Re: [PATCH v3 5/8] mm: Device exclusive memory access

2021-03-03 Thread Alistair Popple
On Tuesday, 2 March 2021 11:41:52 PM AEDT Jason Gunthorpe wrote: > > However try_to_protect() scans the PTEs again under the PTL so checking the > > mapping of interest actually gets replaced during the rmap walk seems like a > > reasonable solution. Thanks for the comments. > > It does seem c

Re: [PATCH v3 5/8] mm: Device exclusive memory access

2021-03-02 Thread Jason Gunthorpe
On Tue, Mar 02, 2021 at 07:57:58PM +1100, Alistair Popple wrote: > The intent was a driver could use HMM or some other mechanism to keep PTEs > synchronised if required. However I just looked at patch 8 in the series > again > and it appears I got this wrong when converting from the old migrati

Re: [PATCH v3 5/8] mm: Device exclusive memory access

2021-03-02 Thread Alistair Popple
On Tuesday, 2 March 2021 11:05:59 AM AEDT Jason Gunthorpe wrote: > On Fri, Feb 26, 2021 at 06:18:29PM +1100, Alistair Popple wrote: > > > +/** > > + * make_device_exclusive_range() - Mark a range for exclusive use by a device > > + * @mm: mm_struct of assoicated target process > > + * @start: sta

Re: [PATCH v3 5/8] mm: Device exclusive memory access

2021-03-01 Thread Jason Gunthorpe
On Fri, Feb 26, 2021 at 06:18:29PM +1100, Alistair Popple wrote: > +/** > + * make_device_exclusive_range() - Mark a range for exclusive use by a device > + * @mm: mm_struct of assoicated target process > + * @start: start of the region to mark for exclusive device access > + * @end: end address o

RE: [PATCH v3 5/8] mm: Device exclusive memory access

2021-03-01 Thread Ralph Campbell
> From: Alistair Popple > Sent: Thursday, February 25, 2021 11:18 PM > To: linux...@kvack.org; nouv...@lists.freedesktop.org; > bske...@redhat.com; a...@linux-foundation.org > Cc: linux-...@vger.kernel.org; linux-kernel@vger.kernel.org; dri- > de...@lists.freedesktop.org; John Hubbard ; Ralph > Ca

Re: [PATCH v3 5/8] mm: Device exclusive memory access

2021-03-01 Thread Jason Gunthorpe
On Fri, Feb 26, 2021 at 06:18:29PM +1100, Alistair Popple wrote: > Some devices require exclusive write access to shared virtual > memory (SVM) ranges to perform atomic operations on that memory. This > requires CPU page tables to be updated to deny access whilst atomic > operations are occurring.