Ethan Zhao 21a24b5db1 sched/sysctl: Check user input value of sysctl_sched_time_avg ... commit 5ccba44ba1 upstream. System will hang if user set sysctl_sched_time_avg to 0: [root@XXX ~]# sysctl kernel.sched_time_avg_ms=0 Stack traceback for pid 0 0xffff883f6406c600 0 0 1 3 R 0xffff883f6406cf50 *swapper/3 ffff883f7ccc3ae8 0000000000000018 ffffffff810c4dd0 0000000000000000 0000000000017800 ffff883f7ccc3d78 0000000000000003 ffff883f7ccc3bf8 ffffffff810c4fc9 ffff883f7ccc3c08 00000000810c5043 ffff883f7ccc3c08 Call Trace: <IRQ> [<ffffffff810c4dd0>] ? update_group_capacity+0x110/0x200 [<ffffffff810c4fc9>] ? update_sd_lb_stats+0x109/0x600 [<ffffffff810c5507>] ? find_busiest_group+0x47/0x530 [<ffffffff810c5b84>] ? load_balance+0x194/0x900 [<ffffffff810ad5ca>] ? update_rq_clock.part.83+0x1a/0xe0 [<ffffffff810c6d42>] ? rebalance_domains+0x152/0x290 [<ffffffff810c6f5c>] ? run_rebalance_domains+0xdc/0x1d0 [<ffffffff8108a75b>] ? __do_softirq+0xfb/0x320 [<ffffffff8108ac85>] ? irq_exit+0x125/0x130 [<ffffffff810b3a17>] ? scheduler_ipi+0x97/0x160 [<ffffffff81052709>] ? smp_reschedule_interrupt+0x29/0x30 [<ffffffff8173a1be>] ? reschedule_interrupt+0x6e/0x80 <EOI> [<ffffffff815bc83c>] ? cpuidle_enter_state+0xcc/0x230 [<ffffffff815bc80c>] ? cpuidle_enter_state+0x9c/0x230 [<ffffffff815bc9d7>] ? cpuidle_enter+0x17/0x20 [<ffffffff810cd6dc>] ? cpu_startup_entry+0x38c/0x420 [<ffffffff81053373>] ? start_secondary+0x173/0x1e0 Because divide-by-zero error happens in function: update_group_capacity() update_cpu_capacity() scale_rt_capacity() { ... total = sched_avg_period() + delta; used = div_u64(avg, total); ... } To fix this issue, check user input value of sysctl_sched_time_avg, keep it unchanged when hitting invalid input, and set the minimum limit of sysctl_sched_time_avg to 1 ms. Reported-by: James Puthukattukaran <james.puthukattukaran@oracle.com> Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: efault@gmx.de Cc: ethan.kernel@gmail.com Cc: keescook@chromium.org Cc: mcgrof@kernel.org Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/1504504774-18253-1-git-send-email-ethan.zhao@oracle.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Steve Muckle <smuckle@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-09-05 09:18:33 +02:00
..
