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Re: [RFC V2 12/12] mm: Tag VMA with VM_CDM flag explicitly during mbind(MPOL_BIND)

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On 01/30/2017 11:24 PM, Dave Hansen wrote:
> On 01/29/2017 07:35 PM, Anshuman Khandual wrote:
>> +		if ((new_pol->mode == MPOL_BIND)
>> +			&& nodemask_has_cdm(new_pol->v.nodes))
>> +			set_vm_cdm(vma);
> So, if you did:
> 
> 	mbind(addr, PAGE_SIZE, MPOL_BIND, all_nodes, ...);
> 	mbind(addr, PAGE_SIZE, MPOL_BIND, one_non_cdm_node, ...);
> 
> You end up with a VMA that can never have KSM done on it, etc...  Even
> though there's no good reason for it.  I guess /proc/$pid/smaps might be
> able to help us figure out what was going on here, but that still seems
> like an awful lot of damage.

Agreed, this VMA should not remain tagged after the second call. It does
not make sense. For this kind of scenarios we can re-evaluate the VMA
tag every time the nodemask change is attempted. But if we are looking for
some runtime re-evaluation then we need to steal some cycles are during
general VMA processing opportunity points like merging and split to do
the necessary re-evaluation. Should do we do these kind two kinds of
re-evaluation to be more optimal ?

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[RFC V2 00/12] Define coherent device memory node Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:40 +0100
  [RFC V2 05/12] cpuset: Add cpuset_inc() inside cpuset_init() Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:40 +0100
    Re: [RFC V2 05/12] cpuset: Add cpuset_inc() inside cpuset_init() Dave Hansen <dave.hansen@intel.com> - 2017-01-30 19:20 +0100
    Re: [RFC V2 05/12] cpuset: Add cpuset_inc() inside cpuset_init() Mel Gorman <mgorman@suse.de> - 2017-01-30 21:50 +0100
      [RFC] cpuset: Enable changing of top_cpuset's mems_allowed nodemask Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-31 15:30 +0100
        Re: [RFC] cpuset: Enable changing of top_cpuset's mems_allowed  nodemask Mel Gorman <mgorman@suse.de> - 2017-01-31 17:10 +0100
          Re: [RFC] cpuset: Enable changing of top_cpuset's mems_allowed  nodemask Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-02-01 08:40 +0100
            Re: [RFC] cpuset: Enable changing of top_cpuset's mems_allowed  nodemask Michal Hocko <mhocko@kernel.org> - 2017-02-01 10:00 +0100
            Re: [RFC] cpuset: Enable changing of top_cpuset's mems_allowed  nodemask Mel Gorman <mgorman@suse.de> - 2017-02-01 10:20 +0100
      Re: [RFC V2 05/12] cpuset: Add cpuset_inc() inside cpuset_init() Vlastimil Babka <vbabka@suse.cz> - 2017-01-31 15:40 +0100
        Re: [RFC V2 05/12] cpuset: Add cpuset_inc() inside cpuset_init() Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-31 16:40 +0100
  [RFC V2 04/12] mm: Change mbind(MPOL_BIND) implementation for CDM nodes Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:40 +0100
  [DEBUG 16/21] mm: Enable CONFIG_MOVABLE_NODE on powerpc Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:50 +0100
  [DEBUG 18/21] mm: Add debugfs interface to dump each node's zonelist information Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:50 +0100
  [DEBUG 19/21] mm: Add migrate_virtual_range migration interface Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:50 +0100
  [DEBUG 17/21] mm: Export definition of 'zone_names' array through mmzone.h Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:50 +0100
  [DEBUG 15/21] powerpc/mm: Enable CONFIG_MOVABLE_NODE for PPC64 platform Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:50 +0100
  [DEBUG 21/21] selftests/powerpc: Add a script to perform random VMA migrations Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:50 +0100
  [DEBUG 14/21] powerpc/mm: Create numa nodes for hotplug memory Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:50 +0100
  [DEBUG 13/21] powerpc/mm: Identify coherent device memory nodes during platform init Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:50 +0100
  [DEBUG 20/21] drivers: Add two drivers for coherent device memory tests Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 04:50 +0100
  [RFC V2 09/12] mm: Exclude CDM marked VMAs from auto NUMA Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 07:10 +0100
  [RFC V2 12/12] mm: Tag VMA with VM_CDM flag explicitly during mbind(MPOL_BIND) Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 07:20 +0100
    Re: [RFC V2 12/12] mm: Tag VMA with VM_CDM flag explicitly during  mbind(MPOL_BIND) Dave Hansen <dave.hansen@intel.com> - 2017-01-30 19:00 +0100
      Re: [RFC V2 12/12] mm: Tag VMA with VM_CDM flag explicitly during  mbind(MPOL_BIND) Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-31 05:40 +0100
        Re: [RFC V2 12/12] mm: Tag VMA with VM_CDM flag explicitly during  mbind(MPOL_BIND) Dave Hansen <dave.hansen@intel.com> - 2017-02-07 19:10 +0100
          Re: [RFC V2 12/12] mm: Tag VMA with VM_CDM flag explicitly during  mbind(MPOL_BIND) Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-02-08 17:50 +0100
          Re: [RFC V2 12/12] mm: Tag VMA with VM_CDM flag explicitly during  mbind(MPOL_BIND) Jerome Glisse <jglisse@redhat.com> - 2017-02-08 19:40 +0100
  [RFC V2 10/12] mm: Ignore madvise(MADV_MERGEABLE) request for VM_CDM marked VMAs Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 10:30 +0100
  [RFC V2 11/12] mm: Tag VMA with VM_CDM flag during page fault Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-30 10:40 +0100
    Re: [RFC V2 11/12] mm: Tag VMA with VM_CDM flag during page fault Dave Hansen <dave.hansen@intel.com> - 2017-01-30 19:00 +0100
      Re: [RFC V2 11/12] mm: Tag VMA with VM_CDM flag during page fault Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-31 06:20 +0100
        Re: [RFC V2 11/12] mm: Tag VMA with VM_CDM flag during page fault Dave Hansen <dave.hansen@intel.com> - 2017-01-31 19:10 +0100
  Re: [RFC V2 00/12] Define coherent device memory node Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-01-31 06:50 +0100
    Re: [RFC V2 00/12] Define coherent device memory node Jerome Glisse <jglisse@redhat.com> - 2017-01-31 07:20 +0100

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