Message-ID: <20130724214847.GA31914@1wt.eu>
Date:	Wed, 24 Jul 2013 23:48:47 +0200
From:	Willy Tarreau <w@....eu>
To:	"Rich, Jason" <jason.rich@...comms.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Stoltenberg, Matthew" <matthew.stoltenberg@...comms.com>,
	James.Bottomley@...e.de
Subject: Re: Panic at _blk_run_queue on 2.6.32

Hi Jason,

On Wed, Jul 24, 2013 at 09:29:32PM +0000, Rich, Jason wrote:
> > -----Original Message-----
> > From: linux-kernel-owner@...r.kernel.org [mailto:linux-kernel-
> > owner@...r.kernel.org] On Behalf Of Rich, Jason
> > Sent: Monday, July 22, 2013 4:15 PM
> > To: Willy Tarreau
> > Cc: linux-kernel@...r.kernel.org
> > Subject: RE: Panic at _blk_run_queue on 2.6.32
> > 
> > > -----Original Message-----
> > > From: linux-kernel-owner@...r.kernel.org [mailto:linux-kernel-
> > > owner@...r.kernel.org] On Behalf Of Willy Tarreau
> > > Sent: Monday, July 22, 2013 4:04 AM
> > > To: Rich, Jason
> > > Cc: linux-kernel@...r.kernel.org
> > > Subject: Re: Panic at _blk_run_queue on 2.6.32
> > >
> > > Hi Jason,
> > >
> > > On Fri, Jul 19, 2013 at 02:38:45PM +0000, Rich, Jason wrote:
> > > > Just a small update from this week of trying to narrow it down.
> > > > Long story
> > > short I've gotten about 3 bisects in.  The failures are appearing less
> > > often than previously seen on these two particular machines.  It feels
> > > like maybe
> > > 1/40 reboots.  In any case, finding a "good" revision of kernel code
> > > will require me to run my test at least overnight to be sure.  My test
> > > is a simple reboot the system every 5 minutes.  When it crashes, I
> > > have a terminal window open to show it hung up.
> > > > In case you are actively poking around, I've ruled out quite a bit
> > > > so far.  If I
> > > understand bisect correctly (this is my first time to use it
> > > actually), it took me below 2.6.32.42's tag.
> > > > Bisect log:
> > > > # bad: [60b1e4f20a6cf45f07d2aef7eecd7fd58007ff1e] Linux 2.6.32.50 #
> > > > good: [145fff1f0b75c8bd6a26052d638276bb2e009983] Linux 2.6.32.39 git
> > > > bisect start 'v2.6.32.50' 'v2.6.32.39'
> > > > # bad: [1ff36a0e02f978e533b13ce6a86ad6a73444cec8] cfq-iosched: fix
> > > > locking around ioc->ioc_data assignment git bisect bad
> > > > 1ff36a0e02f978e533b13ce6a86ad6a73444cec8
> > > > # bad: [1183c16343f6daff3e418f8c782ce924f52ae148] tehuti: Firmware
> > > > filename is tehuti/bdx.bin git bisect bad
> > > > 1183c16343f6daff3e418f8c782ce924f52ae148
> > > > # bad: [0ec1c448546ccd6413dd864bf007a13a3af4c7c4] SUNRPC: fix NFS
> > > > client over TCP hangs due to packet loss (Bug 16494) git bisect bad
> > > > 0ec1c448546ccd6413dd864bf007a13a3af4c7c4
> > >
> > > Thanks, this is extremely useful. There are only 68 patches left, many
> > > of which are very unlikely related to your issue (last commit at top,
> > > 2.6.32.39 at
> > > bottom) :
> > >
> > > 0ec1c44 SUNRPC: fix NFS client over TCP hangs due to packet loss (Bug
> > > 16494)
> > > 0682ff5 GFS2: BUG in gfs2_adjust_quota a03167a GFS2: Fix writing to
> > > non-page aligned gfs2_quota structures 120011e
> > > GFS2: Clean up gfs2_adjust_quota() and do_glock() a89861f USB: teach
> > > "devices" file about Wireless and SuperSpeed USB
> > > 5e35287 USB: don't enable remote wakeup by default
> > > a30ded7 USB: retain USB device power/wakeup setting across
> > > reconfiguration
> > > 8982267 Staging: rtl8192su: add device ids
> > > 1bc5b01 Staging: rtl8192su: remove device ids
> > > b064372 Staging: rtl8192su: Fix procfs code for interfaces not named
> > > wlan0
> > > b2186d3 Staging: rtl8192su: Clean up in case of an error in module
> > > initialisation
> > > 0eec020 Staging: rtl8192su: check for skb == NULL
> > > 276c429 Input: elantech - discard the first 2 positions on some
> > > firmwares 1747aac Input: elantech - relax signature checks
> > > 8bac623 Input: elantech - use all 3 bytes when checking version
> > > 6883f58 Input: elantech - ignore high bits in the position coordinates
> > > c96981d
> > > Input: elantech - allow forcing Elantech protocol 971c6df Input:
> > > elantech - fix firmware version check