bpf	bpf: fix references to free_bpf_prog_info() in comments	2018-08-06 16:24:37 +02:00
configs
debug	kdb: make "mdr" command repeat	2018-05-30 07:49:17 +02:00
events	perf/core: Fix perf_output_read_group()	2018-05-30 07:49:12 +02:00
gcov	gcov: disable for COMPILE_TEST	2018-01-23 19:50:10 +01:00
irq	genirq: Make force irq threading setup more robust	2018-08-09 12:19:27 +02:00
livepatch
locking	locking/lockdep: Do not record IRQ state within lockdep code	2018-08-24 13:26:55 +02:00
power	PM / hibernate: Fix oops at snapshot_write()	2018-07-17 11:31:46 +02:00
printk	braille-console: Fix value returned by _braille_console_setup	2018-03-22 09:23:23 +01:00
rcu
sched	sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning	2018-05-30 07:49:08 +02:00
time	nohz: Fix local_timer_softirq_pending()	2018-08-09 12:19:27 +02:00
trace	tracing: Use __printf markup to silence compiler	2018-08-24 13:26:58 +02:00
.gitignore
acct.c	kernel/acct.c: fix the acct->needcheck check in check_free_space()	2018-01-10 09:27:08 +01:00
async.c	kernel/async.c: revert "async: simplify lowest_in_progress()"	2018-02-16 20:09:45 +01:00
audit_fsnotify.c
audit_tree.c
audit_watch.c
audit.c	audit: return on memory error to avoid null pointer dereference	2018-05-30 07:49:16 +02:00
audit.h
auditfilter.c	audit: allow not equal op for audit by executable	2018-08-06 16:24:38 +02:00
auditsc.c	audit: allow not equal op for audit by executable	2018-08-06 16:24:38 +02:00
backtracetest.c
bounds.c
capability.c
cgroup_freezer.c
cgroup_pids.c
cgroup.c
compat.c
configs.c
context_tracking.c
cpu_pm.c
cpu.c
cpuset.c
crash_dump.c
cred.c
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c	kernel/exit.c: avoid undefined behaviour when calling wait4()	2018-05-26 08:48:51 +02:00
extable.c
fork.c	kaiser: stack map PAGE_SIZE at THREAD_SIZE-PAGE_SIZE	2018-01-05 15:44:23 +01:00
freezer.c
futex_compat.c
futex.c	futex: futex_wake_op, fix sign_extend32 sign bits	2018-05-26 08:48:51 +02:00
groups.c	kernel: make groups_sort calling a responsibility group_info allocators	2018-01-10 09:27:10 +01:00
hung_task.c
irq_work.c
jump_label.c
kallsyms.c
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec_core.c
kexec_file.c
kexec_internal.h
kexec.c
kmod.c
kprobes.c	kprobes/x86: Fix to set RWX bits correctly before releasing trampoline	2018-04-08 11:51:56 +02:00
ksysfs.c
kthread.c
latencytop.c
Makefile
membarrier.c
memremap.c
module_signing.c
module-internal.h
module.c	module/retpoline: Warn about missing retpoline in module	2018-02-25 11:03:52 +01:00
notifier.c
nsproxy.c
padata.c
panic.c
params.c
pid_namespace.c
pid.c	pidns: disable pid allocation if pid_ns_prepare_proc() is failed in alloc_pid()	2018-04-13 19:50:03 +02:00
profile.c	profile: hide unused functions when !CONFIG_PROC_FS	2018-02-25 11:03:44 +01:00
ptrace.c
range.c
reboot.c
relay.c	kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE	2018-05-30 07:49:00 +02:00
resource.c	resource: fix integer overflow at reallocation	2018-04-24 09:32:05 +02:00
seccomp.c	seccomp: Move speculation migitation control to arch code	2018-07-25 10:18:27 +02:00
signal.c	kernel/signal.c: avoid undefined behaviour in kill_something_info	2018-05-30 07:48:52 +02:00
smp.c
smpboot.c
smpboot.h
softirq.c
stacktrace.c
stop_machine.c
sys_ni.c
sys.c	nospec: Allow getting/setting on non-current task	2018-07-25 10:18:26 +02:00
sysctl_binary.c
sysctl.c	sched/sysctl: Check user input value of sysctl_sched_time_avg	2018-09-05 09:18:33 +02:00
task_work.c
taskstats.c
test_kprobes.c
torture.c
tracepoint.c	tracepoint: Do not warn on ENOMEM	2018-05-16 10:06:47 +02:00
tsacct.c
uid16.c	kernel: make groups_sort calling a responsibility group_info allocators	2018-01-10 09:27:10 +01:00
up.c
user_namespace.c
user-return-notifier.c
user.c
utsname_sysctl.c
utsname.c
watchdog.c
workqueue_internal.h
workqueue.c	workqueue: use put_device() instead of kfree()	2018-05-30 07:49:04 +02:00