Date:	Tue, 10 Jun 2014 07:34:25 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:	viro@...IV.linux.org.uk, torvalds@...ux-foundation.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [pre 3.16-rc1] Oops at spin_trylock(&inode->i_lock)

On Tue, Jun 10, 2014 at 09:04:51PM +0900, Tetsuo Handa wrote:
> Hello.
> 
> I noticed that commit 59a3d4c363 "Merge branch 'core-rcu-for-linus' of
> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next" causes
> an oops when rebooting a system. Do you have any clue?

Can't say that I do.  However, the commits that might have made some
difference in how RCU operates are the following.  I have my doubts
(listed below) about their being the cause, but if the oops is reproducible,
why not try reverting each and see what happens?  Or just bisect within
the core-rcu-for-linus branches?

365187fbc04f: Update cpu_needs_another_gp() for futures from non-NOCB CPUs
	(Seems unlikely, but you never know...)

48a7639ce80c: Make callers awaken grace-period kthread
	(I could see this maybe causing a hang, but not a panic.)
	
595f3900f6b4: Replace NR_CPUS with nr_cpu_ids
	(Hard to imagine, but if nr_cpu_ids gets set late or something...)

495aa969dbae: Consolidate kfree_call_rcu() to use rcu_state pointer
	(Seems unlikely, but you never know...)

a381d757d93f: Merge rcu_sched_force_quiescent_state() with rcu_force_quiescent_state()
	(Seems unlikely, but you never know...)

5057f55e543b: Bind RCU grace-period kthreads if NO_HZ_FULL
	(Would seem more likely if NO_HZ_FULL=y in your .config.)

becb41bfe054: Make large and small sysidle systems use same state machine
	(Would seem more likely if NO_HZ_FULL_SYSIDLE=y in your .config.)

fa07a58f71ee: Replace __this_cpu_ptr() uses with raw_cpu_ptr()
	(Seems unlikely, but you never know...)

a5d6d3a1b00a: A single rcu_bh_qs() call per softirq set is enough
	(Seems unlikely, but you never know...)

