Messages in this thread Patch in this message | | | From | Masayoshi Mizuma <> | Subject | [PATCH] sched/debug: initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK | Date | Tue, 29 Jan 2019 10:12:45 -0500 |
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From: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
register_sched_domain_sysctl() copies the cpu_possible_mask into sd_sysctl_cpus, but only if sd_sysctl_cpus hasn't already been allocated (ie, CONFIG_CPUMASK_OFFSTACK is set). However, when CONFIG_CPUMASK_OFFSTACK is not set, sd_sysctl_cpus is left uninitialized (all zeroes) and the kernel may fail to initialize sched_domain sysctl entries for all possible cpus.
This is visible to the user if the kernel is booted with maxcpus=n, or if ACPI tables have been modified to leave cpus offline, and then checking for missing /proc/sys/kernel/sched_domain/cpu* entries.
Fix this by separating the allocataion and initialization, and adding a flag to initialize the possible cpu entries while system booting only.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Tested-by: Syuuichirou Ishii <ishii.shuuichir@jp.fujitsu.com> Tested-by: Tarumizu, Kohei <tarumizu.kohei@jp.fujitsu.com> --- kernel/sched/debug.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index de3de997e245..9c6637f3e21d 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -310,6 +310,7 @@ static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu) static cpumask_var_t sd_sysctl_cpus; static struct ctl_table_header *sd_sysctl_header; +static int register_sched_domain_sysctl_on_boot = 1; void register_sched_domain_sysctl(void) { @@ -344,9 +345,12 @@ void register_sched_domain_sysctl(void) if (!cpumask_available(sd_sysctl_cpus)) { if (!alloc_cpumask_var(&sd_sysctl_cpus, GFP_KERNEL)) return; + } + if (register_sched_domain_sysctl_on_boot) { /* init to possible to not have holes in @cpu_entries */ cpumask_copy(sd_sysctl_cpus, cpu_possible_mask); + register_sched_domain_sysctl_on_boot = 0; } for_each_cpu(i, sd_sysctl_cpus) { -- 2.20.1
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