Re: rcu_read_lock() used illegally while idle!

From: Paul E. McKenney
Date: Wed May 22 2013 - 06:24:15 EST

On Tue, May 21, 2013 at 01:31:00PM -0400, Dave Jones wrote:
> Back from vacation, and breaking stuff already :)
>
> -rc2, plus some small local mods that shouldn't be a cause.

Hmmm... I thought that ftrace already took care to let RCU know that
the CPU should be considered non-idle before using RCU read-side critical
sections.

Adding Steven and Frederic to CC for their insight.

Thanx, Paul

> [ 839.278967] ===============================
> [ 839.279023] [ INFO: suspicious RCU usage. ]
> [ 839.279080] 3.10.0-rc2+ #1 Not tainted
> [ 839.279129] -------------------------------
> [ 839.279185] include/linux/rcupdate.h:771 rcu_read_lock() used illegally while idle!
> [ 839.279273]
> other info that might help us debug this:
>
> [ 839.279370]
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 0
> [ 839.279497] RCU used illegally from extended quiescent state!
> [ 839.279566] 2 locks held by cc1/63645:
> [ 839.279614] #0: (&rq->lock){-.-.-.}, at: [<ffffffff816b39fd>] __schedule+0xed/0x9b0
> [ 839.279754] #1: (rcu_read_lock){.+.+..}, at: [<ffffffff8109d645>] cpuacct_charge+0x5/0x1f0
> [ 839.279895]
> stack backtrace:
> [ 839.279954] CPU: 1 PID: 63645 Comm: cc1 Not tainted 3.10.0-rc2+ #1 [loadavg: 40.57 27.55 13.39 25/277 64369]
> [ 839.280074] Hardware name: Gigabyte Technology Co., Ltd. GA-MA78GM-S2H/GA-MA78GM-S2H, BIOS F12a 04/23/2010
> [ 839.280182] 0000000000000000 ffff88010f78fcf8 ffffffff816ae383 ffff88010f78fd28
> [ 839.280301] ffffffff810b698d ffff88011c092548 000000000023d073 ffff88011c092500
> [ 839.280419] 0000000000000001 ffff88010f78fd60 ffffffff8109d7c5 ffffffff8109d645
> [ 839.280537] Call Trace:
> [ 839.280578] [<ffffffff816ae383>] dump_stack+0x19/0x1b
> [ 839.280645] [<ffffffff810b698d>] lockdep_rcu_suspicious+0xfd/0x130
> [ 839.280723] [<ffffffff8109d7c5>] cpuacct_charge+0x185/0x1f0
> [ 839.280793] [<ffffffff8109d645>] ? cpuacct_charge+0x5/0x1f0
> [ 839.280865] [<ffffffff8108dffc>] update_curr+0xec/0x240
> [ 839.283157] [<ffffffff8108f528>] put_prev_task_fair+0x228/0x480
> [ 839.285453] [<ffffffff816b3a71>] __schedule+0x161/0x9b0
> [ 839.287753] [<ffffffff816b4721>] preempt_schedule+0x51/0x80
> [ 839.290056] [<ffffffff816b4800>] ? __cond_resched_softirq+0x60/0x60
> [ 839.292347] [<ffffffff816b6824>] ? retint_careful+0x12/0x2e
> [ 839.294620] [<ffffffff810ff3cc>] ftrace_ops_control_func+0x1dc/0x210
> [ 839.296880] [<ffffffff816be280>] ftrace_call+0x5/0x2f
> [ 839.299107] [<ffffffff816b681d>] ? retint_careful+0xb/0x2e
> [ 839.301319] [<ffffffff816b4805>] ? schedule_user+0x5/0x70
> [ 839.303524] [<ffffffff816b4805>] ? schedule_user+0x5/0x70
> [ 839.305709] [<ffffffff816b6824>] ? retint_careful+0x12/0x2e
> [ 839.959586] ------------[ cut here ]------------
> [ 839.962342] WARNING: at kernel/context_tracking.c:55 user_enter+0xb5/0xd0()
> [ 839.965471] Modules linked in: 8021q garp stp mrp rfcomm cmtp kernelcapi hidp fuse phonet af_key rose caif_socket af_rxrpc caif netrom llc2 bnep can_bcm can_raw can ipt_ULOG nfnetlink l2tp_ppp l2tp_netlink l2tp_core pppoe pppox ppp_generic slhc scsi_transport_iscsi ipx x25 p8023 appletalk psnap p8022 llc irda nfc crc_ccitt rds ax25 decnet af_802154 atm kvm_amd kvm microcode edac_core btusb bluetooth serio_raw pcspkr snd_hda_codec_realtek snd_hda_intel rfkill snd_hda_codec snd_pcm r8169 mii snd_page_alloc snd_timer snd soundcore sr_mod cdrom pata_atiixp radeon backlight drm_kms_helper ttm
> [ 839.983088] CPU: 1 PID: 275 Comm: jbd2/sda5-8 Not tainted 3.10.0-rc2+ #1 [loadavg: 40.57 27.55 13.39 41/277 64411]
> [ 839.986926] Hardware name: Gigabyte Technology Co., Ltd. GA-MA78GM-S2H/GA-MA78GM-S2H, BIOS F12a 04/23/2010
