* why we need call xennet_alloc_rx_buffers() in xennet_poll() in Netfront module?
@ 2012-11-28 4:42 David Xu
2013-01-07 16:31 ` Konrad Rzeszutek Wilk
0 siblings, 1 reply; 4+ messages in thread
From: David Xu @ 2012-11-28 4:42 UTC (permalink / raw)
To: xen-devel
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Hi all,
Why we call xennet_alloc_rx_buffers function in xennet_poll of netfront?
When I run the iperf benchmark to measure the TCP throughput between a
physical machine and a VM, the TCP server which is a Xen VM crashed.
I traced the source code and found that the error is from xennet_poll
=> xennet_alloc_rx_buffers => __skb_dequeue => __skb_unlink
1187 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1188 {
1189 struct sk_buff *skb = skb_peek(list);
1190 if (skb)
1191 __skb_unlink(skb, list);
1192 return skb;
1193 }
error is from __skb_unlink：
1166 static inline void __skb_unlink(struct sk_buff *skb, struct
sk_buff_head *list)
1167 {
1168 struct sk_buff *next, *prev;
1169
1170 list->qlen--;
1171 next = skb->next;
1172 prev = skb->prev;
1173 skb->next = skb->prev = NULL;
1174 next->prev = prev;
1175 prev->next = next;
1176 }
in this line: next->prev = prev; I found the pointer "next" is NULL
Do you know why? Thanks.
[ 100.973027] BUG: unable to handle kernel NULL pointer dereference at
0000000000000008
[ 100.973040] IP: [<ffffffff81455f16>] xennet_alloc_rx_buffers+0x166/0x350
[ 100.973050] PGD 1cc98067 PUD 1d74c067 PMD 0
[ 100.973051] Oops: 0002 [#1] SMP
[ 100.973051] CPU 1
[ 100.973051] Modules linked in:
[ 100.973051]
[ 100.973051] Pid: 9, comm: ksoftirqd/1 Not tainted 3.2.23 #131
[ 100.973051] RIP: e030:[<ffffffff81455f16>] [<ffffffff81455f16>]
xennet_alloc_rx_buffers+0x166/0x350
[ 100.973051] RSP: e02b:ffff88001e8f1c10 EFLAGS: 00010206
[ 100.973051] RAX: 0000000000000000 RBX: ffff88001da98000 RCX:
00000000000012b0
[ 100.973051] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
0000000000000256
[ 100.973051] RBP: ffff88001e8f1c60 R08: ffffc90000000000 R09:
0000000000017a41
[ 100.973051] R10: 0000000000000002 R11: 0000000000017298 R12:
ffff880019a7b700
[ 100.973051] R13: 0000000000000256 R14: 0000000000012092 R15:
0000000000000092
[ 100.973051] FS: 00007f7ace91f700(0000) GS:ffff88001fd00000(0000)
knlGS:0000000000000000
[ 100.973051] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 100.973051] CR2: 0000000000000008 CR3: 000000001da64000 CR4:
0000000000002660
[ 100.973051] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[ 100.973051] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
0000000000000400
[ 100.973051] Process ksoftirqd/1 (pid: 9, threadinfo ffff88001e8f0000,
task ffff88001e8d7000)
[ 100.973051] Stack:
[ 100.973051] 0000000000000091 ffff88001da99c80 ffff88001da99400
