[GIT PULL] arm64: Fix for -rc7

[Will Deacon]

Hi Linus,

Please pull this single arm64 fix for -rc7. It's a revert of 747a70e60b72
("arm64: Fix copy-on-write referencing in HugeTLB"), not because that
patch was wrong, but because it was broken by aa57157be69f ("arm64: Ensure
VM_WRITE|VM_SHARED ptes are clean by default") which we merged in -rc6.

We spotted the issue in Android (AOSP), where one of the JIT threads gets
stuck on a write fault during boot because the faulting pte is marked as
PTE_DIRTY | PTE_WRITE | PTE_RDONLY and the fault handler decides that
there's nothing to do thanks to pte_same() masking out PTE_RDONLY.

Thanks to John Stultz for reporting this and testing this so quickly, and
to Steve Capper for confirming that the HugeTLB tests continue to pass.

Cheers,

Will

--->8

The following changes since commit 1cf45b8fdbb87040e1d1bd793891089f4678aa41:

  arm64: apply ARM64_ERRATUM_843419 workaround for Brahma-B53 core (2019-11-01 10:47:37 +0000)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git tags/arm64-fixes

for you to fetch changes up to 6767df245f4736d0cf0c6fb7cf9cf94b27414245:

  arm64: Do not mask out PTE_RDONLY in pte_same() (2019-11-06 19:31:56 +0000)

----------------------------------------------------------------
arm64 fix for -rc7

- Fix pte_same() to avoid getting stuck on write fault

----------------------------------------------------------------
Catalin Marinas (1):
      arm64: Do not mask out PTE_RDONLY in pte_same()

 arch/arm64/include/asm/pgtable.h | 17 -----------------
 1 file changed, 17 deletions(-)