/* * Copyright (C) 2014 Davidlohr Bueso. */ #include #include #include /* * Flush vma caches for threads that share a given mm. * * The operation is safe because the caller holds the mmap_sem * exclusively and other threads accessing the vma cache will * have mmap_sem held at least for read, so no extra locking * is required to maintain the vma cache. */ void vmacache_flush_all(struct mm_struct *mm) { struct task_struct *g, *p; count_vm_vmacache_event(VMACACHE_FULL_FLUSHES); /* * Single threaded tasks need not iterate the entire * list of process. We can avoid the flushing as well * since the mm's seqnum was increased and don't have * to worry about other threads' seqnum. Current's * flush will occur upon the next lookup. */ if (atomic_read(&mm->mm_users) == 1) return; rcu_read_lock(); for_each_process_thread(g, p) { /* * Only flush the vmacache pointers as the * mm seqnum is already set and curr's will * be set upon invalidation when the next * lookup is done. */ if (mm == p->mm) vmacache_flush(p); } rcu_read_unlock(); } /* * This task may be accessing a foreign mm via (for example) * get_user_pages()->find_vma(). The vmacache is task-local and this * task's vmacache pertains to a different mm (ie, its own). There is * nothing we can do here. * * Also handle the case where a kernel thread has adopted this mm via use_mm(). * That kernel thread's vmacache is not applicable to this mm. */ static inline bool vmacache_valid_mm(struct mm_struct *mm) { return current->mm == mm && !(current->flags & PF_KTHREAD); } void vmacache_update(unsigned long addr, struct vm_area_struct *newvma) { if (vmacache_valid_mm(newvma->vm_mm)) current->vmacache[VMACACHE_HASH(addr)] = newvma; } static bool vmacache_valid(struct mm_struct *mm) { struct task_struct *curr; if (!vmacache_valid_mm(mm)) return false; curr = current; if (mm->vmacache_seqnum != curr->vmacache_seqnum) { /* * First attempt will always be invalid, initialize * the new cache for this task here. */ curr->vmacache_seqnum = mm->vmacache_seqnum; vmacache_flush(curr); return false; } return true; } struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr) { int i; count_vm_vmacache_event(VMACACHE_FIND_CALLS); if (!vmacache_valid(mm)) return NULL; for (i = 0; i < VMACACHE_SIZE; i++) { struct vm_area_struct *vma = current->vmacache[i]; if (!vma) continue; if (WARN_ON_ONCE(vma->vm_mm != mm)) break; if (vma->vm_start <= addr && vma->vm_end > addr) { count_vm_vmacache_event(VMACACHE_FIND_HITS); return vma; } } return NULL; } #ifndef CONFIG_MMU struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm, unsigned long start, unsigned long end) { int i; count_vm_vmacache_event(VMACACHE_FIND_CALLS); if (!vmacache_valid(mm)) return NULL; for (i = 0; i < VMACACHE_SIZE; i++) { struct vm_area_struct *vma = current->vmacache[i]; if (vma && vma->vm_start == start && vma->vm_end == end) { count_vm_vmacache_event(VMACACHE_FIND_HITS); return vma; } } return NULL; } #endif =c56108b58ab870892277940a1def0d6b153f3e26'>perf/builtin-kmem.c

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