Date:	Thu, 4 Jun 2009 09:02:27 +0900
From:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To:	just.for.lkml@...glemail.com
Cc:	hancockrwd@...il.com, linux-kernel@...r.kernel.org,
	linux-scsi@...r.kernel.org
Subject: Re: sata_sil24 0000:04:00.0: DMA-API: device driver frees DMA sg
 list 	with different entry count [map count=13] [unmap count=10]

On Wed, 3 Jun 2009 21:30:32 +0200
Torsten Kaiser <just.for.lkml@...glemail.com> wrote:

> On Wed, May 27, 2009 at 1:40 AM, Robert Hancock <hancockrwd@...il.com> wrote:
> > Torsten Kaiser wrote:
> >>
> >> On upgrading to 2.6.30-rc1 I enable the DMA-Debugging option
> >> CONFIG_DMA_API_DEBUG=y
> >> Since then I get the following or similar errors on each boot:
> >
> > Please retest with a newer -rc, this patch likely fixes it:
> >
> > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=5825627c9463581fd9e70f8285685889ae5bb9bb
> >
> 
> Still happens with 2.6.30-rc8 (see trace at the end of the email)
> 
> As orig_n_elem is only used two times in libata-core.c I suspected a
> corruption of the qc->sg, but adding checks for this did not trigger.
> So I looked into lib/dma-debug.c.
> It seems add_dma_entry() does not protect against adding the same
> entry twice.

Do you mean that add_dma_entry() doesn't protect against adding a new
entry identical to the existing entry, right? Then it's not a
dma-debug bug (it might be better for dma-debug to check it though),
that is, such situation should not happen. Probably, it's an IOMMU bug
or a driver bug.


> That could explain these warnings, if the hash_bucket
> returns a different entry that then has the wrong map/unmap count.
> 
> So I added WARN_ON(hash_bucket_find(bucket, entry)); before the
> hash_bucket_add(bucket, entry); in add_dma_entry();
> 
> That WARN_ON() triggered more then 1500 times until the KDE desktop
> was loaded...


btw, does 'iommu=nomerge' kernel boot option fix the problem?


