From mboxrd@z Thu Jan 1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 47701] New: When too many disks fall out at the same time, RCU
hangs
Date: Tue, 18 Sep 2012 23:13:09 +0000 (UTC)
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Sender: linux-scsi-owner@vger.kernel.org
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To: linux-scsi@vger.kernel.org
https://bugzilla.kernel.org/show_bug.cgi?id=47701
Summary: When too many disks fall out at the same time, RCU
hangs
Product: IO/Storage
Version: 2.5
Kernel Version: 3.5.4
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: SCSI
AssignedTo: linux-scsi@vger.kernel.org
ReportedBy: sgunderson@bigfoot.com
Regression: No
Hi,
For whatever reason, I lost all of my disks at the same time (I guess a SAS
cable fell out; I'll know tomorrow). As was expected, I/O on the machine was
not so happy afterwards; what was not so expected, was the following output on
the serial console a minute or so after:
[292657.601264] INFO: rcu_sched self-detected stall on CPU[292657.602441] INFO:
rcu_sched detected stalls on CPUs/tasks: { 6} (detected by 4, t=60002 jiffies)
[292657.602444] INFO: Stall ended before state dump start
[292657.620982] {[292657.622964] 6} (t=60024 jiffies)
Pid: 7800, comm: kworker/u:9 Not tainted 3.5.4 #1
[292657.631337] Call Trace:
[292657.634069] [] __rcu_pending+0xbd/0x417
[292657.640471] [] rcu_check_callbacks+0xd5/0x138
[292657.646765] [] update_process_times+0x3c/0x73
[292657.653050] [] tick_sched_timer+0x6a/0x93
[292657.658999] [] __run_hrtimer+0xb3/0x13e
[292657.664763] [] ? tick_nohz_handler+0xd3/0xd3
[292657.670972] [] ? __do_softirq+0x16c/0x182
[292657.676916] [] hrtimer_interrupt+0xce/0x1b0
[292657.683030] [] smp_apic_timer_interrupt+0x81/0x94
[292657.689676] [] apic_timer_interrupt+0x67/0x70
[292657.695965] [] ?
_raw_spin_unlock_irqrestore+0x9/0xb
[292657.703695] [] scsi_remove_target+0x137/0x153
[292657.709985] [] sas_rphy_remove+0x25/0x4e
[292657.715841] [] sas_rphy_delete+0x11/0x1e
[292657.721699] [] sas_port_delete+0x25/0x11a
[292657.727644] [] ? mutex_unlock+0x9/0xb
[292657.733254] [] mpt2sas_transport_port_remove+0x16f/0x190
[mpt2sas]
[292657.741576] [] _scsih_remove_device+0x58/0x84 [mpt2sas]
[292657.748731] [] _scsih_device_remove_by_handle+0xbd/0xc6
[mpt2sas]
[292657.756960] []
_scsih_sas_topology_change_event+0x422/0x46d [mpt2sas]
[292657.765531] [] ? idle_balance+0xde/0x10c
[292657.771395] [] ? _scsih_abort+0x1c1/0x1c1 [mpt2sas]
[292657.778212] [] _firmware_event_work+0x2f5/0x920
[mpt2sas]
[292657.785547] [] ? add_timer+0x17/0x1a
[292657.791058] [] ? queue_delayed_work_on+0xda/0xe8
[292657.797607] [] ? _scsih_abort+0x1c1/0x1c1 [mpt2sas]
[292657.804418] [] process_one_work+0x253/0x3c5
[292657.810534] [] worker_thread+0x1d4/0x34d
[292657.816394] [] ? rescuer_thread+0x230/0x230
[292657.822511] [] kthread+0x84/0x8c
[292657.827675] [] kernel_thread_helper+0x4/0x10
[292657.833875] [] ? kthread_freezable_should_stop+0x58/0x58
[292657.841117] [] ? gs_change+0xb/0xb
I'm reporting this primarily because it could cause problems in some other
context (say, when only one or two disks disappear); of course, for me in this
case, it wouldn't matter if I/O was "properly" rejected or the entire machine
hanged, it's useless anyway.
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