x86: do not PSE on CONFIG_DEBUG_PAGEALLOC=y

get more testing of the c_p_a() code done by not turning off
PSE on DEBUG_PAGEALLOC.

this simplifies the early pagetable setup code, and tests
the largepage-splitup code quite heavily.

In the end, all the largepages will be split up pretty quickly,
so there's no difference to how DEBUG_PAGEALLOC worked before.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 11 insertions, 8 deletions

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index bba850b05d0e..db28aa9e2f69 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -641,13 +641,6 @@ void __init early_cpu_init(void)
         nexgen_init_cpu();
         umc_init_cpu();
         early_cpu_detect();
-
-#ifdef CONFIG_DEBUG_PAGEALLOC
-        /* pse is not compatible with on-the-fly unmapping,
-         * disable it even if the cpus claim to support it.
-         */
-        setup_clear_cpu_cap(X86_FEATURE_PSE);
-#endif
 }
 
 /* Make sure %fs is initialized properly in idle threads */
diff --git a/arch/x86/mm/pageattr_32.c b/arch/x86/mm/pageattr_32.c
index 9cf2fea54eb5..dd49b16b3a0e 100644
--- a/arch/x86/mm/pageattr_32.c
+++ b/arch/x86/mm/pageattr_32.c
@@ -61,13 +61,17 @@ static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
 static int split_large_page(pte_t *kpte, unsigned long address)
 {
         pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
+        gfp_t gfp_flags = GFP_KERNEL;
         unsigned long flags;
         unsigned long addr;
         pte_t *pbase, *tmp;
         struct page *base;
         int i, level;
 
-        base = alloc_pages(GFP_KERNEL, 0);
+#ifdef CONFIG_DEBUG_PAGEALLOC
+        gfp_flags = GFP_ATOMIC;
+#endif
+        base = alloc_pages(gfp_flags, 0);
         if (!base)
                 return -ENOMEM;
 
@@ -219,6 +223,12 @@ void kernel_map_pages(struct page *page, int numpages, int enable)
         }
 
         /*
+         * If page allocator is not up yet then do not call c_p_a():
+         */
+        if (!debug_pagealloc_enabled)
+                return;
+
+        /*
          * the return value is ignored - the calls cannot fail,
          * large pages are disabled at boot time.
          */