> This is the first full stackdump, I dont have the real first one,
> because the dmesg buffer overflowed.
> Jun  3 21:14:07 treogen [   30.094954] ------------[ cut here ]------------
> Jun  3 21:14:07 treogen [   30.094960] WARNING: at lib/dma-debug.c:256
> add_dma_entry+0x7b/0xb0()
> Jun  3 21:14:07 treogen [   30.094964] Hardware name: KFN5-D SLI
> Jun  3 21:14:07 treogen [   30.094966] Modules linked in: msp3400
> tuner tea5767 tda8290 tuner_xc2028 xc
> 5000 tda9887 tuner_simple tuner_types mt20xx tea5761 bttv ir_common
> v4l2_common videodev v4l1_compat v4
> l2_compat_ioctl32 videobuf_dma_sg videobuf_core sg btcx_risc pata_amd tveeprom
> Jun  3 21:14:07 treogen [   30.094996] Pid: 1156, comm: md3_raid1
> Tainted: G        W  2.6.30-rc8 #3
> Jun  3 21:14:07 treogen [   30.094999] Call Trace:
> Jun  3 21:14:07 treogen [   30.095005]  [<ffffffff8041667b>] ?
> add_dma_entry+0x7b/0xb0
> Jun  3 21:14:07 treogen [   30.095012]  [<ffffffff802432e8>]
> warn_slowpath_common+0x78/0xd0
> Jun  3 21:14:07 treogen [   30.095018]  [<ffffffff8024334f>]
> warn_slowpath_null+0xf/0x20
> Jun  3 21:14:07 treogen [   30.095025]  [<ffffffff8041667b>]
> add_dma_entry+0x7b/0xb0
> Jun  3 21:14:07 treogen [   30.095031]  [<ffffffff80416db4>]
> debug_dma_map_sg+0x144/0x180
> Jun  3 21:14:07 treogen [   30.095038]  [<ffffffff804d367c>]
> ata_qc_issue+0x19c/0x310
> Jun  3 21:14:07 treogen [   30.095044]  [<ffffffff804bfca0>] ?
> scsi_done+0x0/0x20
> Jun  3 21:14:07 treogen [   30.095051]  [<ffffffff804d92a0>] ?
> ata_scsi_rw_xlat+0x0/0x210
> Jun  3 21:14:07 treogen [   30.095058]  [<ffffffff804d9558>]
> ata_scsi_translate+0xa8/0x180
> Jun  3 21:14:07 treogen [   30.095065]  [<ffffffff804bfca0>] ?
> scsi_done+0x0/0x20
> Jun  3 21:14:07 treogen [   30.095070]  [<ffffffff804dc0f1>]
> ata_scsi_queuecmd+0xb1/0x2d0
> Jun  3 21:14:07 treogen [   30.095077]  [<ffffffff804bfda3>]
> scsi_dispatch_cmd+0xe3/0x220
> Jun  3 21:14:07 treogen [   30.095084]  [<ffffffff804c5a0e>]
> scsi_request_fn+0x38e/0x480
> Jun  3 21:14:07 treogen [   30.095091]  [<ffffffff803f0ae3>]
> __generic_unplug_device+0x33/0x40
> Jun  3 21:14:07 treogen [   30.095098]  [<ffffffff803f0c09>]
> generic_unplug_device+0x29/0x40
> Jun  3 21:14:07 treogen [   30.095105]  [<ffffffff803ef92e>]
> blk_unplug+0x4e/0x60
> Jun  3 21:14:07 treogen [   30.095111]  [<ffffffff80566c7b>]
> unplug_slaves+0x9b/0xe0
> Jun  3 21:14:07 treogen [   30.095118]  [<ffffffff80569418>] raid1d+0xd68/0x1070
> Jun  3 21:14:07 treogen [   30.095124]  [<ffffffff8024dcea>] ?
> try_to_del_timer_sync+0x5a/0x70
> Jun  3 21:14:07 treogen [   30.095130]  [<ffffffff8024dd1a>] ?
> del_timer_sync+0x1a/0x30
> Jun  3 21:14:07 treogen [   30.095138]  [<ffffffff805708d4>]
> md_thread+0x54/0x140
> Jun  3 21:14:07 treogen [   30.095144]  [<ffffffff80259cf0>] ?
> autoremove_wake_function+0x0/0x40
> Jun  3 21:14:07 treogen [   30.095151]  [<ffffffff80570880>] ?
> md_thread+0x0/0x140
> Jun  3 21:14:07 treogen [   30.095158]  [<ffffffff80570880>] ?
> md_thread+0x0/0x140
> Jun  3 21:14:07 treogen [   30.095164]  [<ffffffff80259856>] kthread+0x56/0x90
> Jun  3 21:14:07 treogen [   30.095171]  [<ffffffff8020c4aa>] child_rip+0xa/0x20
> Jun  3 21:14:07 treogen [   30.095178]  [<ffffffff8020bea9>] ?
> restore_args+0x0/0x30
> Jun  3 21:14:07 treogen [   30.095184]  [<ffffffff80259800>] ? kthread+0x0/0x90
> Jun  3 21:14:07 treogen [   30.095190]  [<ffffffff8020c4a0>] ?
> child_rip+0x0/0x20
> Jun  3 21:14:07 treogen [   30.095194] ---[ end trace f87165562db78e9a ]---
> 
> Is this a bug in the DMA-API debuging or in libata / sata_sil24?
> 
> Torsten
> 
> 
> DMA-API-Warning from vanilla 2.6.30-rc8:
> Jun  3 18:52:31 treogen [  486.447661] ------------[ cut here ]------------
> Jun  3 18:52:31 treogen [  486.447684] WARNING: at lib/dma-debug.c:530
> check_unmap+0x65e/0x6a0()
> Jun  3 18:52:31 treogen [  486.447689] Hardware name: KFN5-D SLI
> Jun  3 18:52:31 treogen [  486.447694] sata_sil24 0000:04:00.0:
> DMA-API: device driver frees DMA sg lis
> t with different entry count [map count=1] [unmap count=2]