> > > 40ebeb0 Input: elantech - do not advertise relative events
> > > 450aae0 Input: Add support of Synaptics Clickpad device
> > > 92da734 tms380tr: declare MODULE_FIRMWARE
> > > 89d3e39 spider-net: declare MODULE_FIRMWARE
> > > b6b42e9 pcnet-cs: declare MODULE_FIRMWARE 65bddae netx: declare
> > > MODULE_FIRMWARE 75d0a9b myri10ge: declare MODULE_FIRMWARE
> > > 7395c67 cxgb3: declare MODULE_FIRMWARE
> > > c90f931 bnx2x: declare MODULE_FIRMWARE
> > > c23a103 netxen: module firmware hints
> > > cd60404 fs/partitions/ldm.c: fix oops caused by corrupted partition
> > > table
> > > d459e08 can: Add missing socket check in can/bcm release.
> > > 1c89151 Open with O_CREAT flag set fails to open existing files on non
> > > writable directories 726f22c Fix gcc 4.5.1 miscompiling
> > > drivers/char/i8k.c
> > > (again) 88e424f i8k: Tell gcc that *regs gets clobbered
> > > f40fe91 ARM: 6891/1: prevent heap corruption in OABI semtimedop
> > > 1edf9b9 af_unix: Only allow recv on connected seqpacket sockets.
> > > 8153163 x86, AMD: Fix APIC timer erratum 400 affecting K8 Rev.A-E
> > > processors
> > > eeea5b0 USB: fix regression in usbip by setting has_tt flag 9b3315a mmc:
> > > sdhci: Check mrq != NULL in sdhci_tasklet_finish
> > > 3de4df1 mmc: sdhci: Check mrq->cmd in sdhci_tasklet_finish d98a8df mmc:
> > > sdhci-pci: Fix error case in sdhci_pci_probe_slot()
> > > 0ccd644 put stricter guards on queue dead checks
> > > e79b858 mpt2sas: prevent heap overflows and unchecked reads 32334ea
> > > pmcraid: reject negative request size
> > > 5a6e9f0 Input: xen-kbdfront - fix mouse getting stuck after
> > > save/restore
> > > 5dd27a4 agp: fix OOM and buffer overflow 148dc7b agp: fix arbitrary
> > > kernel memory writes
> > > e411ea9 NFSv4.1: Ensure state manager thread dies on last umount
> > > 9aa8b9c
> > > nfs: don't lose MS_SYNCHRONOUS on remount of noac mount 0d1877d
> > > m68k/mm: Set all online nodes in N_NORMAL_MEMORY d93ec4a
> > FLEXCOP-
> > > PCI: fix __xlate_proc_name-warning for flexcop-pci
> > > ec9c795 set memory ranges in N_NORMAL_MEMORY when onlined
> > > 8ba5e32 slub: fix panic with DISCONTIGMEM
> > > 548a4a8 udp: Fix bogus UFO packet generation
> > > 71447f8 atl1c: duplicate atl1c_get_tpd
> > > 6f63415 iwlagn: Support new 5000 microcode.
> > > 16933b0 dasd: correct device table
> > > 95204a5 Remove extra struct page member from the buffer info structure
> > > e18aff3 UBIFS: fix master node recovery 98b75ef kconfig: Avoid buffer
> > > underrun in choice input
> > > a738488 ASoC: Fix output PGA enabling in wm_hubs CODECs
> > > e028e89 serial/imx: read cts state only after acking cts change irq
> > > 16b0c22 NFS: nfs_wcc_update_inode() should set nfsi->attr_gencount
> > > e8ab09a drm/radeon/kms: fix bad shift in atom iio table parser d9a176c
> > > intel-
> > > iommu: Fix get_domain_for_dev() error path
> > > 5cf96f2 intel-iommu: Unlink domain from iommu
> > > ef6fc37 p54: Initialize extra_len in p54_tx_80211 752bdca block,
> > > blk-sysfs: Fix an err return path in blk_register_queue()
> > > ed11df0 ath: add missing regdomain pair 0x5c mapping
> > >
> > > If you're running on an AMD CPU, maybe you'd like to try reverting this one
> > :
> > > 8153163 x86, AMD: Fix APIC timer erratum 400 affecting K8 Rev.A-E
> > > processors
> > >
> > > If you're running with an NFS client, you'll probably want to try
> > > without
> > > 0ec1c44 SUNRPC: fix NFS client over TCP hangs due to packet loss (Bug
> > > 16494)
> > >
> > > It's also possibly that it's not a kernel hang at boot but an unmount
> > > that never completes in the reboot scripts or something like this
> > > (hence the possibility of the NFS client above).
> > >
> > > Thanks!
> > > Willy
> > 
> > 
> > I don't have any AMDs - only intel Xeons.  That said, I think you are most
> > likely correct about the NFS issue.  I do use NFS heavily on these systems.
> > That said, the host that is failing to boot up all of the way is the server, not
> > the client side of NFS.  Not sure if that matters.  Anyway, the bisecting
> > continues.
> > -Jason
> 
> Greetings Willy,
> Results are in from my bisecting.

