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