[PATCH] [5/8] Fix logic error in 64bit memory hotadd

[Andi Kleen]

The memory hotadd code assumes that the pud always exists already, but 
that might be not true. Allocate it if it isn't there.

Signed-off-by: Andi Kleen <ak@xxxxxxx>

---
 arch/x86/mm/init_64.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

Index: linux/arch/x86/mm/init_64.c
===================================================================
--- linux.orig/arch/x86/mm/init_64.c
+++ linux/arch/x86/mm/init_64.c
@@ -432,17 +432,22 @@ void __init_refok init_memory_mapping(un
 		unsigned long pud_phys;
 		pud_t *pud;
 
-		if (after_bootmem)
+		if (after_bootmem) {
 			pud = pud_offset(pgd, start & PGDIR_MASK);
-		else
+			if (!pud_present(*pud)) {
+				pud = (pud_t *)get_zeroed_page(GFP_ATOMIC);
+				if (!pud)
+					panic("Out of memory");
+			}
+			pud_phys = __pa(pud);
+		} else
 			pud = alloc_low_page(&pud_phys);
 
 		next = start + PGDIR_SIZE;
 		if (next > end)
 			next = end;
 		phys_pud_init(pud, __pa(start), __pa(next));
-		if (!after_bootmem)
-			set_pgd(pgd_offset_k(start), mk_kernel_pgd(pud_phys));
+		set_pgd(pgd_offset_k(start), mk_kernel_pgd(pud_phys));
 		unmap_low_page(pud);
 	}
 
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