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authorAndrey Ryabinin <aryabinin@virtuozzo.com>2018-06-25 13:24:27 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-07-08 15:32:21 +0200
commitb77816b86b957e61560a5829deea0dca993b078a (patch)
parent54fb3c180d05e9dfda892a93413514e99f0cbb19 (diff)
x86/mm: Don't free P4D table when it is folded at runtime
commit 0e311d237d7f3022b7dafb639b42541bfb42fe94 upstream. When the P4D page table layer is folded at runtime, the p4d_free() should do nothing, the same as in <asm-generic/pgtable-nop4d.h>. It seems this bug should cause double-free in efi_call_phys_epilog(), but I don't know how to trigger that code path, so I can't confirm that by testing. Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org # 4.17 Fixes: 98219dda2ab5 ("x86/mm: Fold p4d page table layer at runtime") Link: http://lkml.kernel.org/r/20180625102427.15015-1-aryabinin@virtuozzo.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index 263c142a6a6c..f65e9e1cea4c 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -184,6 +184,9 @@ static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr)
static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
+ if (!pgtable_l5_enabled)
+ return;
BUG_ON((unsigned long)p4d & (PAGE_SIZE-1));
free_page((unsigned long)p4d);