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| author |   David Vrabel <david.vrabel@citrix.com> | 2015-02-19 13:06:53 +0000 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-19 15:04:49 -0800 |
| commit | e3a1f6cac1fe20e7ac01d96c914c25726723a64e (patch) | |
| tree | b0041715d2f98db2dda0e01e880385212a4723b4 | |
| parent | Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs (diff) | |
| download | linux-dev-e3a1f6cac1fe20e7ac01d96c914c25726723a64e.tar.xz linux-dev-e3a1f6cac1fe20e7ac01d96c914c25726723a64e.zip | |
x86: pte_protnone() and pmd_protnone() must check entry is not present
Since _PAGE_PROTNONE aliases _PAGE_GLOBAL it is only valid if
_PAGE_PRESENT is clear. Make pte_protnone() and pmd_protnone() check
for this.
This fixes a 64-bit Xen PV guest regression introduced by 8a0516ed8b90
("mm: convert p[te|md]_numa users to p[te|md]_protnone_numa"). Any
userspace process would endlessly fault.
In a 64-bit PV guest, userspace page table entries have _PAGE_GLOBAL set
by the hypervisor. This meant that any fault on a present userspace
entry (e.g., a write to a read-only mapping) would be misinterpreted as
a NUMA hinting fault and the fault would not be correctly handled,
resulting in the access endlessly faulting.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | arch/x86/include/asm/pgtable.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 67fc3d2b0aab..a0c35bf6cb92 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -476,12 +476,14 @@ static inline int pmd_present(pmd_t pmd) */ static inline int pte_protnone(pte_t pte) { - return pte_flags(pte) & _PAGE_PROTNONE; + return (pte_flags(pte) & (_PAGE_PROTNONE | _PAGE_PRESENT)) + == _PAGE_PROTNONE; } static inline int pmd_protnone(pmd_t pmd) { - return pmd_flags(pmd) & _PAGE_PROTNONE; + return (pmd_flags(pmd) & (_PAGE_PROTNONE | _PAGE_PRESENT)) + == _PAGE_PROTNONE; } #endif /* CONFIG_NUMA_BALANCING */ |