cregit-Linux how code gets into the kernel

Release 4.12 mm/vmacache.c

Directory: mm
/*
 * Copyright (C) 2014 Davidlohr Bueso.
 */
#include <linux/sched/signal.h>
#include <linux/sched/task.h>
#include <linux/mm.h>
#include <linux/vmacache.h>

/*
 * 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(); }

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Davidlohr Bueso A65100.00%3100.00%
Total65100.00%3100.00%

/* * 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); }

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Davidlohr Bueso A28100.00%2100.00%
Total28100.00%2100.00%


void vmacache_update(unsigned long addr, struct vm_area_struct *newvma) { if (vmacache_valid_mm(newvma->vm_mm)) current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma; }

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Davidlohr Bueso A3594.59%150.00%
Ingo Molnar25.41%150.00%
Total37100.00%2100.00%


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; }

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Davidlohr Bueso A6191.04%150.00%
Ingo Molnar68.96%150.00%
Total67100.00%2100.00%


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.vmas[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; }

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PersonTokensPropCommitsCommitProp
Davidlohr Bueso A8577.98%240.00%
Linus Torvalds1715.60%120.00%
Alexey Dobriyan54.59%120.00%
Ingo Molnar21.83%120.00%
Total109100.00%5100.00%

#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.vmas[i]; if (vma && vma->vm_start == start && vma->vm_end == end) { count_vm_vmacache_event(VMACACHE_FIND_HITS); return vma; } } return NULL; }

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PersonTokensPropCommitsCommitProp
Davidlohr Bueso A9092.78%250.00%
Alexey Dobriyan55.15%125.00%
Ingo Molnar22.06%125.00%
Total97100.00%4100.00%

#endif

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Davidlohr Bueso A38089.83%550.00%
Linus Torvalds174.02%110.00%
Ingo Molnar163.78%330.00%
Alexey Dobriyan102.36%110.00%
Total423100.00%10100.00%
Directory: mm
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