[PATCH] mm/hmm: hmm_range_fault handle pages swapped out

[Jason Gunthorpe]

On Thu, Aug 15, 2019 at 08:52:56PM +0000, Yang, Philip wrote:
> hmm_range_fault may return NULL pages because some of pfns are equal to
> HMM_PFN_NONE. This happens randomly under memory pressure. The reason is
> for swapped out page pte path, hmm_vma_handle_pte doesn't update fault
> variable from cpu_flags, so it failed to call hmm_vam_do_fault to swap
> the page in.
>
> The fix is to call hmm_pte_need_fault to update fault variable.

> Change-Id: I2e8611485563d11d938881c18b7935fa1e7c91ee

I'll fix it for you but please be careful not to send Change-id's to
the public lists.

Also what is the Fixes line for this?

> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
>  mm/hmm.c | 3 +++
>  1 file changed, 3 insertions(+)

Ralph has also been looking at this area also so I'll give him a bit
to chime in, otherwise with Jerome's review this looks OK to go to
linux-next

Thanks,
Jason