Re: [PATCH v16 13/25] mm: pagewalk: Don't lock PTEs for walk_page_range_novma()

[Luc Van Oostenryck]

On Wed, Dec 11, 2019 at 03:54:06PM +0000, Steven Price wrote:
> On 10/12/2019 11:23, kbuild test robot wrote:
> >>> include/linux/spinlock.h:378:9: sparse: sparse: context imbalance in 'walk_pte_range' - unexpected unlock
> 
> I believe this is a false positive (although the trace here is useless).
> This patch adds a conditional lock/unlock:
> 
> pte = walk->no_vma ? pte_offset_map(pmd, addr) :
> 		     pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
> ...
> if (!walk->no_vma)
> 	spin_unlock(ptl);
> pte_unmap(pte);
> 
> I'm not sure how to match sparse happy about that. Is the only option to
> have two versions of the walk_pte_range() function? One which takes the
> lock and one which doesn't.

Yes.

-- Luc