diff options
| -rw-r--r-- | mm/mincore.c | 102 |
1 files changed, 76 insertions, 26 deletions
diff --git a/mm/mincore.c b/mm/mincore.c index 8aca6f7..95c5f49 100644 --- a/mm/mincore.c +++ b/mm/mincore.c @@ -12,6 +12,8 @@ #include <linux/mm.h> #include <linux/mman.h> #include <linux/syscalls.h> +#include <linux/swap.h> +#include <linux/swapops.h> #include <asm/uaccess.h> #include <asm/pgtable.h> @@ -22,14 +24,22 @@ * and is up to date; i.e. that no page-in operation would be required * at this time if an application were to map and access this page. */ -static unsigned char mincore_page(struct vm_area_struct * vma, - unsigned long pgoff) +static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff) { unsigned char present = 0; - struct address_space * as = vma->vm_file->f_mapping; - struct page * page; + struct page *page; - page = find_get_page(as, pgoff); + /* + * When tmpfs swaps out a page from a file, any process mapping that + * file will not get a swp_entry_t in its pte, but rather it is like + * any other file mapping (ie. marked !present and faulted in with + * tmpfs's .nopage). So swapped out tmpfs mappings are tested here. + * + * However when tmpfs moves the page from pagecache and into swapcache, + * it is still in core, but the find_get_page below won't find it. + * No big deal, but make a note of it. + */ + page = find_get_page(mapping, pgoff); if (page) { present = PageUptodate(page); page_cache_release(page); @@ -45,7 +55,14 @@ static unsigned char mincore_page(struct vm_area_struct * vma, */ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pages) { - unsigned long i, nr, pgoff; + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *ptep; + spinlock_t *ptl; + unsigned long nr; + int i; + pgoff_t pgoff; struct vm_area_struct *vma = find_vma(current->mm, addr); /* @@ -56,31 +73,64 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag return -ENOMEM; /* - * Ok, got it. But check whether it's a segment we support - * mincore() on. Right now, we don't do any anonymous mappings. - * - * FIXME: This is just stupid. And returning ENOMEM is - * stupid too. We should just look at the page tables. But - * this is what we've traditionally done, so we'll just - * continue doing it. + * Calculate how many pages there are left in the last level of the + * PTE array for our address. */ - if (!vma->vm_file) - return -ENOMEM; - - /* - * Calculate how many pages there are left in the vma, and - * what the pgoff is for our address. - */ - nr = (vma->vm_end - addr) >> PAGE_SHIFT; + nr = PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1)); if (nr > pages) nr = pages; - pgoff = (addr - vma->vm_start) >> PAGE_SHIFT; - pgoff += vma->vm_pgoff; + pgd = pgd_offset(vma->vm_mm, addr); + if (pgd_none_or_clear_bad(pgd)) + goto none_mapped; + pud = pud_offset(pgd, addr); + if (pud_none_or_clear_bad(pud)) + goto none_mapped; + pmd = pmd_offset(pud, addr); + if (pmd_none_or_clear_bad(pmd)) + goto none_mapped; + + ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + for (i = 0; i < nr; i++, ptep++, addr += PAGE_SIZE) { + unsigned char present; + pte_t pte = *ptep; + + if (pte_present(pte)) { + present = 1; + + } else if (pte_none(pte)) { + if (vma->vm_file) { + pgoff = linear_page_index(vma, addr); + present = mincore_page(vma->vm_file->f_mapping, + pgoff); + } else + present = 0; + + } else if (pte_file(pte)) { + pgoff = pte_to_pgoff(pte); + present = mincore_page(vma->vm_file->f_mapping, pgoff); + + } else { /* pte is a swap entry */ + swp_entry_t entry = pte_to_swp_entry(pte); + if (is_migration_entry(entry)) { + /* migration entries are always uptodate */ + present = 1; + } else { + pgoff = entry.val; + present = mincore_page(&swapper_space, pgoff); + } + } + } + pte_unmap_unlock(ptep-1, ptl); + + return nr; - /* And then we just fill the sucker in.. */ - for (i = 0 ; i < nr; i++, pgoff++) - vec[i] = mincore_page(vma, pgoff); +none_mapped: + if (vma->vm_file) { + pgoff = linear_page_index(vma, addr); + for (i = 0; i < nr; i++, pgoff++) + vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff); + } return nr; } |