Commit-ID: 0e311d237d7f3022b7dafb639b42541bfb42fe94 Gitweb: https://git.kernel.org/tip/0e311d237d7f3022b7dafb639b42541bfb42fe94 Author: Andrey Ryabinin <[email protected]> AuthorDate: Mon, 25 Jun 2018 13:24:27 +0300 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 26 Jun 2018 09:21:48 +0200
x86/mm: Don't free P4D table when it is folded at runtime 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 <[email protected]> Reviewed-by: Kirill A. Shutemov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] # 4.17 Fixes: 98219dda2ab5 ("x86/mm: Fold p4d page table layer at runtime") Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/include/asm/pgalloc.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h index ada6410fd2ec..fbd578daa66e 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); }
