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Re: [v6 11/15] arm64/kasan: explicitly zero kasan shadow memory

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On Tue, Aug 08, 2017 at 07:49:22AM -0400, Pasha Tatashin wrote:
> Hi Will,
> 
> Thank you for looking at this change. What you described was in my previous
> iterations of this project.
> 
> See for example here: https://lkml.org/lkml/2017/5/5/369
> 
> I was asked to remove that flag, and only zero memory in place when needed.
> Overall the current approach is better everywhere else in the kernel, but it
> adds a little extra code to kasan initialization.

Damn, I actually prefer the flag :)

But actually, if you look at our implementation of vmemmap_populate, then we
have our own version of vmemmap_populate_basepages that terminates at the
pmd level anyway if ARM64_SWAPPER_USES_SECTION_MAPS. If there's resistance
to do this in the core code, then I'd be inclined to replace our
vmemmap_populate implementation in the arm64 code with a single version that
can terminate at either the PMD or the PTE level, and do zeroing if
required. We're already special-casing it, so we don't really lose anything
imo.

Will

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[v6 00/15] complete deferred page initialization Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-08-07 22:50 +0200
  [v6 09/15] sparc64: optimized struct page zeroing Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-08-07 22:50 +0200
    Re: [v6 09/15] sparc64: optimized struct page zeroing Michal Hocko <mhocko@kernel.org> - 2017-08-11 15:00 +0200
      Re: [v6 09/15] sparc64: optimized struct page zeroing Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-11 18:10 +0200
  [v6 08/15] mm: zero struct pages during initialization Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-08-07 22:50 +0200
    Re: [v6 08/15] mm: zero struct pages during initialization Michal Hocko <mhocko@kernel.org> - 2017-08-11 15:00 +0200
      Re: [v6 08/15] mm: zero struct pages during initialization Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-11 18:10 +0200
  [v6 07/15] mm: defining memblock_virt_alloc_try_nid_raw Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-08-07 22:50 +0200
    Re: [v6 07/15] mm: defining memblock_virt_alloc_try_nid_raw Michal Hocko <mhocko@kernel.org> - 2017-08-11 14:50 +0200
      Re: [v6 07/15] mm: defining memblock_virt_alloc_try_nid_raw Michal Hocko <mhocko@kernel.org> - 2017-08-11 18:10 +0200
        Re: [v6 07/15] mm: defining memblock_virt_alloc_try_nid_raw Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-11 18:30 +0200
      Re: [v6 07/15] mm: defining memblock_virt_alloc_try_nid_raw Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-11 18:10 +0200
  [v6 10/15] x86/kasan: explicitly zero kasan shadow memory Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-08-07 22:50 +0200
  [v6 05/15] mm: don't accessed uninitialized struct pages Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-08-07 22:50 +0200
    Re: [v6 05/15] mm: don't accessed uninitialized struct pages Michal Hocko <mhocko@kernel.org> - 2017-08-11 11:40 +0200
      Re: [v6 05/15] mm: don't accessed uninitialized struct pages Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-11 18:00 +0200
  [v6 11/15] arm64/kasan: explicitly zero kasan shadow memory Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-08-07 22:50 +0200
    Re: [v6 11/15] arm64/kasan: explicitly zero kasan shadow memory Will Deacon <will.deacon@arm.com> - 2017-08-08 11:10 +0200
      Re: [v6 11/15] arm64/kasan: explicitly zero kasan shadow memory Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-08 14:00 +0200
        Re: [v6 11/15] arm64/kasan: explicitly zero kasan shadow memory Will Deacon <will.deacon@arm.com> - 2017-08-08 14:40 +0200
          Re: [v6 11/15] arm64/kasan: explicitly zero kasan shadow memory Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-08 15:00 +0200
        RE: [v6 11/15] arm64/kasan: explicitly zero kasan shadow memory David Laight <David.Laight@ACULAB.COM> - 2017-08-08 15:20 +0200
          Re: [v6 11/15] arm64/kasan: explicitly zero kasan shadow memory Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-08 15:40 +0200
  [v6 13/15] mm: stop zeroing memory during allocation in vmemmap Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-08-07 22:50 +0200
    Re: [v6 13/15] mm: stop zeroing memory during allocation in vmemmap Michal Hocko <mhocko@kernel.org> - 2017-08-11 15:10 +0200
      Re: [v6 13/15] mm: stop zeroing memory during allocation in vmemmap Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-11 18:20 +0200
  Re: [v6 00/15] complete deferred page initialization Michal Hocko <mhocko@kernel.org> - 2017-08-11 10:00 +0200
    Re: [v6 00/15] complete deferred page initialization Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-08-11 17:20 +0200
      Re: [v6 00/15] complete deferred page initialization Michal Hocko <mhocko@kernel.org> - 2017-08-11 17:30 +0200

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