> [ 839.990687] ffffffff819ffcdc ffff88011cf6d6e8 ffffffff816ae383 ffff88011cf6d720
> [ 839.994267] ffffffff81043280 0000000000000000 ffff88011cf6dfd8 00000000ffffffff
> [ 839.997861] ffff88012a8046c0 ffff88012b1d7320 ffff88011cf6d730 ffffffff8104336a
> [ 840.001431] Call Trace:
> [ 840.004284] [<ffffffff816ae383>] dump_stack+0x19/0x1b
> [ 840.007486] [<ffffffff81043280>] warn_slowpath_common+0x70/0xa0
> [ 840.010807] [<ffffffff8104336a>] warn_slowpath_null+0x1a/0x20
> [ 840.014079] [<ffffffff8113acc5>] user_enter+0xb5/0xd0
> [ 840.017255] [<ffffffff816b496d>] preempt_schedule_irq+0x7d/0x90
> [ 840.020548] [<ffffffff816b68f6>] retint_kernel+0x26/0x30
> [ 840.023760] [<ffffffff81190bf7>] ? deactivate_slab+0x627/0x740
> [ 840.027035] [<ffffffff810b83fd>] ? trace_hardirqs_on+0xd/0x10
> [ 840.030303] [<ffffffff816ac6ca>] ? __slab_alloc+0x433/0x4dd
> [ 840.033547] [<ffffffff8126bc98>] ? ext4_ext_find_extent+0x438/0x520
> [ 840.036917] [<ffffffff816be280>] ? ftrace_call+0x5/0x2f
> [ 840.040147] [<ffffffff8126bc98>] ? ext4_ext_find_extent+0x438/0x520
> [ 840.043497] [<ffffffff8126bc98>] ? ext4_ext_find_extent+0x438/0x520
> [ 840.046854] [<ffffffff8126bc98>] ? ext4_ext_find_extent+0x438/0x520
> [ 840.050171] [<ffffffff81192172>] __kmalloc+0x302/0x400
> [ 840.053339] [<ffffffff8126bc98>] ext4_ext_find_extent+0x438/0x520
> [ 840.056660] [<ffffffff812701ea>] ext4_ext_map_blocks+0x6a/0x12b0
> [ 840.059942] [<ffffffff816be280>] ? ftrace_call+0x5/0x2f
> [ 840.063114] [<ffffffff81243a4d>] ext4_map_blocks+0x23d/0x4a0
> [ 840.066325] [<ffffffff81243e40>] ? _ext4_get_block+0x190/0x190
> [ 840.069563] [<ffffffff81243d33>] _ext4_get_block+0x83/0x190
> [ 840.072754] [<ffffffff81243e56>] ext4_get_block+0x16/0x20
> [ 840.075939] [<ffffffff811e609f>] generic_block_bmap+0x3f/0x50
> [ 840.079189] [<ffffffff811e6065>] ? generic_block_bmap+0x5/0x50
> [ 840.082433] [<ffffffff81241610>] ? ext4_num_dirty_pages.isra.46+0x210/0x210
> [ 840.085817] [<ffffffff81147302>] ? mapping_tagged+0x12/0x20
> [ 840.088981] [<ffffffff8124169c>] ext4_bmap+0x8c/0xf0
> [ 840.092065] [<ffffffff811cb021>] bmap+0x21/0x30
> [ 840.095078] [<ffffffff8129b073>] jbd2_journal_bmap+0x33/0xb0
> [ 840.098238] [<ffffffff8129b175>] jbd2_journal_next_log_block+0x85/0xa0
> [ 840.101479] [<ffffffff81291728>] jbd2_journal_commit_transaction+0x8f8/0x25e0
> [ 840.104763] [<ffffffff816be280>] ? ftrace_call+0x5/0x2f
> [ 840.107774] [<ffffffff816b5b52>] ? _raw_spin_unlock_irqrestore+0x42/0x80
> [ 840.110983] [<ffffffff81297f61>] kjournald2+0xe1/0x400
> [ 840.114003] [<ffffffff81072d30>] ? wake_up_bit+0x40/0x40
> [ 840.117017] [<ffffffff81297e80>] ? commit_timeout+0x10/0x10
> [ 840.120065] [<ffffffff81071c3d>] kthread+0xed/0x100
> [ 840.123001] [<ffffffff81071b50>] ? insert_kthread_work+0x80/0x80
> [ 840.126086] [<ffffffff816be59c>] ret_from_fork+0x7c/0xb0
> [ 840.129092] [<ffffffff81071b50>] ? insert_kthread_work+0x80/0x80
> [ 840.132199] ---[ end trace 407275e2f13d1407 ]---
>
>
>
> $ grep RCU .config
> # RCU Subsystem
> CONFIG_TREE_PREEMPT_RCU=y
> CONFIG_PREEMPT_RCU=y
> CONFIG_RCU_STALL_COMMON=y
> CONFIG_RCU_USER_QS=y
> CONFIG_RCU_FANOUT=64
> CONFIG_RCU_FANOUT_LEAF=16
> # CONFIG_RCU_FANOUT_EXACT is not set
> # CONFIG_RCU_FAST_NO_HZ is not set
> # CONFIG_TREE_RCU_TRACE is not set
> CONFIG_RCU_BOOST=y
> CONFIG_RCU_BOOST_PRIO=1
> CONFIG_RCU_BOOST_DELAY=500
> CONFIG_RCU_NOCB_CPU=y
> CONFIG_RCU_NOCB_CPU_ALL=y
> CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
> # RCU Debugging
> CONFIG_PROVE_RCU=y
> # CONFIG_PROVE_RCU_REPEATEDLY is not set
> CONFIG_PROVE_RCU_DELAY=y
> CONFIG_SPARSE_RCU_POINTER=y
> # CONFIG_RCU_TORTURE_TEST is not set
> CONFIG_RCU_CPU_STALL_TIMEOUT=60
> CONFIG_RCU_CPU_STALL_VERBOSE=y
> CONFIG_RCU_CPU_STALL_INFO=y
> # CONFIG_RCU_TRACE is not set
>
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