sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK

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 allocation and initialization, and adding a
flag to initialize the possible CPU entries while system booting only.

Tested-by: Syuuichirou Ishii <[email protected]>
Tested-by: Tarumizu, Kohei <[email protected]>
Signed-off-by: Hidetoshi Seto <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Masayoshi Mizuma <[email protected]>
Acked-by: Joe Lawrence <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Masayoshi Mizuma <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions