On Mon, 09 Sep 2013 18:32:13 +0400 Konstantin Khlebnikov <khlebni...@openvz.org> wrote:
> Luiz Capitulino wrote: > > I'm getting the following soft lockup: > > > > CPU: 6 PID: 2278 Comm: killall5 Tainted: GF 3.11.0-rc7+ #1 > > Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > > 0000000000000099 ffff88011fd83de8 ffffffff815324df 0000000000002800 > > ffffffff817d48f9 ffff88011fd83e68 ffffffff8152e669 ffff88011fd83e68 > > ffffffff00000008 ffff88011fd83e78 ffff88011fd83e18 0000004081dac040 > > Call Trace: > > <IRQ> [<ffffffff815324df>] dump_stack+0x46/0x58 > > [<ffffffff8152e669>] panic+0xbb/0x1c4 > > [<ffffffff810d03c3>] watchdog_timer_fn+0x163/0x170 > > [<ffffffff8106c691>] __run_hrtimer+0x81/0x1c0 > > [<ffffffff810d0260>] ? watchdog+0x30/0x30 > > [<ffffffff8106cea7>] hrtimer_interrupt+0x107/0x240 > > [<ffffffff8102f61b>] local_apic_timer_interrupt+0x3b/0x60 > > [<ffffffff81542465>] smp_apic_timer_interrupt+0x45/0x60 > > [<ffffffff8154124a>] apic_timer_interrupt+0x6a/0x70 > > <EOI> [<ffffffff810c2f5f>] ? audit_log_start+0xbf/0x430 > > [<ffffffff810c2fe7>] ? audit_log_start+0x147/0x430 > > [<ffffffff81079030>] ? try_to_wake_up+0x2a0/0x2a0 > > [<ffffffff810c86be>] audit_log_exit+0x6ae/0xc30 > > [<ffffffff81188662>] ? __alloc_fd+0x42/0x100 > > [<ffffffff810c98e7>] __audit_syscall_exit+0x257/0x2b0 > > [<ffffffff81540794>] sysret_audit+0x17/0x21 > > > > The reproducer is somewhat unusual: > > > > 1. Install RHEL6.5 (maybe a similar older user-space will do) > > 2. Boot the just installed system > > 3. In this first boot you'll meet the firstboot script, which > > will do some setup and (depending on your answers) it will > > reboot the machine > > 4. During that first reboot the system hangs while terminating > > all processes: > > > > Sending all processes the TERM signal... > > > > It's when the soft lockup above happens. And yes, I managed > > to get this with latest upstream kernel (HEAD fa8218def1b1) > > > > I'm reproducing it on a VM, but the first report was on bare-metal. > > > > This is what is happening: > > > > 1. audit_log_start() is called > > 2. As we have SKBs waiting in audit_skb_queue and all conditions > > evaluate to true, we sleep in wait_for_auditd() > > 3. Go to 2, until sleep_time gets negative and audit_log_start() > > just busy-waits > > > > Now, *why* this is happening is a mistery to me. I tried debugging > > it, but all I could find is that at some point the kauditd thread > > never wakes up after having called schedule(). I even tried waking > > it up before calling wait_for_auditd(), but it didn't. > > We run into the same problem in rhel6 kernel. > > "readahead-collector" uses audit interface and sometimes stuck in 'stopped' > state. Yes, please also see: http://marc.info/?l=linux-kernel&m=137818375024600&w=2 > After commit 829199197a430dade2519d54f5545c4a094393b8 > (which was backported by RH into their kernel) > audit emiters will block forever if userspace daemon cannot handle backlog. > That commit just breaks timeout condition, after timeout waiting loop turns > into busy loop until deamon dies or returns back to work. > > this trivial patch should fix that problem > > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -1215,9 +1215,10 @@ struct audit_buffer *audit_log_start(struct > audit_context *ctx, gfp_t gfp_mask, > > sleep_time = timeout_start + audit_backlog_wait_time > - > jiffies; > - if ((long)sleep_time > 0) > + if ((long)sleep_time > 0) { > wait_for_auditd(sleep_time); > - continue; > + continue; > + } > } Chuck Anderson posted a similar fix: http://marc.info/?l=linux-kernel&m=137817994623832&w=2 I still get a hang for around a minute with Chuck's fix, I believe I'll get the same thing with yours. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
