Re: [PATCH] mm/khugepaged: Fix ->anon_vma race

[Kirill A. Shutemov]

On Fri, Jan 13, 2023 at 08:28:59PM +0100, Jann Horn wrote:
> No, that lockdep assert has to be there. Page table traversal is
> allowed under any one of the mmap lock, the anon_vma lock (if the VMA
> is associated with an anon_vma), and the mapping lock (if the VMA is
> associated with a mapping); and so to be able to remove page tables,
> we must hold all three of them.

Okay, that's fair. I agree with the patch now. Maybe adjust the commit
message a bit?

Anyway:

Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>

BTW, I've noticied that you recently added tlb_remove_table_sync_one().
I'm not sure why it is needed. Why IPI in pmdp_collapse_flush() in not
good enough to serialize against GUP fast?

-- 
  Kiryl Shutsemau / Kirill A. Shutemov