Re: [PATCH 11/13] mm: add unsafe_follow_pfn

2020-10-08 Thread Jason Gunthorpe
On Wed, Oct 07, 2020 at 06:44:24PM +0200, Daniel Vetter wrote: > Way back it was a reasonable assumptions that iomem mappings never > change the pfn range they point at. But this has changed: > > - gpu drivers dynamically manage their memory nowadays, invalidating > ptes with unmap_mapping_range w

Re: [PATCH 11/13] mm: add unsafe_follow_pfn

2020-10-08 Thread Jason Gunthorpe
On Wed, Oct 07, 2020 at 08:10:34PM +0200, Daniel Vetter wrote: > On Wed, Oct 7, 2020 at 7:36 PM Jason Gunthorpe wrote: > > > > On Wed, Oct 07, 2020 at 06:44:24PM +0200, Daniel Vetter wrote: > > > Way back it was a reasonable assumptions that iomem mappings never > > > change the pfn range they poi

Re: [PATCH 11/13] mm: add unsafe_follow_pfn

2020-10-07 Thread Daniel Vetter
On Wed, Oct 7, 2020 at 9:00 PM Jason Gunthorpe wrote: > > On Wed, Oct 07, 2020 at 08:10:34PM +0200, Daniel Vetter wrote: > > On Wed, Oct 7, 2020 at 7:36 PM Jason Gunthorpe wrote: > > > > > > On Wed, Oct 07, 2020 at 06:44:24PM +0200, Daniel Vetter wrote: > > > > Way back it was a reasonable assump

Re: [PATCH 11/13] mm: add unsafe_follow_pfn

2020-10-07 Thread Daniel Vetter
On Wed, Oct 7, 2020 at 7:36 PM Jason Gunthorpe wrote: > > On Wed, Oct 07, 2020 at 06:44:24PM +0200, Daniel Vetter wrote: > > Way back it was a reasonable assumptions that iomem mappings never > > change the pfn range they point at. But this has changed: > > > > - gpu drivers dynamically manage the

[PATCH 11/13] mm: add unsafe_follow_pfn

2020-10-07 Thread Daniel Vetter
Way back it was a reasonable assumptions that iomem mappings never change the pfn range they point at. But this has changed: - gpu drivers dynamically manage their memory nowadays, invalidating ptes with unmap_mapping_range when buffers get moved - contiguous dma allocations have moved from dedic