static void check_mm(struct mm_struct *mm)
{
int i;
for (i = 0; i < NR_MM_COUNTERS; i++) {
long x = atomic_long_read(&mm->rss_stat.count[i]);
if (unlikely(x))
printk(KERN_ALERT "BUG: Bad rss-counter state "
"mm:%p idx:%d val:%ld\n", mm, i, x);
}
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
#endif
}
/**
* walk_page_range - walk page table with caller specific callbacks
*
* Recursively walk the page table tree of the process represented by @walk->mm
* within the virtual address range [@start, @end). During walking, we can do
* some caller-specific works for each entry, by setting up pmd_entry(),
* pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
* callbacks, the associated entries/pages are just ignored.
* The return values of these callbacks are commonly defined like below:
* - 0 : succeeded to handle the current entry, and if you don't reach the
* end address yet, continue to walk.
* - >0 : succeeded to handle the current entry, and return to the caller
* with caller specific value.
* - <0 : failed to handle the current entry, and return to the caller
* with error code.
*
* Before starting to walk page table, some callers want to check whether
* they really want to walk over the current vma, typically by checking
* its vm_flags. walk_page_test() and @walk->test_walk() are used for this
* purpose.
*
* struct mm_walk keeps current values of some common data like vma and pmd,
* which are useful for the access from callbacks. If you want to pass some
* caller-specific data to callbacks, @walk->private should be helpful.
*
* Locking:
* Callers of walk_page_range() and walk_page_vma() should hold
* @walk->mm->mmap_sem, because these function traverse vma list and/or
* access to vma's data.
*/
int walk_page_range(unsigned long start, unsigned long end,
struct mm_walk *walk)
{
int err = 0;
unsigned long next;
struct vm_area_struct *vma;
if (start >= end)
return -EINVAL;
if (!walk->mm)
return -EINVAL;
VM_BUG_ON_MM(!rwsem_is_locked(&walk->mm->mmap_sem), walk->mm);
vma = find_vma(walk->mm, start);
do {
if (!vma) { /* after the last vma */
walk->vma = NULL;
next = end;
} else if (start < vma->vm_start) { /* outside vma */
walk->vma = NULL;
next = min(end, vma->vm_start);
} else { /* inside vma */
walk->vma = vma;
next = min(end, vma->vm_end);
vma = vma->vm_next;
err = walk_page_test(start, next, walk);
if (err > 0) {
/*
* positive return values are purely for
* controlling the pagewalk, so should never
* be passed to the callers.
*/
err = 0;
continue;
}
if (err < 0)
break;
}
if (walk->vma || walk->pte_hole)
err = __walk_page_range(start, next, walk);
if (err)
break;
} while (start = next, start < end);
return err;
}
/**
* walk_page_range - walk a memory map's page tables with a callback
* @addr: starting address
* @end: ending address
* @walk: set of callbacks to invoke for each level of the tree
*
* Recursively walk the page table for the memory area in a VMA,
* calling supplied callbacks. Callbacks are called in-order (first
* PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
* etc.). If lower-level callbacks are omitted, walking depth is reduced.
*
* Each callback receives an entry pointer and the start and end of the
* associated range, and a copy of the original mm_walk for access to
* the ->private or ->mm fields.
*
* Usually no locks are taken, but splitting transparent huge page may
* take page table lock. And the bottom level iterator will map PTE
* directories from highmem if necessary.
*
* If any callback returns a non-zero value, the walk is aborted and
* the return value is propagated back to the caller. Otherwise 0 is returned.
*
* walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry
* is !NULL.
*/
int walk_page_range(unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
pgd_t *pgd;
unsigned long next;
int err = 0;
if (addr >= end)
return err;
if (!walk->mm)
return -EINVAL;
VM_BUG_ON_MM(!rwsem_is_locked(&walk->mm->mmap_sem), walk->mm);
pgd = pgd_offset(walk->mm, addr);
do {
struct vm_area_struct *vma = NULL;
next = pgd_addr_end(addr, end);
/*
* This function was not intended to be vma based.
* But there are vma special cases to be handled:
* - hugetlb vma's
* - VM_PFNMAP vma's
*/
vma = find_vma(walk->mm, addr);
if (vma) {
/*
* There are no page structures backing a VM_PFNMAP
* range, so do not allow split_huge_page_pmd().
*/
if ((vma->vm_start <= addr) &&
(vma->vm_flags & VM_PFNMAP)) {
next = vma->vm_end;
pgd = pgd_offset(walk->mm, next);
continue;
}
/*
* Handle hugetlb vma individually because pagetable
* walk for the hugetlb page is dependent on the
* architecture and we can't handled it in the same
* manner as non-huge pages.
*/
if (walk->hugetlb_entry && (vma->vm_start <= addr) &&
is_vm_hugetlb_page(vma)) {
if (vma->vm_end < next)
next = vma->vm_end;
/*
* Hugepage is very tightly coupled with vma,
* so walk through hugetlb entries within a
* given vma.
*/
err = walk_hugetlb_range(vma, addr, next, walk);
if (err)
break;
pgd = pgd_offset(walk->mm, next);
continue;
}
}
if (pgd_none_or_clear_bad(pgd)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
if (err)
break;
pgd++;
continue;
}
if (walk->pgd_entry)
err = walk->pgd_entry(pgd, addr, next, walk);
if (!err &&
(walk->pud_entry || walk->pmd_entry || walk->pte_entry))
err = walk_pud_range(pgd, addr, next, walk);
if (err)
break;
pgd++;
} while (addr = next, addr < end);
return err;
}
