Re: [PATCH 03/13] mm/munlock: delete munlock_vma_pages_all(), allow oomreap

Vlastimil Babka
2022-02-10T15:30:38Z

On 2/6/22 22:34, Hugh Dickins wrote:
> munlock_vma_pages_range() will still be required, when munlocking but
> not munmapping a set of pages; but when unmapping a pte, the mlock count
> will be maintained in much the same way as it will be maintained when
> mapping in the pte. Which removes the need for munlock_vma_pages_all()
> on mlocked vmas when munmapping or exiting: eliminating the catastrophic
> contention on i_mmap_rwsem, and the need for page lock on the pages.
>
> There is still a need to update locked_vm accounting according to the
> munmapped vmas when munmapping: do that in detach_vmas_to_be_unmapped().
> exit_mmap() does not need locked_vm updates, so delete unlock_range().
>
> And wasn't I the one who forbade the OOM reaper to attack mlocked vmas,
> because of the uncertainty in blocking on all those page locks?
> No fear of that now, so permit the OOM reaper on mlocked vmas.
>
> Signed-off-by: Hugh Dickins <hughd@google.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>