lkml.org 
[lkml]   [2018]   [Apr]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [mm] b1f0502d04: INFO:trying_to_register_non-static_key
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.

\
 
 \ /
  Last update: 2018-04-04 03:03    [W:0.103 / U:3.768 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site