diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 45 |
1 files changed, 0 insertions, 45 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 7b5b51d25fc5..8cbd62fde0f1 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -269,51 +269,6 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) } /* - * Some rmap walk that needs to find all ptes/hugepmds without false - * negatives (like migrate and split_huge_page) running concurrent - * with operations that copy or move pagetables (like mremap() and - * fork()) to be safe. They depend on the anon_vma "same_anon_vma" - * list to be in a certain order: the dst_vma must be placed after the - * src_vma in the list. This is always guaranteed by fork() but - * mremap() needs to call this function to enforce it in case the - * dst_vma isn't newly allocated and chained with the anon_vma_clone() - * function but just an extension of a pre-existing vma through - * vma_merge. - * - * NOTE: the same_anon_vma list can still be changed by other - * processes while mremap runs because mremap doesn't hold the - * anon_vma mutex to prevent modifications to the list while it - * runs. All we need to enforce is that the relative order of this - * process vmas isn't changing (we don't care about other vmas - * order). Each vma corresponds to an anon_vma_chain structure so - * there's no risk that other processes calling anon_vma_moveto_tail() - * and changing the same_anon_vma list under mremap() will screw with - * the relative order of this process vmas in the list, because we - * they can't alter the order of any vma that belongs to this - * process. And there can't be another anon_vma_moveto_tail() running - * concurrently with mremap() coming from this process because we hold - * the mmap_sem for the whole mremap(). fork() ordering dependency - * also shouldn't be affected because fork() only cares that the - * parent vmas are placed in the list before the child vmas and - * anon_vma_moveto_tail() won't reorder vmas from either the fork() - * parent or child. - */ -void anon_vma_moveto_tail(struct vm_area_struct *dst) -{ - struct anon_vma_chain *pavc; - struct anon_vma *root = NULL; - - list_for_each_entry_reverse(pavc, &dst->anon_vma_chain, same_vma) { - struct anon_vma *anon_vma = pavc->anon_vma; - VM_BUG_ON(pavc->vma != dst); - root = lock_anon_vma_root(root, anon_vma); - list_del(&pavc->same_anon_vma); - list_add_tail(&pavc->same_anon_vma, &anon_vma->head); - } - unlock_anon_vma_root(root); -} - -/* * Attach vma to its own anon_vma, as well as to the anon_vmas that * the corresponding VMA in the parent process is attached to. * Returns 0 on success, non-zero on failure. |