[PATCH x86/mm] x86-64, NUMA: Don't assume phys node 0 is alwaysonline in numa_emulation() handling

From: Tejun Heo
Date: Fri Mar 04 2011 - 10:37:13 EST


Undetermined entries in emu_nid_to_phys[] are filled with zero
assuming that physical node 0 is always online; however, this might
not be true depending on hardware configuration. Find a physical node
which is actually online and use it instead.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Reported-by: David Rientjes <rientjes@xxxxxxxxxx>
LKML-Reference: <alpine.DEB.2.00.1103020628210.31626@xxxxxxxxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/numa_emulation.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index 75b31dc..3696be0 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -301,6 +301,7 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
const u64 max_addr = max_pfn << PAGE_SHIFT;
u8 *phys_dist = NULL;
size_t phys_size = numa_dist_cnt * numa_dist_cnt * sizeof(phys_dist[0]);
+ int dfl_phys_nid;
int i, j, ret;

if (!emu_cmdline)
@@ -357,6 +358,19 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
node_distance(i, j);
}

+ /* determine the default phys nid to use for unmapped nodes */
+ dfl_phys_nid = NUMA_NO_NODE;
+ for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
+ if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
+ dfl_phys_nid = emu_nid_to_phys[i];
+ break;
+ }
+ }
+ if (dfl_phys_nid == NUMA_NO_NODE) {
+ pr_warning("NUMA: Warning: can't determine default physical node, disabling emulation\n");
+ goto no_emu;
+ }
+
/* commit */
*numa_meminfo = ei;

@@ -377,7 +391,7 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
/* make sure all emulated nodes are mapped to a physical node */
for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++)
if (emu_nid_to_phys[i] == NUMA_NO_NODE)
- emu_nid_to_phys[i] = 0;
+ emu_nid_to_phys[i] = dfl_phys_nid;

/*
* Transform distance table. numa_set_distance() ignores all
--
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