Commit ffe0d5a5 authored by Tejun Heo's avatar Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Reported-and-tested-by: default avatarTony Vroon <tony@linx.net>
parent 17d857be

mm/percpu.c

+3 −3
Original line number Diff line number Diff line
@@ -1604,7 +1604,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai, 
	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 struct pcpu_alloc_info *ai, 
				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 struct pcpu_alloc_info *ai, 
	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;

CRA Git | Maintained and supported by SUSTech CRA and CCSE