| Message ID | 1504504975-18417-1-git-send-email-ethan.zhao@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 6648fbb..423554a 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -367,7 +367,8 @@ static int sysrq_sysctl_handler(struct ctl_table *table, int write, .data = &sysctl_sched_time_avg, .maxlen = sizeof(unsigned int), .mode = 0644, - .proc_handler = proc_dointvec, + .proc_handler = proc_dointvec_minmax, + .extra1 = &one, }, #ifdef CONFIG_SCHEDSTATS {
System will hang if user set sysctl_sched_time_avg to 0 by [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); ... } Seems this issue could be reproduced on all I tried stable 4.1 - last kernel. To fix this issue, check user input value of sysctl_sched_time_avg, keep it unchanged when hit invalid input, set the min 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> --- v2: Check it at user input side in sysctl table (peterz). v3: Use proc_dointvec_minmax(). v4: Fix a too long line in descripton part. kernel/sysctl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)