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Subject: Re: [PATCH 0/16] DMA-API debugging facility v2
From: "Michael Chan" <mchan@broadcom.com>
To: "Joerg Roedel" <joerg.roedel@amd.com>
cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "mingo@redhat.com" <mingo@redhat.com>,
       "dwmw2@infradead.org" <dwmw2@infradead.org>,
       "fujita.tomonori@lab.ntt.co.jp" <fujita.tomonori@lab.ntt.co.jp>,
       "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
       "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>
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References: <1231517970-20288-1-git-send-email-joerg.roedel@amd.com>
Date: Fri, 09 Jan 2009 13:24:24 -0800
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On Fri, 2009-01-09 at 08:19 -0800, Joerg Roedel wrote:
> 
> With the code these patches introduce driver developers can find several
> bugs of misusing the DMA-API in their drivers. But be aware, it can not
> find all possible bugs. If it finds a problem it prints out messages
> like
> 
> ------------[ cut here ]------------
> WARNING: at /data2/repos/linux.trees.git/lib/dma-debug.c:231 check_unmap+0xab/0x3d9()
> Hardware name: Toonie
> bnx2 0000:01:00.0: DMA-API: device driver tries to free DMA memory it has not allocated [device address=0x00000000011]
> Modules linked in:
> Pid: 0, comm: swapper Not tainted 2.6.28 #174
> Call Trace:
>  <IRQ>  [<ffffffff8105af3a>] warn_slowpath+0xd3/0xf2
>  [<ffffffff8107c36f>] ? find_usage_backwards+0xe2/0x116
>  [<ffffffff8107c36f>] ? find_usage_backwards+0xe2/0x116
>  [<ffffffff812efd16>] ? usb_hcd_link_urb_to_ep+0x94/0xa0
>  [<ffffffff8107c52b>] ? mark_lock+0x1c/0x364
>  [<ffffffff8107d8f7>] ? __lock_acquire+0xaec/0xb55
>  [<ffffffff8107c52b>] ? mark_lock+0x1c/0x364
>  [<ffffffff811e2b4b>] ? get_hash_bucket+0x28/0x33
>  [<ffffffff814b25a5>] ? _spin_lock_irqsave+0x69/0x75
>  [<ffffffff811e2b4b>] ? get_hash_bucket+0x28/0x33
>  [<ffffffff811e2ff2>] check_unmap+0xab/0x3d9
>  [<ffffffff8107c9ed>] ? trace_hardirqs_on_caller+0x108/0x14a
>  [<ffffffff8107ca3c>] ? trace_hardirqs_on+0xd/0xf
>  [<ffffffff811e3433>] debug_unmap_single+0x3e/0x40
>  [<ffffffff8128d2d8>] dma_unmap_single+0x3d/0x60
>  [<ffffffff8128d335>] pci_unmap_page+0x1c/0x1e
>  [<ffffffff81290759>] bnx2_poll_work+0x626/0x8cb
>  [<ffffffff8107d8f7>] ? __lock_acquire+0xaec/0xb55
>  [<ffffffff81070100>] ? run_posix_cpu_timers+0x49c/0x603
>  [<ffffffff81070000>] ? run_posix_cpu_timers+0x39c/0x603
>  [<ffffffff8107c52b>] ? mark_lock+0x1c/0x364
>  [<ffffffff8107d8f7>] ? __lock_acquire+0xaec/0xb55
>  [<ffffffff81292804>] bnx2_poll_msix+0x33/0x81
>  [<ffffffff813b6478>] net_rx_action+0x8a/0x139
>  [<ffffffff8105ff39>] __do_softirq+0x8b/0x147
>  [<ffffffff8102933c>] call_softirq+0x1c/0x34
>  [<ffffffff8102a611>] do_softirq+0x39/0x90
>  [<ffffffff8105fde8>] irq_exit+0x4e/0x98
>  [<ffffffff8102a5c2>] do_IRQ+0x11f/0x135
>  [<ffffffff81028b93>] ret_from_intr+0x0/0xf
>  <EOI> <4>---[ end trace 4339d58302097423 ]---
> 
This was triggered during pci_unmap_page() -> dma_unmap_single() where
check_unmap() did not find the entry.

The original mapping was done in bnx2 using pci_map_page().  I did not
see how the debug entry was added to the hash during the call to
pci_map_page() -> dma_map_page().  Did I miss something?

Thanks.