x86/ldt: Remove unused variable in map_ldt_struct()

Splitting out the sanity check in map_ldt_struct() moved page table syncing
into a separate function, which made the pgd variable unused. Remove it.

[ tglx: Massaged changelog ]

Fixes: 9bae3197e1 ("x86/ldt: Split out sanity check in map_ldt_struct()")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: bp@alien8.de
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: peterz@infradead.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: bhe@redhat.com
Cc: willy@infradead.org
Cc: linux-mm@kvack.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181026122856.66224-4-kirill.shutemov@linux.intel.com

arch/x86/kernel/ldt.c

@@ -207,7 +207,6 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
 	bool is_vmalloc;
 	spinlock_t *ptl;
 	int i, nr_pages;
-	pgd_t *pgd;
 
 	if (!static_cpu_has(X86_FEATURE_PTI))
 		return 0;
@@ -221,13 +220,6 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
 	/* Check if the current mappings are sane */
 	sanity_check_ldt_mapping(mm);
 
-	/*
-	 * Did we already have the top level entry allocated?  We can't
-	 * use pgd_none() for this because it doens't do anything on
-	 * 4-level page table kernels.
-	 */
-	pgd = pgd_offset(mm, LDT_BASE_ADDR);
-
 	is_vmalloc = is_vmalloc_addr(ldt->entries);
 
 	nr_pages = DIV_ROUND_UP(ldt->nr_entries * LDT_ENTRY_SIZE, PAGE_SIZE);