> Jun  3 18:52:31 treogen [  486.447699] Modules linked in: msp3400
> tuner tea5767 tda8290 tuner_xc2028 xc
> 5000 tda9887 tuner_simple tuner_types mt20xx tea5761 bttv ir_common
> v4l2_common videodev v4l1_compat v4
> l2_compat_ioctl32 videobuf_dma_sg videobuf_core pata_amd sg btcx_risc tveeprom
> Jun  3 18:52:31 treogen [  486.447740] Pid: 3328, comm: nxproxy Not
> tainted 2.6.30-rc8 #1
> Jun  3 18:52:31 treogen [  486.447744] Call Trace:
> Jun  3 18:52:31 treogen [  486.447748]  <IRQ>  [<ffffffff8041758e>] ?
> check_unmap+0x65e/0x6a0
> Jun  3 18:52:31 treogen [  486.447766]  [<ffffffff802432e8>]
> warn_slowpath_common+0x78/0xd0
> Jun  3 18:52:31 treogen [  486.447773]  [<ffffffff802433c4>]
> warn_slowpath_fmt+0x64/0x70
> Jun  3 18:52:31 treogen [  486.447783]  [<ffffffff804d3665>] ?
> ata_qc_issue+0x1e5/0x300
> Jun  3 18:52:31 treogen [  486.447791]  [<ffffffff804bfc70>] ?
> scsi_done+0x0/0x20
> Jun  3 18:52:31 treogen [  486.447799]  [<ffffffff804d9260>] ?
> ata_scsi_rw_xlat+0x0/0x210
> Jun  3 18:52:31 treogen [  486.447807]  [<ffffffff804d9518>] ?
> ata_scsi_translate+0xa8/0x180
> Jun  3 18:52:31 treogen [  486.447817]  [<ffffffff8068d33d>] ?
> _spin_lock_irqsave+0x1d/0x40
> Jun  3 18:52:31 treogen [  486.447824]  [<ffffffff8041758e>]
> check_unmap+0x65e/0x6a0
> Jun  3 18:52:31 treogen [  486.447831]  [<ffffffff804176de>]
> debug_dma_unmap_sg+0x10e/0x1b0
> Jun  3 18:52:31 treogen [  486.447838]  [<ffffffff804bff71>] ?
> __scsi_put_command+0x61/0xa0
> Jun  3 18:52:31 treogen [  486.447845]  [<ffffffff804d30a8>]
> ata_sg_clean+0x78/0xf0
> Jun  3 18:52:31 treogen [  486.447852]  [<ffffffff804d3155>]
> __ata_qc_complete+0x35/0x110
> Jun  3 18:52:31 treogen [  486.447862]  [<ffffffff804c69d8>] ?
> scsi_io_completion+0x398/0x530
> Jun  3 18:52:31 treogen [  486.447869]  [<ffffffff804d32ed>]
> ata_qc_complete+0xbd/0x250
> Jun  3 18:52:31 treogen [  486.447876]  [<ffffffff804d382b>]
> ata_qc_complete_multiple+0xab/0xf0
> Jun  3 18:52:31 treogen [  486.447885]  [<ffffffff804e90d9>]
> sil24_interrupt+0xb9/0x5b0
> Jun  3 18:52:31 treogen [  486.447894]  [<ffffffff80273060>]
> handle_IRQ_event+0x70/0x180
> Jun  3 18:52:31 treogen [  486.447902]  [<ffffffff8027536d>]
> handle_fasteoi_irq+0x6d/0xe0
> Jun  3 18:52:31 treogen [  486.447909]  [<ffffffff8020e42f>]
> handle_irq+0x1f/0x30
> Jun  3 18:52:31 treogen [  486.447915]  [<ffffffff8020db7a>] do_IRQ+0x6a/0xf0
> Jun  3 18:52:31 treogen [  486.447924]  [<ffffffff8020be53>]
> ret_from_intr+0x0/0xf
> Jun  3 18:52:31 treogen [  486.447927]  <EOI>  [<ffffffff802c967a>] ?
> file_move+0x3a/0x60
> Jun  3 18:52:31 treogen [  486.447939]  [<ffffffff802c9668>] ?
> file_move+0x28/0x60
> Jun  3 18:52:31 treogen [  486.447949]  [<ffffffff802c682f>] ?
> __dentry_open+0xbf/0x2e0
> Jun  3 18:52:31 treogen [  486.447957]  [<ffffffff802c6b57>] ?
> nameidata_to_filp+0x57/0x70
> Jun  3 18:52:31 treogen [  486.447963]  [<ffffffff802d51f2>] ?
> do_filp_open+0x292/0x990
> Jun  3 18:52:31 treogen [  486.447972]  [<ffffffff8064915d>] ?
> unix_ioctl+0xad/0xf0
> Jun  3 18:52:31 treogen [  486.447979]  [<ffffffff802bde9c>] ?
> get_partial_node+0x2c/0xa0
> Jun  3 18:52:31 treogen [  486.447986]  [<ffffffff802c1705>] ?
> __slab_alloc+0x95/0x480
> Jun  3 18:52:31 treogen [  486.447992]  [<ffffffff802d6b91>] ?
> vfs_ioctl+0x31/0xa0
> Jun  3 18:52:31 treogen [  486.447999]  [<ffffffff8068a817>] ?
> thread_return+0x3e/0x6f7
> Jun  3 18:52:31 treogen [  486.448007]  [<ffffffff802d25d6>] ?
> getname+0x36/0x200
> Jun  3 18:52:31 treogen [  486.448015]  [<ffffffff802df56a>] ?
> alloc_fd+0x4a/0x140
> Jun  3 18:52:31 treogen [  486.448023]  [<ffffffff802c668b>] ?
> do_sys_open+0x7b/0x110
> Jun  3 18:52:31 treogen [  486.448030]  [<ffffffff802c674b>] ?
> sys_open+0x1b/0x20
> Jun  3 18:52:31 treogen [  486.448037]  [<ffffffff8020b4eb>] ?
> system_call_fastpath+0x16/0x1b
> Jun  3 18:52:31 treogen [  486.448042] ---[ end trace 9e90cc92d8410ab6 ]---
> Jun  3 18:52:31 treogen [  486.448045] Mapped at:
> Jun  3 18:52:31 treogen [  486.448048]  [<ffffffffffffffff>] 0xffffffffffffffff
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