3 files changed, 38 insertions, 5 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e7848a0d99eb..e2c74872ab70 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2703,6 +2703,13 @@ and is between 256 and 4096 characters. It is defined in the file
                                         medium is write-protected).
                         Example: quirks=0419:aaf5:rl,0421:0433:rc
 
+        userpte=
+                        [X86] Flags controlling user PTE allocations.
+
+                                nohigh = do not allocate PTE pages in
+                                        HIGHMEM regardless of setting
+                                        of CONFIG_HIGHPTE.
+
         vdso=           [X86,SH]
                         vdso=2: enable compat VDSO (default with COMPAT_VDSO)
                         vdso=1: enable VDSO (default)
diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index 0e8c2a0fd922..271de94c3810 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -23,6 +23,11 @@ static inline void paravirt_release_pud(unsigned long pfn) {}
 #endif
 
 /*
+ * Flags to use when allocating a user page table page.
+ */
+extern gfp_t __userpte_alloc_gfp;
+
+/*
  * Allocate and free page tables.
  */
 extern pgd_t *pgd_alloc(struct mm_struct *);
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index ed34f5e35999..c9ba9deafe83 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -6,6 +6,14 @@
 
 #define PGALLOC_GFP GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO
 
+#ifdef CONFIG_HIGHPTE
+#define PGALLOC_USER_GFP __GFP_HIGHMEM
+#else
+#define PGALLOC_USER_GFP 0
+#endif
+
+gfp_t __userpte_alloc_gfp = PGALLOC_GFP | PGALLOC_USER_GFP;
+
 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 {
         return (pte_t *)__get_free_page(PGALLOC_GFP);
@@ -15,16 +23,29 @@ pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
 {
         struct page *pte;
 
-#ifdef CONFIG_HIGHPTE
-        pte = alloc_pages(PGALLOC_GFP | __GFP_HIGHMEM, 0);
-#else
-        pte = alloc_pages(PGALLOC_GFP, 0);
-#endif
+        pte = alloc_pages(__userpte_alloc_gfp, 0);
         if (pte)
                 pgtable_page_ctor(pte);
         return pte;
 }
 
+static int __init setup_userpte(char *arg)
+{
+        if (!arg)
+                return -EINVAL;
+
+        /*
+         * "userpte=nohigh" disables allocation of user pagetables in
+         * high memory.
+         */
+        if (strcmp(arg, "nohigh") == 0)
+                __userpte_alloc_gfp &= ~__GFP_HIGHMEM;
+        else
+                return -EINVAL;
+        return 0;
+}
+early_param("userpte", setup_userpte);
+
 void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
 {
         pgtable_page_dtor(pte);