							Thanx, Paul

> Config is at http://I-love.SAKURA.ne.jp/tmp/config-pre-3.16-rc1 .
> 
> ---------- console log start ----------
> EXT4-fs (sda1): re-mounted. Opts: (null)
> BUG: unable to handle kernel paging request at ffff88004c0d2f40
> IP: [<ffffffff810bc269>] do_raw_spin_trylock+0x9/0x50
> PGD 2d32067 PUD 2d35067 PMD 7fb83067 PTE 800000004c0d2060
> Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
> Modules linked in: fuse ipv6 vhost_net macvtap macvlan vhost tun ppdev snd_ens1371 snd_rawmidi snd_ac97_codec ac97_bus snd_seq snd_seq_device snd_pcm snd_timer snd soundcore e1000 dm_mod sg i2c_piix4 i2c_core parport_pc parport shpchp ext4(E) jbd2(E) mbcache(E) crc16(E) sd_mod(E) crc_t10dif(E) sr_mod(E) cdrom(E) mptspi(E) mptscsih(E) mptbase(E) scsi_transport_spi(E) pata_acpi(E) ata_generic(E) ata_piix(E)
> CPU: 2 PID: 2277 Comm: mount Tainted: G            E 3.15.0-rc8-04322-g59a3d4c #378
> Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013
> task: ffff880046d904d0 ti: ffff8800415a0000 task.ti: ffff8800415a0000
> RIP: 0010:[<ffffffff810bc269>]  [<ffffffff810bc269>] do_raw_spin_trylock+0x9/0x50
> RSP: 0018:ffff8800415a3d38  EFLAGS: 00010282
> RAX: ffff88007962c080 RBX: ffff88004c0d2f40 RCX: 0000000000000002
> RDX: 0000000000000018 RSI: ffff88004c0d4f58 RDI: ffff88004c0d2f40
> RBP: ffff8800415a3d38 R08: 0000000000000000 R09: 0000000000000001
> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88004c0d4eb0
> R13: ffff88004c0d4fb0 R14: ffff8800415a3dd8 R15: ffff88004c0d4f40
> FS:  00007fe45be4a7e0(0000) GS:ffff880079600000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffff88004c0d2f40 CR3: 00000000494b6000 CR4: 00000000000407e0
> Stack:
>  ffff8800415a3d68 ffffffff816380ee ffffffff811e3a64 ffffffff813117c9
>  ffff88004d88deb0 ffff88004c0d2eb0 ffff8800415a3db8 ffffffff811e3a80
>  ffff88004c0dafb0 ffff8800708e8fc8 ffff880046d904d0 0000000000000400
> Call Trace:
>  [<ffffffff816380ee>] _raw_spin_trylock+0x1e/0x70
>  [<ffffffff811e3a64>] ? shrink_dentry_list+0x44/0x370
>  [<ffffffff813117c9>] ? lockref_put_or_lock+0x29/0x40
>  [<ffffffff811e3a80>] shrink_dentry_list+0x60/0x370
>  [<ffffffff811e3ec9>] shrink_dcache_sb+0xd9/0x120
>  [<ffffffff811cc252>] do_remount_sb+0x52/0x1a0
>  [<ffffffff811edf8d>] ? do_remount+0x9d/0x130
>  [<ffffffff811ee015>] do_remount+0x125/0x130
>  [<ffffffff811f13f2>] do_mount+0x1b2/0x210
>  [<ffffffff8117e92b>] ? strndup_user+0x5b/0x80
>  [<ffffffff811f14e0>] SyS_mount+0x90/0xe0
>  [<ffffffff81642992>] system_call_fastpath+0x16/0x1b
> Code: ff ff ff 31 ff e8 28 ef 01 00 e9 41 ff ff ff 4c 89 ef e8 cb aa fa ff e9 44 ff ff ff 90 90 90 90 90 90 55 48 89 e5 66 66 66 66 90 <8b> 17 89 d0 c1 e8 10 66 39 c2 74 0b 31 c0 c9 c3 0f 1f 80 00 00
> RIP  [<ffffffff810bc269>] do_raw_spin_trylock+0x9/0x50
>  RSP <ffff8800415a3d38>
> CR2: ffff88004c0d2f40
> ---[ end trace 98409f38f5f1bb7f ]---
> BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:20
> in_atomic(): 1, irqs_disabled(): 1, pid: 2277, name: mount
> INFO: lockdep is turned off.
> irq event stamp: 69452
> hardirqs last  enabled at (69451): [<ffffffff810d9c6c>] __call_rcu.clone.0+0x14c/0x330
> hardirqs last disabled at (69452): [<ffffffff81639753>] error_sti+0x5/0x6
> softirqs last  enabled at (68978): [<ffffffff8105b691>] __do_softirq+0x1e1/0x420
