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[Chris Valean <cvalean@xxxxxxxxxxxxxxxxxxxxxx>]

** Changed in: linux (Ubuntu)
       Status: Incomplete => Confirmed

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https://bugs.launchpad.net/bugs/1549601

Title:
  [Hyper-V] x86,pageattr: prevent overflow in slow_virt_to_phys() for
  X86_PAE

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d1cd1210834649ce1ca6bafe5ac25d2f40331343

  x86, pageattr: Prevent overflow in slow_virt_to_phys() for X86_PAE
  pte_pfn() returns a PFN of long (32 bits in 32-PAE), so "long <<
  PAGE_SHIFT" will overflow for PFNs above 4GB.

  Due to this issue, some Linux 32-PAE distros, running as guests on Hyper-V,
  with 5GB memory assigned, can't load the netvsc driver successfully and
  hence the synthetic network device can't work (we can use the kernel parameter
  mem=3000M to work around the issue).

  Cast pte_pfn() to phys_addr_t before shifting.

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