diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/rmap.c | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index b5c320f7d0a..38a336e2eea 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1131,6 +1131,20 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, return ret; } +static bool is_vma_temporary_stack(struct vm_area_struct *vma) +{ + int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP); + + if (!maybe_stack) + return false; + + if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) == + VM_STACK_INCOMPLETE_SETUP) + return true; + + return false; +} + /** * try_to_unmap_anon - unmap or unlock anonymous page using the object-based * rmap method @@ -1159,7 +1173,21 @@ static int try_to_unmap_anon(struct page *page, enum ttu_flags flags) list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { struct vm_area_struct *vma = avc->vma; - unsigned long address = vma_address(page, vma); + unsigned long address; + + /* + * During exec, a temporary VMA is setup and later moved. + * The VMA is moved under the anon_vma lock but not the + * page tables leading to a race where migration cannot + * find the migration ptes. Rather than increasing the + * locking requirements of exec(), migration skips + * temporary VMAs until after exec() completes. + */ + if (PAGE_MIGRATION && (flags & TTU_MIGRATION) && + is_vma_temporary_stack(vma)) + continue; + + address = vma_address(page, vma); if (address == -EFAULT) continue; ret = try_to_unmap_one(page, vma, address, flags); |