[2.6.27.10] warn_on_slowpath on CD access

[Darren Salt <linux@youmustbejoking.demon.co.uk>]

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I'm seeing warn_on_slowpath traces if I run "gxine cdda://" with a CD in the
drive. (The test CD has a data track followed by some audio tracks, but
that's probably not important.)

The warning follows this paragraph. There is taint, but that's entirely due
to earlier warn_on_slowpath traces, all identical to this one. Hardware, if
it's relevant, is an nForce4-based board. Kernel is a locally-compiled
2.6.27.10; config is attached.


WARNING: at arch/x86/kernel/pci-nommu.c:62 nommu_map_sg+0x31/0xb2()
Modules linked in: mt2060 dvb_usb_dib0700 dib7000p dib7000m dvb_usb dib3000mc
dibx000_common dib0070 vfat fat usb_storage sd_mod radeon drm rfcomm l2cap
ip6t_LOG xt_tcpudp ip6t_REJECT nf_conntrack_ipv6 xt_state nf_conntrack
ip6table_mangle ip6table_filter ip6_tables x_tables snd_emu10k1_synth
snd_emux_synth snd_seq_virmidi snd_seq_midi_emul dvb_pll cx22702 cx88_dvb
videobuf_dvb dvb_core snd_emu10k1 snd_seq_midi cx8800 snd_rawmidi
compat_ioctl32 cx8802 cx88xx snd_util_mem ir_common videodev v4l1_compat
snd_intel8x0 tveeprom snd_hwdep sata_nv v4l2_common btcx_risc videobuf_dma_sg
btusb snd_ac97_codec videobuf_core ac97_bus snd_pcm_oss snd_mixer_oss libata
dock snd_pcm bluetooth snd_page_alloc
Pid: 9809, comm: gxine Tainted: G        W 2.6.27.10 #1

Call Trace:
 [<ffffffff802299aa>] warn_on_slowpath+0x51/0x77
 [<ffffffff80315e3f>] delay_tsc+0x15/0x27
 [<ffffffff803abf50>] do_rw_taskfile+0x1cb/0x1e3
 [<ffffffff8030da3b>] cfq_dispatch_insert+0x37/0x4a
 [<ffffffff80223668>] update_curr+0x3b/0x57
 [<ffffffff80223ff3>] dequeue_entity+0x12/0x80
 [<ffffffff802102a7>] nommu_map_sg+0x31/0xb2
 [<ffffffff803ad5d5>] ide_build_dmatable+0x29/0x127
 [<ffffffff803ad802>] ide_dma_setup+0x36/0xd0
 [<ffffffff803b1fdf>] cdrom_do_newpc_cont+0x0/0x18
 [<ffffffff803b1a99>] ide_cd_do_request+0x56b/0x5f8
 [<ffffffff803a701b>] ide_do_request+0x6c0/0x904
 [<ffffffff80306214>] elv_insert+0x81/0x19a
 [<ffffffff80309a8c>] blk_execute_rq_nowait+0x51/0x6d
 [<ffffffff80309b30>] blk_execute_rq+0x88/0xb0
 [<ffffffff80307a7e>] get_request_wait+0x3a/0xdd
 [<ffffffff80309dd2>] blk_recount_segments+0x30/0x5b
 [<ffffffff803b2113>] ide_cd_queue_pc+0xc2/0x154
 [<ffffffff803079ad>] get_request+0x19f/0x236
 [<ffffffff803b3457>] ide_cdrom_packet+0x77/0x8e
 [<ffffffff803bf476>] mmc_ioctl+0x1ec/0x1214
 [<ffffffff80210276>] nommu_map_sg+0x0/0xb2
 [<ffffffff80315e3f>] delay_tsc+0x15/0x27
 [<ffffffff803a7c27>] __ide_wait_stat+0x9b/0xc7
 [<ffffffff80223668>] update_curr+0x3b/0x57
 [<ffffffff80223f35>] __dequeue_entity+0x25/0x68
 [<ffffffff8022468f>] pick_next_task_fair+0x9a/0xaa
 [<ffffffff8024bd5e>] sync_page_killable+0x0/0x31
 [<ffffffff804b01ca>] io_schedule+0xf/0x17
 [<ffffffff8024a6d1>] sync_page+0x39/0x3e
 [<ffffffff804b0330>] __wait_on_bit_lock+0x63/0x71
 [<ffffffff8022cfa1>] current_fs_time+0x1e/0x24
 [<ffffffff803c0d71>] cdrom_ioctl+0x8d3/0xc39
 [<ffffffff8024c263>] generic_file_aio_read+0x4d4/0x534
 [<ffffffff803b11ea>] idecd_ioctl+0x149/0x15c
 [<ffffffff8024a527>] find_get_page+0x1a/0x51
 [<ffffffff8024a80b>] find_lock_page+0x22/0x54
 [<ffffffff8030afb7>] blkdev_ioctl+0x605/0x63a
 [<ffffffff802558a8>] __do_fault+0x307/0x350
 [<ffffffff80256d9c>] handle_mm_fault+0x315/0x5a4
 [<ffffffff80288741>] block_ioctl+0x1b/0x1f
 [<ffffffff8027202f>] vfs_ioctl+0x1b/0x50
 [<ffffffff80272276>] do_vfs_ioctl+0x212/0x21f
 [<ffffffff802722bf>] sys_ioctl+0x3c/0x5d
 [<ffffffff8020b11b>] system_call_fastpath+0x16/0x1b

---[ end trace 7284c9695c67e9c1 ]---

-- 
| Darren Salt    | linux or ds at              | nr. Ashington, | Toon
| RISC OS, Linux | youmustbejoking,demon,co,uk | Northumberland | Army
| + Travel less. Share transport more.           PRODUCE LESS CARBON DIOXIDE.

Eventually, every frog has to croak.


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