0000000100012091
[ 100.973051] ffff88001e8f1c60 000000000000002d ffff880019a8ac4e
ffff88001fd1a590
[ 100.973051] 0000160000000000 ffff880000000000 ffff88001e8f1db0
ffffffff8145699a
[ 100.973051] Call Trace:
[ 100.973051] [<ffffffff8145699a>] xennet_poll+0x7ca/0xe80
[ 100.973051] [<ffffffff814e3e51>] net_rx_action+0x151/0x2b0
[ 100.973051] [<ffffffff8106090d>] __do_softirq+0xbd/0x250
[ 100.973051] [<ffffffff81060b67>] run_ksoftirqd+0xc7/0x170
[ 100.973051] [<ffffffff81060aa0>] ? __do_softirq+0x250/0x250
[ 100.973051] [<ffffffff8107b0ac>] kthread+0x8c/0xa0
[ 100.973051] [<ffffffff8167ca04>] kernel_thread_helper+0x4/0x10
[ 100.973051] [<ffffffff81672d21>] ? retint_restore_args+0x13/0x13
[ 100.973051] [<ffffffff8167ca00>] ? gs_change+0x13/0x13
[ 100.973051] Code: 0f 84 19 01 00 00 83 ab 10 14 00 00 01 45 0f b6 fe 49
8b 14 24 49 8b 44 24 08 49 c7 04 24 00 00 00 00 49 c7 44 24 08 00 00 00 00
<48> 89 42 08 48 89 10 41 0f b6 d7 49 89 5c 24 20 48 8d 82 b8 01
[ 100.973051] RIP [<ffffffff81455f16>] xennet_alloc_rx_buffers+0x166/0x350
[ 100.973051] RSP <ffff88001e8f1c10>
[ 100.973051] CR2: 0000000000000008
[ 100.973259] ---[ end trace b0530821c3527d70 ]---
[ 100.973263] Kernel panic - not syncing: Fatal exception in interrupt
[ 100.973267] Pid: 9, comm: ksoftirqd/1 Tainted: G D 3.2.23 #131
[ 100.973270] Call Trace:
[ 100.973273] [<ffffffff816674ae>] panic+0x91/0x1a2
[ 100.973278] [<ffffffff8100adb2>] ? check_events+0x12/0x20
[ 100.973282] [<ffffffff81673b0a>] oops_end+0xea/0xf0
[ 100.973286] [<ffffffff81666e6b>] no_context+0x214/0x223
[ 100.973291] [<ffffffff8113cf94>] ? kmem_cache_free+0x104/0x110
[ 100.973295] [<ffffffff8166704b>] __bad_area_nosemaphore+0x1d1/0x1f0
[ 100.973299] [<ffffffff8166707d>] bad_area_nosemaphore+0x13/0x15
[ 100.973304] [<ffffffff816763fb>] do_page_fault+0x35b/0x4f0
[ 100.973308] [<ffffffff814d6044>] ? __netdev_alloc_skb+0x24/0x50
[ 100.973313] [<ffffffff8129f75a>] ? trace_hardirqs_off_thunk+0x3a/0x6c
[ 100.973318] [<ffffffff81672fa5>] page_fault+0x25/0x30
[ 100.973322] [<ffffffff81455f16>] ? xennet_alloc_rx_buffers+0x166/0x350
[ 100.973326] [<ffffffff8145699a>] xennet_poll+0x7ca/0xe80
[ 100.973330] [<ffffffff814e3e51>] net_rx_action+0x151/0x2b0
[ 100.973334] [<ffffffff8106090d>] __do_softirq+0xbd/0x250
[ 100.973338] [<ffffffff81060b67>] run_ksoftirqd+0xc7/0x170
[ 100.973342] [<ffffffff81060aa0>] ? __do_softirq+0x250/0x250
[ 100.973346] [<ffffffff8107b0ac>] kthread+0x8c/0xa0
[ 100.973350] [<ffffffff8167ca04>] kernel_thread_helper+0x4/0x10
[ 100.973354] [<ffffffff81672d21>] ? retint_restore_args+0x13/0x13
[ 100.973358] [<ffffffff8167ca00>] ? gs_change+0x13/0x13
Regards,
Cong
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: why we need call xennet_alloc_rx_buffers() in xennet_poll() in Netfront module?