> softirqs last disabled at (68969): [<ffffffff8105ba05>] irq_exit+0xc5/0xd0
> CPU: 2 PID: 2277 Comm: mount Tainted: G      D     E 3.15.0-rc8-04322-g59a3d4c #378
> Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013
>  ffffffff81a0d7a3 ffff8800415a3998 ffffffff8163284a ffff8800415a3998
>  ffff880046d904d0 ffff8800415a39c8 ffffffff8108ce85 ffff880046d904d0
>  ffff880047415eb8 0000000000000009 0000000000000009 ffff8800415a39f8
> Call Trace:
>  [<ffffffff8163284a>] dump_stack+0x51/0x6f
>  [<ffffffff8108ce85>] __might_sleep+0x175/0x230
>  [<ffffffff81637026>] down_read+0x26/0xa0
>  [<ffffffff8106aa44>] exit_signals+0x24/0x140
>  [<ffffffff81058bb5>] do_exit+0xb5/0x570
>  [<ffffffff8163a161>] oops_end+0xa1/0xf0
>  [<ffffffff81045f5e>] no_context+0x12e/0x200
>  [<ffffffff8104615d>] __bad_area_nosemaphore+0x12d/0x230
>  [<ffffffff810b70b5>] ? __lock_acquire+0x445/0x600
>  [<ffffffff81046273>] bad_area_nosemaphore+0x13/0x20
>  [<ffffffff8163cdc1>] __do_page_fault+0xe1/0x4c0
>  [<ffffffff81638d90>] ? _raw_spin_unlock_irqrestore+0x40/0x70
>  [<ffffffff8131145d>] ? trace_hardirqs_off_thunk+0x3a/0x3c
>  [<ffffffff8163d1fc>] do_page_fault+0xc/0x10
>  [<ffffffff81639552>] page_fault+0x22/0x30
>  [<ffffffff810bc269>] ? do_raw_spin_trylock+0x9/0x50
>  [<ffffffff816380ee>] _raw_spin_trylock+0x1e/0x70
>  [<ffffffff811e3a64>] ? shrink_dentry_list+0x44/0x370
>  [<ffffffff813117c9>] ? lockref_put_or_lock+0x29/0x40
>  [<ffffffff811e3a80>] shrink_dentry_list+0x60/0x370
>  [<ffffffff811e3ec9>] shrink_dcache_sb+0xd9/0x120
>  [<ffffffff811cc252>] do_remount_sb+0x52/0x1a0
>  [<ffffffff811edf8d>] ? do_remount+0x9d/0x130
>  [<ffffffff811ee015>] do_remount+0x125/0x130
>  [<ffffffff811f13f2>] do_mount+0x1b2/0x210
>  [<ffffffff8117e92b>] ? strndup_user+0x5b/0x80
>  [<ffffffff811f14e0>] SyS_mount+0x90/0xe0
>  [<ffffffff81642992>] system_call_fastpath+0x16/0x1b
> note: mount[2277] exited with preempt_count 2
> ---------- console log end ----------
> 
> ---------- bisect log start ----------
> # bad: [776edb59317ada867dfcddde40b55648beeb0078] Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next
> # good: [26fc9cd200ec839e0b3095e05ae018f27314e7aa] kernfs: move the last knowledge of sysfs out from kernfs
> # good: [f9c78b2be2cac2a7a397d489275e7d9f9ae785f2] block: move bio.c and bio-integrity.c from fs/ to block/
> # good: [681a2895486243a82547d8c9f53043eb54b53da0] Merge branch 'for-3.16/core' of git://git.kernel.dk/linux-block into next
> # good: [5da77761e6fd51f633b4f31051c4f839e01c29c0] Merge tag 'driver-core-3.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core into next
> # good: [4e857c58efeb99393cba5a5d0d8ec7117183137c] arch: Mass conversion of smp_mb__*()
> # good: [bf8102228a8bf053051f311e5486042fe0542894] intel_pstate: Improve initial busy calculation
> # good: [192a98e280e560510a62aca8cfa83b4ae7c095bb] ALSA: hda/realtek - Fix COEF widget NID for ALC260 replacer fixup
> # good: [1860e379875dfe7271c649058aeddffe5afd9d0d] Linux 3.15
> # good: [455c6fdbd219161bd09b1165f11699d6d73de11c] Linux 3.14
> # good: [d8ec26d7f8287f5788a494f56e8814210f0e64be] Linux 3.13
> # good: [5e01dc7b26d9f24f39abace5da98ccbd6a5ceb52] Linux 3.12
> # good: [6e4664525b1db28f8c4e1130957f70a94c19213e] Linux 3.11
> # good: [8bb495e3f02401ee6f76d1b1d77f3ac9f079e376] Linux 3.10
> # good: [c1be5a5b1b355d40e6cf79cc979eb66dafa24ad1] Linux 3.9
