Ahh. Good catch. So I can't actually do that anon_vma_prepare() thing in
__insert_vm_struct.
It should be simple enough to just move it into the caller, just after it
releases that lock. There's only one user of that __insert_vm_struct()
anyway. You can do it yourself, or you can replace my previous patch with
this..
[ The patch below also makes it warn once and return SIGBUS for the case
where there is no anon_vma. I decided I still want to hear about it if
there might be some path that tries to insert a vma on its own ]
Linus
---
mm/memory.c | 12 +++---------
mm/mmap.c | 17 ++++-------------
2 files changed, 7 insertions(+), 22 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 833952d..08d4423 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2223,9 +2223,6 @@ reuse:
gotten:
pte_unmap_unlock(page_table, ptl);
- if (unlikely(anon_vma_prepare(vma)))
- goto oom;
-
if (is_zero_pfn(pte_pfn(orig_pte))) {
new_page = alloc_zeroed_user_highpage_movable(vma, address);
if (!new_page)
@@ -2766,8 +2763,6 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
/* Allocate our own private page. */
pte_unmap(page_table);
- if (unlikely(anon_vma_prepare(vma)))
- goto oom;
page = alloc_zeroed_user_highpage_movable(vma, address);
if (!page)
goto oom;
@@ -2863,10 +2858,6 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
if (flags & FAULT_FLAG_WRITE) {
if (!(vma->vm_flags & VM_SHARED)) {
anon = 1;
- if (unlikely(anon_vma_prepare(vma))) {
- ret = VM_FAULT_OOM;
- goto out;
- }
page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
vma, address);
if (!page) {
@@ -3115,6 +3106,9 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
pmd_t *pmd;
pte_t *pte;
+ if (WARN_ONCE(!vma->anon_vma, "Mapping with no anon_vma"))
+ return VM_FAULT_SIGBUS;
+
__set_current_state(TASK_RUNNING);
count_vm_event(PGFAULT);
diff --git a/mm/mmap.c b/mm/mmap.c
index 75557c6..82392c2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -463,6 +463,8 @@ static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
mm->map_count++;
validate_mm(mm);
+
+ anon_vma_prepare(vma);
}
/*
@@ -628,6 +630,8 @@ again: remove_next = 1 + (end > next->vm_end);
if (mapping)
spin_unlock(&mapping->i_mmap_lock);
+ anon_vma_prepare(vma);
+
if (remove_next) {
if (file) {
fput(file);
@@ -1674,12 +1678,6 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
if (!(vma->vm_flags & VM_GROWSUP))
return -EFAULT;
- /*
- * We must make sure the anon_vma is allocated
- * so that the anon_vma locking is not a noop.
- */
- if (unlikely(anon_vma_prepare(vma)))
- return -ENOMEM;
anon_vma_lock(vma);
/*
@@ -1720,13 +1718,6 @@ static int expand_downwards(struct vm_area_struct *vma,
{
int error;
- /*
- * We must make sure the anon_vma is allocated
- * so that the anon_vma locking is not a noop.
- */
- if (unlikely(anon_vma_prepare(vma)))
- return -ENOMEM;
-
address &= PAGE_MASK;
error = security_file_mmap(NULL, 0, 0, 0, address, 1);
if (error)
--