2012-11-28 4:42 why we need call xennet_alloc_rx_buffers() in xennet_poll() in Netfront module? David Xu
@ 2013-01-07 16:31 ` Konrad Rzeszutek Wilk
2013-06-19 18:05 ` Deep Debroy
0 siblings, 1 reply; 4+ messages in thread
From: Konrad Rzeszutek Wilk @ 2013-01-07 16:31 UTC (permalink / raw)
To: David Xu; +Cc: xen-devel
On Tue, Nov 27, 2012 at 11:42:11PM -0500, David Xu wrote:
> Hi all,
>
> Why we call xennet_alloc_rx_buffers function in xennet_poll of netfront?
That is an easy answer - we need to allocate receive buffers :-)
>
> When I run the iperf benchmark to measure the TCP throughput between a
> physical machine and a VM, the TCP server which is a Xen VM crashed.
>
> I traced the source code and found that the error is from xennet_poll
> => xennet_alloc_rx_buffers => __skb_dequeue => __skb_unlink
Hm, that is rather strange that you would hit this. Is this problem
still present with the latest released kernel?
>
> 1187 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
> 1188 {
> 1189 struct sk_buff *skb = skb_peek(list);
> 1190 if (skb)
> 1191 __skb_unlink(skb, list);
> 1192 return skb;
> 1193 }
>
> error is from __skb_unlink：
>
> 1166 static inline void __skb_unlink(struct sk_buff *skb, struct
> sk_buff_head *list)
> 1167 {
> 1168 struct sk_buff *next, *prev;
> 1169
> 1170 list->qlen--;
> 1171 next = skb->next;
> 1172 prev = skb->prev;
> 1173 skb->next = skb->prev = NULL;
> 1174 next->prev = prev;
> 1175 prev->next = next;
> 1176 }
>
> in this line: next->prev = prev; I found the pointer "next" is NULL
>
> Do you know why? Thanks.
>
> [ 100.973027] BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000008
> [ 100.973040] IP: [<ffffffff81455f16>] xennet_alloc_rx_buffers+0x166/0x350
> [ 100.973050] PGD 1cc98067 PUD 1d74c067 PMD 0
> [ 100.973051] Oops: 0002 [#1] SMP
> [ 100.973051] CPU 1
> [ 100.973051] Modules linked in:
> [ 100.973051]
> [ 100.973051] Pid: 9, comm: ksoftirqd/1 Not tainted 3.2.23 #131
> [ 100.973051] RIP: e030:[<ffffffff81455f16>] [<ffffffff81455f16>]
> xennet_alloc_rx_buffers+0x166/0x350
> [ 100.973051] RSP: e02b:ffff88001e8f1c10 EFLAGS: 00010206
> [ 100.973051] RAX: 0000000000000000 RBX: ffff88001da98000 RCX:
> 00000000000012b0
> [ 100.973051] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
> 0000000000000256
> [ 100.973051] RBP: ffff88001e8f1c60 R08: ffffc90000000000 R09:
> 0000000000017a41
> [ 100.973051] R10: 0000000000000002 R11: 0000000000017298 R12:
> ffff880019a7b700
> [ 100.973051] R13: 0000000000000256 R14: 0000000000012092 R15:
> 0000000000000092
> [ 100.973051] FS: 00007f7ace91f700(0000) GS:ffff88001fd00000(0000)
> knlGS:0000000000000000
> [ 100.973051] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 100.973051] CR2: 0000000000000008 CR3: 000000001da64000 CR4:
> 0000000000002660
> [ 100.973051] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [ 100.973051] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
> 0000000000000400
> [ 100.973051] Process ksoftirqd/1 (pid: 9, threadinfo ffff88001e8f0000,
> task ffff88001e8d7000)
> [ 100.973051] Stack:
