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Subject[PATCH] percpu: fix unit_map[] verification in pcpu_setup_first_chunk()
pcpu_setup_first_chunk() incorrectly used NR_CPUS as the impossible
unit number while unit number can equal and go over NR_CPUS with
sparse unit map. This triggers BUG_ON() spuriously on machines which
have non-power-of-two number of cpus. Use UINT_MAX instead.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Tony Vroon <tony@linx.net>
---
Erghh... stupid mistake. This should fix it. Can you please verify?

Thanks.

mm/percpu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

Index: work/mm/percpu.c
===================================================================
--- work.orig/mm/percpu.c
+++ work/mm/percpu.c
@@ -1604,7 +1604,7 @@ int __init pcpu_setup_first_chunk(const
unit_off = alloc_bootmem(nr_cpu_ids * sizeof(unit_off[0]));

for (cpu = 0; cpu < nr_cpu_ids; cpu++)
- unit_map[cpu] = NR_CPUS;
+ unit_map[cpu] = UINT_MAX;
pcpu_first_unit_cpu = NR_CPUS;

for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
@@ -1619,7 +1619,7 @@ int __init pcpu_setup_first_chunk(const
continue;

BUG_ON(cpu > nr_cpu_ids || !cpu_possible(cpu));
- BUG_ON(unit_map[cpu] != NR_CPUS);
+ BUG_ON(unit_map[cpu] != UINT_MAX);

unit_map[cpu] = unit + i;
unit_off[cpu] = gi->base_offset + i * ai->unit_size;
@@ -1632,7 +1632,7 @@ int __init pcpu_setup_first_chunk(const
pcpu_nr_units = unit;

for_each_possible_cpu(cpu)
- BUG_ON(unit_map[cpu] == NR_CPUS);
+ BUG_ON(unit_map[cpu] == UINT_MAX);

pcpu_nr_groups = ai->nr_groups;
pcpu_group_offsets = group_offsets;

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