Commit d4c54919ed86302094c0ca7d48a8cbd4ee753e92
Committed by
Linus Torvalds
Linus Torvalds
1 parent
d54d14bfb4
Exists in
ti-lsk-linux-4.1.y
and in
12 other branches
mm: add !pte_present() check on existing hugetlb_entry callbacks
The age table walker doesn't check non-present hugetlb entry in common path, so hugetlb_entry() callbacks must check it. The reason for this behavior is that some callers want to handle it in its own way. [ I think that reason is bogus, btw - it should just do what the regular code does, which is to call the "pte_hole()" function for such hugetlb entries - Linus] However, some callers don't check it now, which causes unpredictable result, for example when we have a race between migrating hugepage and reading /proc/pid/numa_maps. This patch fixes it by adding !pte_present checks on buggy callbacks. This bug exists for years and got visible by introducing hugepage migration. ChangeLog v2: - fix if condition (check !pte_present() instead of pte_present()) Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Backported to 3.15. Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org> ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Showing 2 changed files with 6 additions and 2 deletions Side-by-side Diff
fs/proc/task_mmu.c
mm/mempolicy.c
| ... | ... | @@ -526,9 +526,13 @@ |
| 526 | 526 | int nid; |
| 527 | 527 | struct page *page; |
| 528 | 528 | spinlock_t *ptl; |
| 529 | + pte_t entry; | |
| 529 | 530 | |
| 530 | 531 | ptl = huge_pte_lock(hstate_vma(vma), vma->vm_mm, (pte_t *)pmd); |
| 531 | - page = pte_page(huge_ptep_get((pte_t *)pmd)); | |
| 532 | + entry = huge_ptep_get((pte_t *)pmd); | |
| 533 | + if (!pte_present(entry)) | |
| 534 | + goto unlock; | |
| 535 | + page = pte_page(entry); | |
| 532 | 536 | nid = page_to_nid(page); |
| 533 | 537 | if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT)) |
| 534 | 538 | goto unlock; |
