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Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap for unaddressable

From Jerome Glisse <jglisse@redhat.com>
Newsgroups linux.kernel
Subject Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap for unaddressable
Date 2016-11-21 13:50 +0100
Message-ID <sFWcN-1f8-5@gated-at.bofh.it> (permalink)
References <sEUZr-1B7-3@gated-at.bofh.it> <sEV98-1Es-35@gated-at.bofh.it> <sFUul-7g-7@gated-at.bofh.it>
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On Mon, Nov 21, 2016 at 04:28:04PM +0530, Anshuman Khandual wrote:
> On 11/18/2016 11:48 PM, Jérôme Glisse wrote:
> > To allow use of device un-addressable memory inside a process add a
> > special swap type. Also add a new callback to handle page fault on
> > such entry.
> 
> IIUC this swap type is required only for the mirror cases and its
> not a requirement for migration. If it's required for mirroring
> purpose where we intercept each page fault, the commit message
> here should clearly elaborate on that more.

It is only require for un-addressable memory. The mirroring has nothing to do
with it. I will clarify commit message.

[...]

> > diff --git a/include/linux/memremap.h b/include/linux/memremap.h
> > index b6f03e9..d584c74 100644
> > --- a/include/linux/memremap.h
> > +++ b/include/linux/memremap.h
> > @@ -47,6 +47,11 @@ static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
> >   */
> >  struct dev_pagemap {
> >  	void (*free_devpage)(struct page *page, void *data);
> > +	int (*fault)(struct vm_area_struct *vma,
> > +		     unsigned long addr,
> > +		     struct page *page,
> > +		     unsigned flags,
> > +		     pmd_t *pmdp);
> 
> We are extending the dev_pagemap once again to accommodate device driver
> specific fault routines for these pages. Wondering if this extension and
> the new swap type should be in the same patch.

It make sense to have it in one single patch as i also change page fault code
path to deal with the new special swap entry and those make use of this new
callback.


> > +int device_entry_fault(struct vm_area_struct *vma,
> > +		       unsigned long addr,
> > +		       swp_entry_t entry,
> > +		       unsigned flags,
> > +		       pmd_t *pmdp)
> > +{
> > +	struct page *page = device_entry_to_page(entry);
> > +
> 
> A BUG_ON() if page->pgmap->fault has not been populated by the driver.
> 

Ok

Cheers,
Jérôme

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Thread

[HMM v13 00/18] HMM (Heterogeneous Memory Management) v13 Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:20 +0100
  [HMM v13 13/18] mm/hmm/mirror: device page fault handler Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:20 +0100
  [HMM v13 12/18] mm/hmm/mirror: helper to snapshot CPU page table Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:30 +0100
  [HMM v13 02/18] mm/ZONE_DEVICE/unaddressable: add support for un-addressable device memory Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:30 +0100
    Re: [HMM v13 02/18] mm/ZONE_DEVICE/unaddressable: add support for  un-addressable device memory Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-21 09:10 +0100
      Re: [HMM v13 02/18] mm/ZONE_DEVICE/unaddressable: add support for  un-addressable device memory Jerome Glisse <jglisse@redhat.com> - 2016-11-21 13:40 +0100
        Re: [HMM v13 02/18] mm/ZONE_DEVICE/unaddressable: add support for  un-addressable device memory Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-22 06:20 +0100
  [HMM v13 09/18] mm/hmm/mirror: mirror process address space on device with HMM helpers Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:30 +0100
    Re: [HMM v13 09/18] mm/hmm/mirror: mirror process address space on  device with HMM helpers Balbir Singh <bsingharora@gmail.com> - 2016-11-21 03:50 +0100
      Re: [HMM v13 09/18] mm/hmm/mirror: mirror process address space on  device with HMM helpers Jerome Glisse <jglisse@redhat.com> - 2016-11-21 06:20 +0100
  [HMM v13 05/18] mm/ZONE_DEVICE/devmem_pages_remove: allow early removal of device memory Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:30 +0100
    Re: [HMM v13 05/18] mm/ZONE_DEVICE/devmem_pages_remove: allow early  removal of device memory Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-21 11:40 +0100
      Re: [HMM v13 05/18] mm/ZONE_DEVICE/devmem_pages_remove: allow early  removal of device memory Jerome Glisse <jglisse@redhat.com> - 2016-11-21 13:40 +0100
        Re: [HMM v13 05/18] mm/ZONE_DEVICE/devmem_pages_remove: allow early  removal of device memory Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-22 06:00 +0100
  [HMM v13 04/18] mm/ZONE_DEVICE/free-page: callback when page is freed Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:30 +0100
    Re: [HMM v13 04/18] mm/ZONE_DEVICE/free-page: callback when page is  freed Balbir Singh <bsingharora@gmail.com> - 2016-11-21 03:00 +0100
      Re: [HMM v13 04/18] mm/ZONE_DEVICE/free-page: callback when page is  freed Jerome Glisse <jglisse@redhat.com> - 2016-11-21 06:00 +0100
    Re: [HMM v13 04/18] mm/ZONE_DEVICE/free-page: callback when page is  freed Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-21 09:30 +0100
      Re: [HMM v13 04/18] mm/ZONE_DEVICE/free-page: callback when page is  freed Jerome Glisse <jglisse@redhat.com> - 2016-11-21 13:40 +0100
        Re: [HMM v13 04/18] mm/ZONE_DEVICE/free-page: callback when page is  freed Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-22 06:10 +0100
  [HMM v13 10/18] mm/hmm/mirror: add range lock helper, prevent CPU page table update for the range Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:30 +0100
  [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap for unaddressable Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:30 +0100
    Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap  for unaddressable Balbir Singh <bsingharora@gmail.com> - 2016-11-21 03:10 +0100
      Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap  for unaddressable Jerome Glisse <jglisse@redhat.com> - 2016-11-21 06:10 +0100
        Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap  for unaddressable Balbir Singh <bsingharora@gmail.com> - 2016-11-22 03:30 +0100
          Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap  for unaddressable Jerome Glisse <jglisse@redhat.com> - 2016-11-22 15:00 +0100
      Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap  for unaddressable Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-21 12:20 +0100
    Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap  for unaddressable Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-21 12:00 +0100
      Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap  for unaddressable Jerome Glisse <jglisse@redhat.com> - 2016-11-21 13:50 +0100
        Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap  for unaddressable Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-22 05:50 +0100
          Re: [HMM v13 06/18] mm/ZONE_DEVICE/unaddressable: add special swap  for unaddressable Jerome Glisse <jglisse@redhat.com> - 2016-11-24 15:00 +0100
  [HMM v13 11/18] mm/hmm/mirror: add range monitor helper, to monitor CPU page table update Jérôme Glisse <jglisse@redhat.com> - 2016-11-18 18:30 +0100
  Re: [HMM v13 00/18] HMM (Heterogeneous Memory Management) v13 John Hubbard <jhubbard@nvidia.com> - 2016-11-19 01:50 +0100
    Re: [HMM v13 00/18] HMM (Heterogeneous Memory Management) v13 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2016-11-19 16:00 +0100

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