Re: [PATCH] mm/hmm: Fix bad subpage pointer in try_to_unmap_one

From: Ralph Campbell
Date: Tue Jul 09 2019 - 21:25:00 EST

On 7/9/19 5:28 PM, Andrew Morton wrote:
On Tue, 9 Jul 2019 15:35:56 -0700 Ralph Campbell <rcampbell@xxxxxxxxxx> wrote:

When migrating a ZONE device private page from device memory to system
memory, the subpage pointer is initialized from a swap pte which computes
an invalid page pointer. A kernel panic results such as:

BUG: unable to handle page fault for address: ffffea1fffffffc8

Initialize subpage correctly before calling page_remove_rmap().

I think this is

Fixes: a5430dda8a3a1c ("mm/migrate: support un-addressable ZONE_DEVICE page in migration")
Cc: stable


Yes. Can you add this or should I send a v2?