diff options
| -rw-r--r-- | include/linux/rmap.h | 1 | ||||
| -rw-r--r-- | mm/mmap.c | 3 | ||||
| -rw-r--r-- | mm/mremap.c | 14 | ||||
| -rw-r--r-- | mm/rmap.c | 45 |
4 files changed, 6 insertions, 57 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 3fce545..7f32cec 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -120,7 +120,6 @@ void anon_vma_init(void); /* create anon_vma_cachep */ int anon_vma_prepare(struct vm_area_struct *); void unlink_anon_vmas(struct vm_area_struct *); int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); -void anon_vma_moveto_tail(struct vm_area_struct *); int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); static inline void anon_vma_merge(struct vm_area_struct *vma, @@ -2378,8 +2378,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, */ VM_BUG_ON(faulted_in_anon_vma); *vmap = new_vma; - } else - anon_vma_moveto_tail(new_vma); + } } else { new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); if (new_vma) { diff --git a/mm/mremap.c b/mm/mremap.c index cc06d0e..5588bb6 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -74,6 +74,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, unsigned long new_addr) { struct address_space *mapping = NULL; + struct anon_vma *anon_vma = vma->anon_vma; struct mm_struct *mm = vma->vm_mm; pte_t *old_pte, *new_pte, pte; spinlock_t *old_ptl, *new_ptl; @@ -88,6 +89,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, mapping = vma->vm_file->f_mapping; mutex_lock(&mapping->i_mmap_mutex); } + if (anon_vma) + anon_vma_lock(anon_vma); /* * We don't have to worry about the ordering of src and dst @@ -114,6 +117,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, spin_unlock(new_ptl); pte_unmap(new_pte - 1); pte_unmap_unlock(old_pte - 1, old_ptl); + if (anon_vma) + anon_vma_unlock(anon_vma); if (mapping) mutex_unlock(&mapping->i_mmap_mutex); } @@ -221,15 +226,6 @@ static unsigned long move_vma(struct vm_area_struct *vma, moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len); if (moved_len < old_len) { /* - * Before moving the page tables from the new vma to - * the old vma, we need to be sure the old vma is - * queued after new vma in the same_anon_vma list to - * prevent SMP races with rmap_walk (that could lead - * rmap_walk to miss some page table). - */ - anon_vma_moveto_tail(vma); - - /* * On error, move entries back from new area to old, * which will succeed since page tables still there, * and then proceed to unmap new area instead of old. @@ -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. |
