Re: [interval_tree_test_init] BUG: soft lockup - CPU#0 stuck for 23s! [swapper/0:1]

[Fengguang Wu]

On Tue, Nov 07, 2017 at 08:58:14AM -0800, Davidlohr Bueso wrote:
> On Tue, 07 Nov 2017, Fengguang Wu wrote:
>
> > [  265.102312] xz_dec_test: module loaded
> > [  265.111774] xz_dec_test: Create a device node with 'mknod xz_dec_test c 246 0' and write .xz files to it.
> > [  265.160320] atomic64_test: passed for x86-64 platform with CX8 and with SSE
> > [  265.181966] glob: 64 self-tests passed, 0 failed
> > [  265.196996] interval tree insert/remove
> > [  292.348094] watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [swapper/0:1]
> > [  292.348094] irq event stamp: 6190340
> > [  292.396418] hardirqs last  enabled at (6190339): [<ffffffff81fb006b>] restore_regs_and_iret+0x0/0x1d
> > [  292.396418] hardirqs last disabled at (6190340): [<ffffffff81fb0cb8>] apic_timer_interrupt+0x98/0xb0
> > [  292.396418] softirqs last  enabled at (6182242): [<ffffffff81fb2942>] __do_softirq+0x382/0x3f7
> > [  292.396418] softirqs last disabled at (6182235): [<ffffffff810b6696>] irq_exit+0x51/0x7b
> > [  292.396418] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.14.0-rc8 #40
> > [  292.396418] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
> > [  292.396418] task: ffff880072bf4040 task.stack: ffffc9000031c000
> > [  292.396418] RIP: 0010:interval_tree_insert+0x4c/0xd4
>
> That would be:
>
>     for (i = 0; i < perf_loops; i++) {
> 	 for (j = 0; j < nnodes; j++)
> 		interval_tree_insert(nodes + j, &root);
> 	 for (j = 0; j < nnodes; j++)
> 		interval_tree_remove(nodes + j, &root);
>     }
>
> Which if you are using the default params would end up doing insert() 10 million times.
> How about decrementing perf_loops, it's pretty high.

It works! Thank you!

Tested-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>

Fengguang

> diff --git a/lib/interval_tree_test.c b/lib/interval_tree_test.c
> index 0e343fd29570..1dbdf3704247 100644
> --- a/lib/interval_tree_test.c
> +++ b/lib/interval_tree_test.c
> @@ -11,7 +11,7 @@
>        MODULE_PARM_DESC(name, msg);
>
> __param(int, nnodes, 100, "Number of nodes in the interval tree");
> -__param(int, perf_loops, 100000, "Number of iterations modifying the tree");
> +__param(int, perf_loops, 1000, "Number of iterations modifying the tree");
>
> __param(int, nsearches, 100, "Number of searches to the interval tree");
> __param(int, search_loops, 10000, "Number of iterations searching the tree");
>
> If that works I guess we'd have to limit the max values for such parameters
> to avoid soft lockups. The same applies to your rbtree test report.
>
> Thanks,
> Davidlohr