linux-kernel - Re: scheduling while atomic & hang.

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Date:	Wed, 03 Jul 2013 21:43:09 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: scheduling while atomic & hang.

I'll look harder at the backtrace tomorrow, but my guess is that the cpu has just gotten a scheduling interrupt (time quantum expired.)

Linus Torvalds <torvalds@...ux-foundation.org> wrote:

>On Wed, Jul 3, 2013 at 6:55 PM, Dave Jones <davej@...hat.com> wrote:
>> This is a pretty context free trace. What the hell happened here?
>
>That lack of call trace looks like it happened at the final stage of
>an interrupt or page fault or other trap that is about to return to
>user space.
>
>My guess would be that the trap/irq/whatever handler for some odd
>reason ended up with an unbalanced spinlock or something. But since
>there is no trace of it, I can't even begin to guess what it would be.
>
>Does trinity save enough pseudo-random state that it can be
>repeatable, because if it's something repeatable it might be
>interesting to see what the last few system calls and traps were...
>
>> Box is wedged, and I won't be able to get to it until Friday to poke
>it.
>
>Oh well. Adding the x86 people to the cc, since the whole
>"retint_careful" does seem imply that it's not a system call entry,
>and more likely to be something like a page fault or debug trap or
>something. Any ideas, guys?
>
>>From the " 3.10.0+" I assume this is from the merge window, and
>possibly a new failure. Do you have an actual git ID? I can heartily
>recommend CONFIG_LOCALVERSION_AUTO=y as a way to get commit ID's
>encoded in the version string (which is obviously more useful if you
>end up running mainly kernels without extra commits of your own on top
>of them - if you have your own local commits you'd still need to
>translate it into "your kernel XYZ with commits of mine on top")
>
>              Linus
>
>---
>> BUG: scheduling while atomic: trinity-child0/13280/0xefffffff
>> INFO: lockdep is turned off.
>> Modules linked in: dlci dccp_ipv6 dccp_ipv4 dccp sctp bridge 8021q
>garp stp snd_seq_dummy tun fuse hidp rfcomm bnep can_raw can_bcm
>nfnetlink phonet llc2 pppoe pppox ppp_generic slhc appletalk af_rxrpc
>ipt_ULOG irda af_key
>>  can atm scsi_transport_iscsi rds rose x25 af_802154 caif_socket ipx
>caif p8023 psnap crc_ccitt p8022 llc bluetooth nfc rfkill netrom ax25
>snd_hda_codec_realtek microcode snd_hda_codec_hdmi pcspkr snd_hda_intel
>snd_hda_codec snd_hwdep sn
>> d_seq snd_seq_device usb_debug snd_pcm e1000e snd_page_alloc
>snd_timer ptp snd pps_core soundcore xfs libcrc32c
>> CPU: 0 PID: 13280 Comm: trinity-child0 Not tainted 3.10.0+ #40
>>  0000000000000000 ffff880228533ee0 ffffffff816ec1a2 ffff880228533ef8
>>  ffffffff816e782e 0000000000000db5 ffff880228533f60 ffffffff816f42bf
>>  ffff88023bdeca40 ffff880228533fd8 ffff880228533fd8 ffff880228533fd8
>> Call Trace:
>>  [<ffffffff816ec1a2>] dump_stack+0x19/0x1b
>>  [<ffffffff816e782e>] __schedule_bug+0x61/0x70
>>  [<ffffffff816f42bf>] __schedule+0x94f/0x9c0
>>  [<ffffffff816f487e>] schedule_user+0x2e/0x70
>>  [<ffffffff816f6de4>] retint_careful+0x12/0x2e
>> BUG: scheduling while atomic: trinity-child0/13280/0xefffffff
>> INFO: lockdep is turned off.
>> Modules linked in: dlci dccp_ipv6 dccp_ipv4 dccp sctp bridge 8021q
>garp stp snd_seq_dummy tun fuse hidp rfcomm bnep can_raw can_bcm
>nfnetlink phonet llc2 pppoe pppox ppp_generic slhc appletalk af_rxrpc
>ipt_ULOG irda af_key can atm scsi_transport_iscsi rds rose x25
>af_802154 caif_socket ipx caif p8023 psnap crc_ccitt p8022 llc
>bluetooth nfc rfkill netrom ax25 snd_hda_codec_realtek microcode
>snd_hda_codec_hdmi pcspkr snd_hda_intel snd_hda_codec snd_hwdep snd_seq
>snd_seq_device usb_debug snd_pcm e1000e snd_page_alloc snd_timer ptp
>snd pps_core soundcore xfs libcrc32c
>> CPU: 0 PID: 13280 Comm: trinity-child0 Tainted: G        W    3.10.0+
>#40
>>  0000000000000000 ffff880228533e80 ffffffff816ec1a2 ffff880228533e98
>>  ffffffff816e782e ffff880228533fd8 ffff880228533f00 ffffffff816f42bf
>>  ffff88023bdeca40 ffff880228533fd8 ffff880228533fd8 ffff880228533fd8
>> Call Trace:
>>  [<ffffffff816ec1a2>] dump_stack+0x19/0x1b
>>  [<ffffffff816e782e>] __schedule_bug+0x61/0x70
>>  [<ffffffff816f42bf>] __schedule+0x94f/0x9c0
>>  [<ffffffff816f487e>] schedule_user+0x2e/0x70
>>  [<ffffffff816ff169>] int_careful+0x12/0x1e
>>  [<ffffffff816f487e>] ? schedule_user+0x2e/0x70
>>  [<ffffffff816f6de4>] ? retint_careful+0x12/0x2e
>> Kernel panic - not syncing: Aiee, killing interrupt handler!

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