Excellent, that's really great that you managed to find this! I have
copied James, who authored this patch, in case this reminds him anything.
I'll also dig in newer kernels to see if some other patch was added later
on top of this one.

> They are below, but I'd also like to
> mention I'm going to be MIA for about 2 weeks.  I'm handing this off to a
> co-worker (Matt Stoltenberg) while I'm out.  So if you need any more
> information, feel free to ping him.

OK thank you.

> Other than that, let me know what the next steps will be and I'll help where
> I can.  Thanks again for the help.

Thanks to you first. I'll look for any potentially missing patch after
this one in newer kernels and will keep you informed. If I can't find
anything, I'll need James' advice on the subject, and maybe we'll need
more information about your setup, etc...

> 0ccd644ce6a803b4f7ae5b3b4da614b8a51037cc is the first bad commit
> commit 0ccd644ce6a803b4f7ae5b3b4da614b8a51037cc
> Author: James Bottomley <James.Bottomley@...e.de>
> Date:   Fri Apr 22 10:39:59 2011 -0500
>     put stricter guards on queue dead checks
>     
>     commit 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b upstream.
>     
>     SCSI uses request_queue->queuedata == NULL as a signal that the queue
>     is dying.  We set this state in the sdev release function.  However,
>     this allows a small window where we release the last reference but
>     haven't quite got to this stage yet and so something will try to take
>     a reference in scsi_request_fn and oops.  It's very rare, but we had a
>     report here, so we're pushing this as a bug fix
>     
>     The actual fix is to set request_queue->queuedata to NULL in
>     scsi_remove_device() before we drop the reference.  This causes
>     correct automatic rejects from scsi_request_fn as people who hold
>     additional references try to submit work and prevents anything from
>     getting a new reference to the sdev that way.
>     
>     Signed-off-by: James Bottomley <James.Bottomley@...e.de>
>     Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> :040000 040000 2f615395b8283bc231aef44f6c81bdd44b1b6d27 875afc4b1a9e38ce1e8fa3083f0e587ee8ce5197 M	drivers


Thanks!
Willy

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