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| author |   Andrey Ryabinin <aryabinin@virtuozzo.com> | 2018-06-25 13:24:27 +0300 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2018-06-26 09:21:48 +0200 |
| commit | 0e311d237d7f3022b7dafb639b42541bfb42fe94 (patch) | |
| tree | e85cd99eb616208781f58e1f9034f3d752f60639 /arch | |
| parent | x86/entry/32: Add explicit 'l' instruction suffix (diff) | |
| download | linux-dev-0e311d237d7f3022b7dafb639b42541bfb42fe94.tar.xz linux-dev-0e311d237d7f3022b7dafb639b42541bfb42fe94.zip | |
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 <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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/pgalloc.h | 3 |
1 files changed, 3 insertions, 0 deletions
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); } |