Date:	Thu, 6 Feb 2014 06:26:09 -0800
From:	Dan Williams <dan.j.williams@...el.com>
To:	Sander Eikelenboom <linux@...elenboom.it>
Cc:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Wei Liu <wei.liu2@...rix.com>,
	Francois Romieu <romieu@...zoreil.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: 3.14-mw regression: rtl8169 WARNING: DMA-API: exceeded 7
 overlapping mappings of pfn 55ebe

On Thu, Feb 6, 2014 at 5:09 AM, Sander Eikelenboom <linux@...elenboom.it> wrote:
> Hmm ok that last message was false .. sorry for that .. it did happen again without r8169.use_dac=1, it just doesn't seem to happen all the time...
>
> Konrad / Wei, do you happen to know of any xen related change that went into 3.14 merge window that relates to dma / xen networking ?
>
> --
> Sander
>
> complete stacktrace:
>
> [  342.710738] ------------[ cut here ]------------
> [  342.726890] WARNING: CPU: 0 PID: 0 at lib/dma-debug.c:491 add_dma_entry+0x105/0x130()
> [  342.743210] DMA-API: exceeded 7 overlapping mappings of pfn 40b00
> [  342.759510] Modules linked in:
> [  342.775557] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.14.0-rc1-20140206-pcireset-net-btrevert+ #1
> [  342.791706] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640)  , BIOS V1.8B1 09/13/2010
> [  342.807627]  0000000000000009 ffff88005f603828 ffffffff81ad29fc ffffffff822134e0
> [  342.823430]  ffff88005f603878 ffff88005f603868 ffffffff810bdf62 ffff880000000000
> [  342.839081]  0000000000040b00 00000000ffffffef ffffffff822102e0 ffff8800592b9098
> [  342.854572] Call Trace:
> [  342.869748]  <IRQ>  [<ffffffff81ad29fc>] dump_stack+0x46/0x58
> [  342.884915]  [<ffffffff810bdf62>] warn_slowpath_common+0x82/0xb0
> [  342.899710]  [<ffffffff810be031>] warn_slowpath_fmt+0x41/0x50
> [  342.914395]  [<ffffffff8147853a>] ? active_pfn_read_overlap+0x3a/0x70
> [  342.929166]  [<ffffffff814792c5>] add_dma_entry+0x105/0x130
> [  342.943733]  [<ffffffff814796c6>] debug_dma_map_page+0x126/0x150
> [  342.957988]  [<ffffffff8171c8b6>] rtl8169_start_xmit+0x216/0xa20
> [  342.972306]  [<ffffffff8195f08f>] ? dev_queue_xmit_nit+0x1ef/0x260
> [  342.986523]  [<ffffffff8195eea0>] ? dev_loopback_xmit+0x1e0/0x1e0
> [  343.000689]  [<ffffffff819631e6>] dev_hard_start_xmit+0x2e6/0x4a0
> [  343.014466]  [<ffffffff81980f3e>] sch_direct_xmit+0xfe/0x280
> [  343.028052]  [<ffffffff819635dc>] __dev_queue_xmit+0x23c/0x630
> [  343.041338]  [<ffffffff819633a0>] ? dev_hard_start_xmit+0x4a0/0x4a0
> [  343.054483]  [<ffffffff81a0a334>] ? ip_output+0x54/0xf0
> [  343.067659]  [<ffffffff819639eb>] dev_queue_xmit+0xb/0x10
> [  343.080804]  [<ffffffff81a0890b>] ip_finish_output+0x2cb/0x670
> [  343.093746]  [<ffffffff81a0a334>] ? ip_output+0x54/0xf0
> [  343.106391]  [<ffffffff81a0a334>] ip_output+0x54/0xf0
> [  343.118683]  [<ffffffff81a05791>] ip_forward_finish+0x71/0x1a0
