On Wed, Mar 11, 2020 at 03:35:00PM -0300, Jason Gunthorpe wrote:
> @@ -694,6 +672,15 @@ long hmm_range_fault(struct hmm_range *range, unsigned int flags)
> return -EBUSY;
> ret = walk_page_range(mm, hmm_vma_walk.last, range->end,
> &hmm_walk_ops, &hmm_vma_walk);
> + /*
> + * A pgmap is kept cached in the hmm_vma_walk to avoid expensive
> + * searching in the probably common case that the pgmap is the
> + * same for the entire requested range.
> + */
> + if (hmm_vma_walk.pgmap) {
> + put_dev_pagemap(hmm_vma_walk.pgmap);
> + hmm_vma_walk.pgmap = NULL;
> + }
> } while (ret == -EBUSY);
In which case it should only be put on return, and not for every loop.
I still think the right fix is to just delete all the unused and broken
pgmap handling code. If we ever need to add it back it can be added
in a proper understood and tested way.
