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

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Message-Id: <20080211093433.DE4961B41CE@basil.firstfloor.org>
Date:	Mon, 11 Feb 2008 10:34:33 +0100 (CET)
From:	Andi Kleen <ak@...e.de>
To:	tglx@...utronix.de, mingo@...e.hu, linux-kernel@...r.kernel.org
Subject: [PATCH] [5/8] Fix logic error in 64bit memory hotadd


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@...e.de>

---
 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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