> [  343.130901]  [<ffffffff81a05a63>] ip_forward+0x1a3/0x440
> [  343.142829]  [<ffffffff810ffebb>] ? lock_is_held+0x8b/0xb0
> [  343.154346]  [<ffffffff81a035c0>] ip_rcv_finish+0x150/0x660
> [  343.165748]  [<ffffffff81a0406b>] ip_rcv+0x22b/0x370
> [  343.176838]  [<ffffffff81a60972>] ? packet_rcv_spkt+0x42/0x190
> [  343.187659]  [<ffffffff819609d2>] __netif_receive_skb_core+0x6d2/0x8a0
> [  343.198209]  [<ffffffff81960414>] ? __netif_receive_skb_core+0x114/0x8a0
> [  343.208819]  [<ffffffff81009010>] ? xen_clocksource_read+0x20/0x30
> [  343.219471]  [<ffffffff81116e49>] ? getnstimeofday+0x9/0x30
> [  343.229862]  [<ffffffff81960bbc>] __netif_receive_skb+0x1c/0x70
> [  343.239953]  [<ffffffff81960c2e>] netif_receive_skb_internal+0x1e/0xf0
> [  343.249908]  [<ffffffff81962110>] napi_gro_receive+0x70/0xa0
> [  343.259509]  [<ffffffff817198a3>] rtl8169_poll+0x2d3/0x680
> [  343.268982]  [<ffffffff81adcd2b>] ? _raw_spin_unlock_irq+0x2b/0x50
> [  343.278091]  [<ffffffff819610d1>] net_rx_action+0x161/0x260
> [  343.287056]  [<ffffffff810c28ec>] __do_softirq+0x12c/0x280
> [  343.295756]  [<ffffffff810c2da2>] irq_exit+0xa2/0xd0
> [  343.304235]  [<ffffffff814ffd5f>] xen_evtchn_do_upcall+0x2f/0x40
> [  343.312387]  [<ffffffff81adf15e>] xen_do_hypervisor_callback+0x1e/0x30
> [  343.320389]  <EOI>  [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
> [  343.328171]  [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
> [  343.335738]  [<ffffffff81008c70>] ? xen_safe_halt+0x10/0x20
> [  343.343142]  [<ffffffff81018748>] ? default_idle+0x18/0x20
> [  343.350202]  [<ffffffff81018f5e>] ? arch_cpu_idle+0x2e/0x40
> [  343.356994]  [<ffffffff8110b551>] ? cpu_startup_entry+0x91/0x1e0
> [  343.363658]  [<ffffffff81ac7d87>] ? rest_init+0xb7/0xc0
> [  343.369924]  [<ffffffff81ac7cd0>] ? csum_partial_copy_generic+0x170/0x170
> [  343.376057]  [<ffffffff8230ff1c>] ? start_kernel+0x409/0x416
> [  343.381972]  [<ffffffff8230f912>] ? repair_env_string+0x5e/0x5e
> [  343.387573]  [<ffffffff8230f5f8>] ? x86_64_start_reservations+0x2a/0x2c
> [  343.393152]  [<ffffffff82312e28>] ? xen_start_kernel+0x586/0x588
> [  343.398628] ---[ end trace 8379b598fb7ef5ee ]---
>
>
>
>
>
> Thursday, February 6, 2014, 12:36:31 PM, you wrote:
>
>> Hi Dan / Francois,
>
>> Didn't have time to test it before, but the patch doesn't seem to help.
>> I'm still getting the "DMA-API: exceeded 7 overlapping mappings of pfn 55ebe",
>> but i see now i forgot to mention i use r8169.use_dac=1 ...
>
>> Not using it seems to prevent the warning, but before 3.14 i have never seen this (with r8169.use_dac=1)

If you are still hitting this with the patch:

  59f2e7df574c dma-debug: fix overlap detection

...then I'm more inclined to think it is an actual positive report.

If you don't mind I'll send some debug patches to narrow this down.
--
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