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Subject[PATCH tip:x86/urgent] x86-32, NUMA: Fix boot regression caused by NUMA init unification on highmem machines
During 32/64 NUMA init unification, commit 797390d855 "x86-32, NUMA:
use sparse_memory_present_with_active_regions()" made 32bit mm init
call memory_present() automatically from active_regions instead of
leaving it to each NUMA init path.

This commit description is inaccurate - memory_present() calls aren't
the same for flat and numaq. After the commit, memory_present() is
only called for the intersection of e820 and NUMA layout. Before, on
flatmem, memory_present() would be called from 0 to max_pfn. After,
it would be called only on the areas that e820 indicates to be

This is how x86_64 works and should be okay as memmap is allowed to
contain holes; however, x86_32 DISCONTIGMEM is missing
early_pfn_valid(), which makes memmap_init_zone() assume that memmap
doesn't contain any hole. This leads to the following oops if e820
map contains holes as it often does on machine with near or more 4GiB
of memory by calling pfn_to_page() on a pfn which isn't mapped to a
NUMA node.

BUG: unable to handle kernel paging request at 000012b0
IP: [<c1aa13ce>] memmap_init_zone+0x6c/0xf2
*pdpt =3D 0000000000000000 *pde =3D f000eef3f000ee00
Oops: 0000 [#1] SMP
last sysfs file:
Modules linked in:
Pid: 0, comm: swapper Not tainted 2.6.39-rc5-00164-g797390d #1 To Be Filled By O.E.M. To Be Filled By O.E.M./E350M1
EIP: 0060:[<c1aa13ce>] EFLAGS: 00010012 CPU: 0
EIP is at memmap_init_zone+0x6c/0xf2
EAX: 00000000 EBX: 000a8000 ECX: 000a7fff EDX: f2c00b80
ESI: 000a8000 EDI: f2c00800 EBP: c19ffe54 ESP: c19ffe34
DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
Process swapper (pid: 0, ti=3Dc19fe000 task=3Dc1a07f60 task.ti=3Dc19fe000)
00000002 00000000 0023f000 00000000 10000000 00000a00 f2c00000 f2c00b58
c19ffeb0 c1a80f24 000375fe 00000000 f2c00800 00000800 00000100 00000030
c1abb768 0000003c 00000000 00000000 00000004 00207a02 f2c00800 000375fe
Call Trace:
[<c1a80f24>] free_area_init_node+0x358/0x385
[<c1a81384>] free_area_init_nodes+0x420/0x487
[<c1a79326>] paging_init+0x114/0x11b
[<c1a6cb13>] setup_arch+0xb37/0xc0a
[<c1a69554>] start_kernel+0x76/0x316
[<c1a690a8>] i386_start_kernel+0xa8/0xb0
This patch fixes the bug by defining early_pfn_valid() to be the same
as pfn_valid() when DISCONTIGMEM.

Signed-off-by: Tejun Heo <>
Reported-and-bisected-by: Conny Seidel <>
LKML-Reference: <>
Conny, can you please verify this fixes the boot problem you're

arch/x86/include/asm/mmzone_32.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/include/asm/mmzone_32.h b/arch/x86/include/asm/mmzone_32.h
index 5e83a41..756d2a7 100644
--- a/arch/x86/include/asm/mmzone_32.h
+++ b/arch/x86/include/asm/mmzone_32.h
@@ -68,6 +68,8 @@ static inline int pfn_valid(int pfn)
return 0;

+#define early_pfn_valid(pfn) pfn_valid((pfn))


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