> [ 100.973051] 0000000000000091 ffff88001da99c80 ffff88001da99400
> 0000000100012091
> [ 100.973051] ffff88001e8f1c60 000000000000002d ffff880019a8ac4e
> ffff88001fd1a590
> [ 100.973051] 0000160000000000 ffff880000000000 ffff88001e8f1db0
> ffffffff8145699a
> [ 100.973051] Call Trace:
> [ 100.973051] [<ffffffff8145699a>] xennet_poll+0x7ca/0xe80
> [ 100.973051] [<ffffffff814e3e51>] net_rx_action+0x151/0x2b0
> [ 100.973051] [<ffffffff8106090d>] __do_softirq+0xbd/0x250
> [ 100.973051] [<ffffffff81060b67>] run_ksoftirqd+0xc7/0x170
> [ 100.973051] [<ffffffff81060aa0>] ? __do_softirq+0x250/0x250
> [ 100.973051] [<ffffffff8107b0ac>] kthread+0x8c/0xa0
> [ 100.973051] [<ffffffff8167ca04>] kernel_thread_helper+0x4/0x10
> [ 100.973051] [<ffffffff81672d21>] ? retint_restore_args+0x13/0x13
> [ 100.973051] [<ffffffff8167ca00>] ? gs_change+0x13/0x13
> [ 100.973051] Code: 0f 84 19 01 00 00 83 ab 10 14 00 00 01 45 0f b6 fe 49
> 8b 14 24 49 8b 44 24 08 49 c7 04 24 00 00 00 00 49 c7 44 24 08 00 00 00 00
> <48> 89 42 08 48 89 10 41 0f b6 d7 49 89 5c 24 20 48 8d 82 b8 01
> [ 100.973051] RIP [<ffffffff81455f16>] xennet_alloc_rx_buffers+0x166/0x350
> [ 100.973051] RSP <ffff88001e8f1c10>
> [ 100.973051] CR2: 0000000000000008
> [ 100.973259] ---[ end trace b0530821c3527d70 ]---
> [ 100.973263] Kernel panic - not syncing: Fatal exception in interrupt
> [ 100.973267] Pid: 9, comm: ksoftirqd/1 Tainted: G D 3.2.23 #131
> [ 100.973270] Call Trace:
> [ 100.973273] [<ffffffff816674ae>] panic+0x91/0x1a2
> [ 100.973278] [<ffffffff8100adb2>] ? check_events+0x12/0x20
> [ 100.973282] [<ffffffff81673b0a>] oops_end+0xea/0xf0
> [ 100.973286] [<ffffffff81666e6b>] no_context+0x214/0x223
> [ 100.973291] [<ffffffff8113cf94>] ? kmem_cache_free+0x104/0x110
> [ 100.973295] [<ffffffff8166704b>] __bad_area_nosemaphore+0x1d1/0x1f0
> [ 100.973299] [<ffffffff8166707d>] bad_area_nosemaphore+0x13/0x15
> [ 100.973304] [<ffffffff816763fb>] do_page_fault+0x35b/0x4f0
> [ 100.973308] [<ffffffff814d6044>] ? __netdev_alloc_skb+0x24/0x50
> [ 100.973313] [<ffffffff8129f75a>] ? trace_hardirqs_off_thunk+0x3a/0x6c
> [ 100.973318] [<ffffffff81672fa5>] page_fault+0x25/0x30
> [ 100.973322] [<ffffffff81455f16>] ? xennet_alloc_rx_buffers+0x166/0x350
> [ 100.973326] [<ffffffff8145699a>] xennet_poll+0x7ca/0xe80
> [ 100.973330] [<ffffffff814e3e51>] net_rx_action+0x151/0x2b0
> [ 100.973334] [<ffffffff8106090d>] __do_softirq+0xbd/0x250
> [ 100.973338] [<ffffffff81060b67>] run_ksoftirqd+0xc7/0x170
> [ 100.973342] [<ffffffff81060aa0>] ? __do_softirq+0x250/0x250
> [ 100.973346] [<ffffffff8107b0ac>] kthread+0x8c/0xa0
> [ 100.973350] [<ffffffff8167ca04>] kernel_thread_helper+0x4/0x10
> [ 100.973354] [<ffffffff81672d21>] ? retint_restore_args+0x13/0x13
> [ 100.973358] [<ffffffff8167ca00>] ? gs_change+0x13/0x13
>
> Regards,
> Cong
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
_______________________________________________
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http://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: why we need call xennet_alloc_rx_buffers() in xennet_poll() in Netfront module?
