2 * Copyright (C) 2014 Davidlohr Bueso.
4 #include <linux/sched.h>
6 #include <linux/vmacache.h>
9 * Flush vma caches for threads that share a given mm.
11 * The operation is safe because the caller holds the mmap_sem
12 * exclusively and other threads accessing the vma cache will
13 * have mmap_sem held at least for read, so no extra locking
14 * is required to maintain the vma cache.
16 void vmacache_flush_all(struct mm_struct *mm)
18 struct task_struct *g, *p;
20 count_vm_vmacache_event(VMACACHE_FULL_FLUSHES);
23 * Single threaded tasks need not iterate the entire
24 * list of process. We can avoid the flushing as well
25 * since the mm's seqnum was increased and don't have
26 * to worry about other threads' seqnum. Current's
27 * flush will occur upon the next lookup.
29 if (atomic_read(&mm->mm_users) == 1)
33 for_each_process_thread(g, p) {
35 * Only flush the vmacache pointers as the
36 * mm seqnum is already set and curr's will
37 * be set upon invalidation when the next
47 * This task may be accessing a foreign mm via (for example)
48 * get_user_pages()->find_vma(). The vmacache is task-local and this
49 * task's vmacache pertains to a different mm (ie, its own). There is
50 * nothing we can do here.
52 * Also handle the case where a kernel thread has adopted this mm via use_mm().
53 * That kernel thread's vmacache is not applicable to this mm.
55 static inline bool vmacache_valid_mm(struct mm_struct *mm)
57 return current->mm == mm && !(current->flags & PF_KTHREAD);
60 void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)
62 if (vmacache_valid_mm(newvma->vm_mm))
63 current->vmacache[VMACACHE_HASH(addr)] = newvma;
66 static bool vmacache_valid(struct mm_struct *mm)
68 struct task_struct *curr;
70 if (!vmacache_valid_mm(mm))
74 if (mm->vmacache_seqnum != curr->vmacache_seqnum) {
76 * First attempt will always be invalid, initialize
77 * the new cache for this task here.
79 curr->vmacache_seqnum = mm->vmacache_seqnum;
86 struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr)
90 if (!vmacache_valid(mm))
93 count_vm_vmacache_event(VMACACHE_FIND_CALLS);
95 for (i = 0; i < VMACACHE_SIZE; i++) {
96 struct vm_area_struct *vma = current->vmacache[i];
100 if (WARN_ON_ONCE(vma->vm_mm != mm))
102 if (vma->vm_start <= addr && vma->vm_end > addr) {
103 count_vm_vmacache_event(VMACACHE_FIND_HITS);
112 struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm,
118 if (!vmacache_valid(mm))
121 count_vm_vmacache_event(VMACACHE_FIND_CALLS);
123 for (i = 0; i < VMACACHE_SIZE; i++) {
124 struct vm_area_struct *vma = current->vmacache[i];
126 if (vma && vma->vm_start == start && vma->vm_end == end) {
127 count_vm_vmacache_event(VMACACHE_FIND_HITS);