[PATCH] mm: mincore anon
Make mincore work for anon mappings, nonlinear, and migration entries.
Based on patch from Linus Torvalds <torvalds@linux-foundation.org>.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 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 @@
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;
- /* And then we just fill the sucker in.. */
- for (i = 0 ; i < nr; i++, pgoff++)
- vec[i] = mincore_page(vma, pgoff);
+ 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;
+
+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;
}