On Tue, 3 Apr 2018, David Rientjes 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) > Ugh, I think there are a number of other places where this is needed as well in mm/mmap.c. I think it would be better to just create a new alloc_vma(unsigned long flags) that all vma allocators can use and for CONFIG_SPECULATIVE_PAGE_FAULT will initialize the seqcount_t and atomic_t.