same as above but performs the slow path from the async context. Can | |
82 | * be called from the atomic context as well | |
83 | */ | |
84 | void mmput_async(struct mm_struct *); | |
85 | #endif | |
68e21be2 IM |
86 | |
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); | |
89 | /* | |
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 | |
92 | * succeeds. | |
93 | */ | |
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 *); | |
97 | ||
4240c8bf IM |
98 | #ifdef CONFIG_MEMCG |
99 | extern void mm_update_next_owner(struct mm_struct *mm); | |
100 | #else | |
101 | static inline void mm_update_next_owner(struct mm_struct *mm) | |
102 | { | |
103 | } | |
104 | #endif /* CONFIG_MEMCG */ | |
105 | ||
106 | #ifdef CONFIG_MMU | |
107 | extern void arch_pick_mmap_layout(struct mm_struct *mm); | |
108 | extern unsigned long | |
109 | arch_get_unmapped_area(struct file *, unsigned long, unsigned long, | |
110 | unsigned long, unsigned long); | |
111 | extern unsigned long | |
112 | arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr, | |
113 | unsigned long len, unsigned long pgoff, | |
114 | unsigned long flags); | |
115 | #else | |
116 | static inline void arch_pick_mmap_layout(struct mm_struct *mm) {} | |
117 | #endif | |
118 | ||
d026ce79 IM |
119 | static inline bool in_vfork(struct task_struct *tsk) |
120 | { | |
121 | bool ret; | |
122 | ||
123 | /* | |
124 | * need RCU to access ->real_parent if CLONE_VM was used along with | |
125 | * CLONE_PARENT. | |
126 | * | |
127 | * We check real_parent->mm == tsk->mm because CLONE_VFORK does not | |
128 | * imply CLONE_VM | |
129 | * | |
130 | * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus | |
131 | * ->real_parent is not necessarily the task doing vfork(), so in | |
132 | * theory we can't rely on task_lock() if we want to dereference it. | |
133 | * | |
134 | * And in this case we can't trust the real_parent->mm == tsk->mm | |
135 | * check, it can be false negative. But we do not care, if init or | |
136 | * another oom-unkillable task does this it should blame itself. | |
137 | */ | |
138 | rcu_read_lock(); | |
139 | ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm; | |
140 | rcu_read_unlock(); | |
141 | ||
142 | return ret; | |
143 | } | |
144 | ||
7dea19f9 MH |
145 | /* |
146 | * Applies per-task gfp context to the given allocation flags. | |
147 | * PF_MEMALLOC_NOIO implies GFP_NOIO | |
148 | * PF_MEMALLOC_NOFS implies GFP_NOFS | |
74444eda | 149 | */ |
7dea19f9 | 150 | static inline gfp_t current_gfp_context(gfp_t flags) |
74444eda | 151 | { |
7dea19f9 MH |
152 | /* |
153 | * NOIO implies both NOIO and NOFS and it is a weaker context | |
154 | * so always make sure it makes precendence | |
155 | */ | |
74444eda IM |
156 | if (unlikely(current->flags & PF_MEMALLOC_NOIO)) |
157 | flags &= ~(__GFP_IO | __GFP_FS); | |
7dea19f9 MH |
158 | else if (unlikely(current->flags & PF_MEMALLOC_NOFS)) |
159 | flags &= ~__GFP_FS; | |
74444eda IM |
160 | return flags; |
161 | } | |
162 | ||
d92a8cfc PZ |
163 | #ifdef CONFIG_LOCKDEP |
164 | extern void fs_reclaim_acquire(gfp_t gfp_mask); | |
165 | extern void fs_reclaim_release(gfp_t gfp_mask); | |
166 | #else | |
167 | static inline void fs_reclaim_acquire(gfp_t gfp_mask) { } | |
168 | static inline void fs_reclaim_release(gfp_t gfp_mask) { } | |
169 | #endif | |
170 | ||
74444eda IM |
171 | static inline unsigned int memalloc_noio_save(void) |
172 | { | |
173 | unsigned int flags = current->flags & PF_MEMALLOC_NOIO; | |
174 | current->flags |= PF_MEMALLOC_NOIO; | |
175 | return flags; | |
176 | } | |
177 | ||
178 | static inline void memalloc_noio_restore(unsigned int flags) | |
179 | { | |
180 | current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags; | |
181 | } | |
182 | ||
7dea19f9 MH |
183 | static inline unsigned int memalloc_nofs_save(void) |
184 | { | |
185 | unsigned int flags = current->flags & PF_MEMALLOC_NOFS; | |
186 | current->flags |= PF_MEMALLOC_NOFS; | |
187 | return flags; | |
188 | } | |
189 | ||
190 | static inline void memalloc_nofs_restore(unsigned int flags) | |
191 | { | |
192 | current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags; | |
193 | } | |
194 | ||
499118e9 VB |
195 | static inline unsigned int memalloc_noreclaim_save(void) |
196 | { | |
197 | unsigned int flags = current->flags & PF_MEMALLOC; | |
198 | current->flags |= PF_MEMALLOC; | |
199 | return flags; | |
200 | } | |
201 | ||
202 | static inline void memalloc_noreclaim_restore(unsigned int flags) | |
203 | { | |
204 | current->flags = (current->flags & ~PF_MEMALLOC) | flags; | |
205 | } | |
206 | ||
a961e409 MD |
207 | #ifdef CONFIG_MEMBARRIER |
208 | enum { | |
c5f58bd5 MD |
209 | MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0), |
210 | MEMBARRIER_STATE_PRIVATE_EXPEDITED = (1U << 1), | |
211 | MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY = (1U << 2), | |
212 | MEMBARRIER_STATE_GLOBAL_EXPEDITED = (1U << 3), | |
70216e18 MD |
213 | MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY = (1U << 4), |
214 | MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE = (1U << 5), | |
215 | }; | |
216 | ||
217 | enum { | |
218 | MEMBARRIER_FLAG_SYNC_CORE = (1U << 0), | |
a961e409 MD |
219 | }; |
220 | ||
3ccfebed MD |
221 | #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS |
222 | #include <asm/membarrier.h> | |
223 | #endif | |
224 | ||
70216e18 MD |
225 | static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm) |
226 | { | |
227 | if (likely(!(atomic_read(&mm->membarrier_state) & | |
228 | MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE))) | |
229 | return; | |
230 | sync_core_before_usermode(); | |
231 | } | |
232 | ||
a961e409 MD |
233 | static inline void membarrier_execve(struct task_struct *t) |
234 | { | |
235 | atomic_set(&t->mm->membarrier_state, 0); | |
236 | } | |
237 | #else | |
3ccfebed MD |
238 | #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS |
239 | static inline void membarrier_arch_switch_mm(struct mm_struct *prev, | |
240 | struct mm_struct *next, | |
241 | struct task_struct *tsk) | |
242 | { | |
243 | } | |
244 | #endif | |
a961e409 MD |
245 | static inline void membarrier_execve(struct task_struct *t) |
246 | { | |
247 | } | |
70216e18 MD |
248 | static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm) |
249 | { | |
250 | } | |
a961e409 MD |
251 | #endif |
252 | ||
6e84f315 | 253 | #endif /* _LINUX_SCHED_MM_H */ |