cpulist_parse() uses nr_cpumask_bits as a limit to parse the
passed buffer from kernel commandline. What nr_cpumask_bits
represents varies depending upon the CONFIG_CPUMASK_OFFSTACK option:
- If CONFIG_CPUMASK_OFFSTACK=n, then nr_cpumask_bits is the same as
NR_CPUS, which might not represent the # of CPUs that really exist
(default 64). So, there's a chance of a gap between nr_cpu_ids
and NR_CPUS, which ultimately lead towards invalid cpulist_parse()
operation. For example, if isolcpus=9 is passed on an 8 cpu
system (CONFIG_CPUMASK_OFFSTACK=n) it doesn't show the error
that it's supposed to.
This patch fixes this bug by finding the last CPU of the passed
isolcpus= list and checking it against nr_cpu_ids.
It also fixes the error message where the nr_cpu_ids should be
nr_cpu_ids-1, since CPU numbering starts from 0.
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adobriyan@gmail.com
Cc: akpm@linux-foundation.org
Cc: longman@redhat.com
Cc: mka@chromium.org
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/20171023130154.9050-1-rakib.mullick@gmail.com
[ Enhanced the changelog and the kernel message. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
include/linux/cpumask.h | 16 ++++++++++++++++
kernel/sched/topology.c | 4 ++--
2 files changed, 18 insertions(+), 2 deletions(-)
e22cdc3fc5