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

2019-07-16 Thread Andrew Morton
On Mon, 15 Jul 2019 17:38:04 -0700 Ralph Campbell wrote: > I'm not surprised at the confusion. It took me quite awhile to > understand how migrate_vma() works with ZONE_DEVICE private memory. > > ... > > I see Christoph Hellwig got confused by this too [1]. While making such discoveries, pleas

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

2019-07-16 Thread Jerome Glisse
On Mon, Jul 15, 2019 at 11:14:31PM -0700, John Hubbard wrote: > On 7/15/19 5:38 PM, Ralph Campbell wrote: > > On 7/15/19 4:34 PM, John Hubbard wrote: > > > On 7/15/19 3:00 PM, Andrew Morton wrote: > > > > On Tue, 9 Jul 2019 18:24:57 -0700 Ralph Campbell > > > > wrote: > > > > > > > >   mm/rmap.c

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

2019-07-15 Thread John Hubbard
On 7/15/19 5:38 PM, Ralph Campbell wrote: On 7/15/19 4:34 PM, John Hubbard wrote: On 7/15/19 3:00 PM, Andrew Morton wrote: On Tue, 9 Jul 2019 18:24:57 -0700 Ralph Campbell wrote:   mm/rmap.c |    1 +   1 file changed, 1 insertion(+) --- a/mm/rmap.c~mm-hmm-fix-bad-subpage-pointer-in-try_to_un

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

2019-07-15 Thread Ralph Campbell
On 7/15/19 4:34 PM, John Hubbard wrote: On 7/15/19 3:00 PM, Andrew Morton wrote: On Tue, 9 Jul 2019 18:24:57 -0700 Ralph Campbell wrote: On 7/9/19 5:28 PM, Andrew Morton wrote: On Tue, 9 Jul 2019 15:35:56 -0700 Ralph Campbell wrote: When migrating a ZONE device private page from device

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

2019-07-15 Thread John Hubbard
On 7/15/19 3:00 PM, Andrew Morton wrote: > On Tue, 9 Jul 2019 18:24:57 -0700 Ralph Campbell wrote: > >> >> On 7/9/19 5:28 PM, Andrew Morton wrote: >>> On Tue, 9 Jul 2019 15:35:56 -0700 Ralph Campbell >>> wrote: >>> When migrating a ZONE device private page from device memory to system

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

2019-07-15 Thread Andrew Morton
On Tue, 9 Jul 2019 18:24:57 -0700 Ralph Campbell wrote: > > On 7/9/19 5:28 PM, Andrew Morton wrote: > > On Tue, 9 Jul 2019 15:35:56 -0700 Ralph Campbell > > wrote: > > > >> When migrating a ZONE device private page from device memory to system > >> memory, the subpage pointer is initialized f

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

2019-07-09 Thread Ralph Campbell
On 7/9/19 5:28 PM, Andrew Morton wrote: On Tue, 9 Jul 2019 15:35:56 -0700 Ralph Campbell 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 suc

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

2019-07-09 Thread Andrew Morton
On Tue, 9 Jul 2019 15:35:56 -0700 Ralph Campbell 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 f

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

2019-07-09 Thread Ralph Campbell
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: ea1fffc8 Initialize subpage correctly bef