kernel-aes67/kernel/sched
Oleg Nesterov 257bf89d84 sched/isolation: Fix boot crash when maxcpus < first housekeeping CPU
housekeeping_setup() checks cpumask_intersects(present, online) to ensure
that the kernel will have at least one housekeeping CPU after smp_init(),
but this doesn't work if the maxcpus= kernel parameter limits the number of
processors available after bootup.

For example, a kernel with "maxcpus=2 nohz_full=0-2" parameters crashes at
boot time on a virtual machine with 4 CPUs.

Change housekeeping_setup() to use cpumask_first_and() and check that the
returned CPU number is valid and less than setup_max_cpus.

Another corner case is "nohz_full=0" on a machine with a single CPU or with
the maxcpus=1 kernel argument. In this case non_housekeeping_mask is empty
and tick_nohz_full_setup() makes no sense. And indeed, the kernel hits the
WARN_ON(tick_nohz_full_running) in tick_sched_do_timer().

And how should the kernel interpret the "nohz_full=" parameter? It should
be silently ignored, but currently cpulist_parse() happily returns the
empty cpumask and this leads to the same problem.

Change housekeeping_setup() to check cpumask_empty(non_housekeeping_mask)
and do nothing in this case.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240413141746.GA10008@redhat.com
2024-04-28 10:08:21 +02:00
..
Makefile sched/headers: Introduce kernel/sched/build_policy.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
autogroup.c sched/all: Change all BUG_ON() instances in the scheduler to WARN_ON_ONCE() 2022-08-12 11:25:10 +02:00
autogroup.h
build_policy.c sched: Fix missing prototype warnings 2022-05-01 10:03:43 +02:00
build_utility.c sched/headers: Remove duplicate header inclusions 2023-10-03 21:27:55 +02:00
clock.c Locking changes for v6.5: 2023-06-27 14:14:30 -07:00
completion.c sched: add a few helpers to wake up tasks on the current cpu 2023-07-17 16:08:08 -07:00
core.c RISC-V Patches for the 6.9 Merge Window 2024-03-22 10:41:13 -07:00
core_sched.c sched: Rename task_running() to task_on_cpu() 2022-09-07 21:53:47 +02:00
cpuacct.c Merge branch 'sched/fast-headers' into sched/core 2022-03-15 09:05:05 +01:00
cpudeadline.c sched/topology: Consolidate and clean up access to a CPU's max compute capacity 2023-10-09 12:59:48 +02:00
cpudeadline.h
cpufreq.c sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
cpufreq_schedutil.c sched/fair: Fix frequency selection for non-invariant case 2024-01-16 10:41:25 +01:00
cpupri.c sched/rt: Fix live lock between select_fallback_rq() and RT push 2023-09-28 22:58:13 +02:00
cpupri.h
cputime.c cputime: remove cputime_to_nsecs fallback 2022-12-27 12:52:17 +01:00
deadline.c sched/deadline: Introduce deadline servers 2023-11-15 09:57:51 +01:00
debug.c sched/fair: Simplify util_est 2023-12-23 15:59:58 +01:00
fair.c sched/eevdf: Prevent vlag from going out of bounds in reweight_eevdf() 2024-04-22 13:01:27 +02:00
features.h sched/fair: Remove SCHED_FEAT(UTIL_EST_FASTUP, true) 2023-12-23 15:59:56 +01:00
idle.c Core x86 changes for v6.9: 2024-03-11 19:53:15 -07:00
isolation.c sched/isolation: Fix boot crash when maxcpus < first housekeeping CPU 2024-04-28 10:08:21 +02:00
loadavg.c sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
membarrier.c RISC-V Patches for the 6.9 Merge Window 2024-03-22 10:41:13 -07:00
pelt.c sched: Make PELT acronym definition searchable 2023-10-13 09:56:30 +02:00
pelt.h sched/fair: Simplify util_est 2023-12-23 15:59:58 +01:00
psi.c sched/psi: Update poll => rtpoll in relevant comments 2023-10-16 13:42:49 +02:00
rt.c sched: Unify runtime accounting across classes 2023-11-15 09:57:48 +01:00
sched-pelt.h
sched.h sched: Add missing memory barrier in switch_mm_cid 2024-04-16 13:59:45 +02:00
smp.h sched, smp: Trace smp callback causing an IPI 2023-03-24 11:01:29 +01:00
stats.c sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there 2022-02-23 10:58:33 +01:00
stats.h sched/psi: Use task->psi_flags to clear in CPU migration 2022-10-30 10:12:15 +01:00
stop_task.c sched: Unify runtime accounting across classes 2023-11-15 09:57:48 +01:00
swait.c sched: add a few helpers to wake up tasks on the current cpu 2023-07-17 16:08:08 -07:00
topology.c sched/topology: Rename SD_SHARE_PKG_RESOURCES to SD_SHARE_LLC 2024-02-28 15:43:17 +01:00
wait.c sched: remove wait bookmarks 2023-10-18 14:34:18 -07:00
wait_bit.c wait_on_bit: add an acquire memory barrier 2022-08-26 09:30:25 -07:00