On Wed, 28 Mar 2018, Laurent Dufour wrote:
> On 26/03/2018 00:10, David Rientjes wrote:
> > On Wed, 21 Mar 2018, Laurent Dufour wrote:
> >
> >> I found the root cause of this lockdep warning.
> >>
> >> In mmap_region(), unmap_region() may be called while vma_link() has not
> >> been
> >> called. This happens during the error path if call_mmap() failed.
> >>
> >> The only to fix that particular case is to call
> >> seqcount_init(&vma->vm_sequence) when initializing the vma in
> >> mmap_region().
> >>
> >
> > Ack, although that would require a fixup to dup_mmap() as well.
>
> You're right, I'll fix that too.
>
I also think the following is needed:
diff --git a/fs/exec.c b/fs/exec.c
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -312,6 +312,10 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS |
VM_STACK_INCOMPLETE_SETUP;
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
INIT_LIST_HEAD(&vma->anon_vma_chain);
+#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
+ seqcount_init(&vma->vm_sequence);
+ atomic_set(&vma->vm_ref_count, 0);
+#endif
err = insert_vm_struct(mm, vma);
if (err)
