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Date:   Tue, 3 Apr 2018 17:48:34 -0700 (PDT)
From:   David Rientjes <rientjes@google.com>
To:     Laurent Dufour <ldufour@linux.vnet.ibm.com>
cc:     kernel test robot <fengguang.wu@intel.com>,
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Subject: Re: [mm] b1f0502d04: INFO:trying_to_register_non-static_key
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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)