> # good: [19f949f52599ba7c3f67a5897ac6be14bfcb1200] Linux 3.8
> # good: [29594404d7fe73cd80eaa4ee8c43dcc53970c60e] Linux 3.7
> # good: [a0d271cbfed1dd50278c6b06bead3d00ba0a88f9] Linux 3.6
> # good: [28a33cbc24e4256c143dce96c7d93bf423229f92] Linux 3.5
> # good: [76e10d158efb6d4516018846f60c2ab5501900bc] Linux 3.4
> # good: [c16fa4f2ad19908a47c63d8fa436a1178438c7e7] Linux 3.3
> # good: [805a6af8dba5dfdd35ec35dc52ec0122400b2610] Linux 3.2
> # good: [c3b92c8787367a8bb53d57d9789b558f1295cc96] Linux 3.1
> # good: [02f8c6aee8df3cdc935e9bdd4f2d020306035dbe] Linux 3.0
> git bisect start '776edb59317ada867dfcddde40b55648beeb0078' '26fc9cd200ec839e0b3095e05ae018f27314e7aa' 'f9c78b2be2cac2a7a397d489275e7d9f9ae785f2' '681a2895486243a82547d8c9f53043eb54b53da0' '5da77761e6fd51f633b4f31051c4f839e01c29c0' '4e857c58efeb99393cba5a5d0d8ec7117183137c' 'bf8102228a8bf053051f311e5486042fe0542894' '192a98e280e560510a62aca8cfa83b4ae7c095bb' 'v3.15' 'v3.14' 'v3.13' 'v3.12' 'v3.11' 'v3.10' 'v3.9' 'v3.8' 'v3.7' 'v3.6' 'v3.5' 'v3.4' 'v3.3' 'v3.2' 'v3.1' 'v3.0'
> # good: [539b4f72d0da83e4d20df7cfc27dc49c00316940] staging/rtl8192u: Put EXPORT_SYMBOL just after the exported function
> git bisect good 539b4f72d0da83e4d20df7cfc27dc49c00316940
> # good: [49eb7b0750d9483c74e9c14ae6ea1e9d62481c3c] Merge tag 'tty-3.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty into next
> git bisect good 49eb7b0750d9483c74e9c14ae6ea1e9d62481c3c
> # good: [8f5759aeb88a47448cd92ab55a016d013b154a98] Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux into next
> git bisect good 8f5759aeb88a47448cd92ab55a016d013b154a98
> # good: [de6b25de4584febbe1808bc782734ae163b22c26] Merge tag 'regmap-v3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap into next
> git bisect good de6b25de4584febbe1808bc782734ae163b22c26
> # good: [312c76f1a3989b8d0c0c13fee765bb2c41f2d114] Merge tag 'regulator-v3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator into next
> git bisect good 312c76f1a3989b8d0c0c13fee765bb2c41f2d114
> # good: [48d684fdad83d7525a557e6ff9c37811b6a9947b] rcutorture: Run rcu_torture_writer at normal priority
> git bisect good 48d684fdad83d7525a557e6ff9c37811b6a9947b
> # good: [a5d6d3a1b00a0ad88f07c3a727c79b27915278e3] softirq: A single rcu_bh_qs() call per softirq set is enough
> git bisect good a5d6d3a1b00a0ad88f07c3a727c79b27915278e3
> # good: [61f38db3e3c0e4c3be0858750e2cabeadaecac0c] rcu: Provide API to suppress stall warnings while sysrc runs
> git bisect good 61f38db3e3c0e4c3be0858750e2cabeadaecac0c
> # good: [f70e3c4f8b6ab61f713e040822ec51f5de498146] CMA: correct unlock target
> git bisect good f70e3c4f8b6ab61f713e040822ec51f5de498146
> # bad: [59a3d4c3631e553357b7305dc09db1990aa6757c] Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next
> git bisect bad 59a3d4c3631e553357b7305dc09db1990aa6757c
> # good: [e14505a8d50882ff3bdd4b791b14d90a0881fa4d] Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
> git bisect good e14505a8d50882ff3bdd4b791b14d90a0881fa4d
> # good: [ff806d034ef8e9a95ff0b0532104dd65332e446b] Merge branch 'for-v3.16' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping into next
> git bisect good ff806d034ef8e9a95ff0b0532104dd65332e446b
> ---------- bisect log end ----------
> 

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