-----Original Message-----
From: Alan Stern [mailto:[email protected]] 
Sent: Friday, March 15, 2013 9:08 AM
To: Kirsher, Jeffrey T; Brandeburg, Jesse; Allan, Bruce W
Cc: e1000-devel Mailing List
Subject: [E1000-devel] WARNING triggered by e100 driver

[The Intel ethernet drivers have lots of maintainers listed, so I arbitrarily 
addressed this to the first three names on the list.]

Ever since this check was added to the DMA API, I have been getting the 
following WARNING at boot:

[   45.843379] ------------[ cut here ]------------
[   45.844008] WARNING: at lib/dma-debug.c:933 check_unmap+0x5de/0x64d()
[   45.844008] Hardware name: HP dx2000 MT (EE004AA)
[   45.844008] e100 0000:01:08.0: DMA-API: device driver failed to check map 
error[device address=0x000000002c6ecf32] [size=42 bytes] [mapped as single]
[   45.844008] Modules linked in: snd_intel8x0 snd_ac97_codec ac97_bus evdev 
snd_pcm pcspkr snd_timer snd soundcore e100 snd_page_alloc mii i915 ohci_hcd(O) 
fbcon font bitblit softcursor drm_kms_helper drm fb ehci_pci(O) fbdev 
ehci_hcd(O) cfbcopyarea i2c_algo_bit fan i2c_core button uhci_hcd(O) video 
processor backlight thermal_sys usbcore usb_common cfbimgblt cfbfillrect
[   45.844008] Pid: 526, comm: nash-hotplug Tainted: G        W  O 
3.9.0-rc1AS-00031-gc7b496b-dirty #22
[   45.844008] Call Trace:
[   45.844008]  [<c1022aca>] warn_slowpath_common+0x63/0x7a
[   45.844008]  [<c11473c4>] ? check_unmap+0x5de/0x64d
[   45.844008]  [<c1022b45>] warn_slowpath_fmt+0x26/0x2a
[   45.844008]  [<c11473c4>] check_unmap+0x5de/0x64d
[   45.844008]  [<c10573d8>] ? __lock_acquire+0xc7c/0xc8b
[   45.844008]  [<c11475a4>] debug_dma_unmap_page+0x61/0x69
[   45.844008]  [<f00df845>] pci_unmap_single+0x4a/0x54 [e100]
[   45.844008]  [<f00e137b>] e100_poll+0x35a/0x3e0 [e100]
[   45.844008]  [<c106994c>] ? rcu_process_callbacks+0x145/0x3c5
[   45.844008]  [<c11e340d>] net_rx_action+0x65/0x133
[   45.844008]  [<c10280ad>] __do_softirq+0x96/0x140
[   45.844008]  [<c1028017>] ? local_bh_enable+0xd/0xd
[   45.844008]  <IRQ>  [<c102823a>] ? irq_exit+0x41/0x9a
[   45.844008]  [<c1003447>] ? do_IRQ+0x6b/0x7f
[   45.844008]  [<c1245ff1>] ? common_interrupt+0x31/0x36
[   45.844008] ---[ end trace e9161d67ae418510 ]---
[   45.844008] Mapped at:
[   45.844008]  [<c114781b>] debug_dma_map_page+0x3a/0xc3
[   45.844008]  [<f00de435>] pci_map_single+0x6a/0x74 [e100]
[   45.844008]  [<f00e0113>] e100_xmit_prepare+0x6c/0x99 [e100]
[   45.844008]  [<f00df343>] e100_exec_cb+0x6c/0xee [e100]
[   45.844008]  [<f00dfbea>] e100_xmit_frame+0x61/0xd0 [e100]

The reason for the warning is very simple: e100_xmit_prepare() calls
pci_map_single() but doesn't check the result.  Since DMA mapping requests can 
fail, this is clearly a bug.  There's even a comment about it in the source 
code.

I don't know enough about networking to fix this.  Can someone please take a 
look at it?

Thanks,

Alan Stern

Thanks Alan,

We are working on this...

Regards,
~Akeem


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------------------------------------------------------------------------------
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Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
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_______________________________________________
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To learn more about Intel&#174; Ethernet, visit 
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