2013-01-07 16:31 ` Konrad Rzeszutek Wilk
@ 2013-06-19 18:05 ` Deep Debroy
2013-06-19 20:55 ` Wei Liu
0 siblings, 1 reply; 4+ messages in thread
From: Deep Debroy @ 2013-06-19 18:05 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk; +Cc: David Xu, xen-devel@lists.xen.org
On Mon, Jan 7, 2013 at 8:31 AM, Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> wrote:
>
> On Tue, Nov 27, 2012 at 11:42:11PM -0500, David Xu wrote:
> > Hi all,
> >
> > Why we call xennet_alloc_rx_buffers function in xennet_poll of netfront?
>
> That is an easy answer - we need to allocate receive buffers :-)
> >
> > When I run the iperf benchmark to measure the TCP throughput between a
> > physical machine and a VM, the TCP server which is a Xen VM crashed.
> >
> > I traced the source code and found that the error is from xennet_poll
> > => xennet_alloc_rx_buffers => __skb_dequeue => __skb_unlink
>
>
> Hm, that is rather strange that you would hit this. Is this problem
> still present with the latest released kernel?
Hi, I am seeing a crash in xennet_poll => xennet_alloc_rx_buffers in
an old 2.6.27 kernel under somewhat similar circumstances (iperf on
domu). Wondering if there was any specific root-cause determined for
the crash reported below or if there are any specific patches that is
expected to fix this in latest kernels that I can look at for
back-porting.
> >
> > 1187 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
> > 1188 {
> > 1189 struct sk_buff *skb = skb_peek(list);
> > 1190 if (skb)
> > 1191 __skb_unlink(skb, list);
> > 1192 return skb;
> > 1193 }
> >
> > error is from __skb_unlink：
> >
> > 1166 static inline void __skb_unlink(struct sk_buff *skb, struct
> > sk_buff_head *list)
> > 1167 {
> > 1168 struct sk_buff *next, *prev;
> > 1169
> > 1170 list->qlen--;
> > 1171 next = skb->next;
> > 1172 prev = skb->prev;
> > 1173 skb->next = skb->prev = NULL;
> > 1174 next->prev = prev;
> > 1175 prev->next = next;
> > 1176 }
> >
> > in this line: next->prev = prev; I found the pointer "next" is NULL
> >
> > Do you know why? Thanks.
> >
> > [ 100.973027] BUG: unable to handle kernel NULL pointer dereference at
> > 0000000000000008
> > [ 100.973040] IP: [<ffffffff81455f16>] xennet_alloc_rx_buffers+0x166/0x350
> > [ 100.973050] PGD 1cc98067 PUD 1d74c067 PMD 0
> > [ 100.973051] Oops: 0002 [#1] SMP
> > [ 100.973051] CPU 1
> > [ 100.973051] Modules linked in:
> > [ 100.973051]
> > [ 100.973051] Pid: 9, comm: ksoftirqd/1 Not tainted 3.2.23 #131
> > [ 100.973051] RIP: e030:[<ffffffff81455f16>] [<ffffffff81455f16>]
> > xennet_alloc_rx_buffers+0x166/0x350
> > [ 100.973051] RSP: e02b:ffff88001e8f1c10 EFLAGS: 00010206
> > [ 100.973051] RAX: 0000000000000000 RBX: ffff88001da98000 RCX:
> > 00000000000012b0
> > [ 100.973051] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
> > 0000000000000256
> > [ 100.973051] RBP: ffff88001e8f1c60 R08: ffffc90000000000 R09:
> > 0000000000017a41
> > [ 100.973051] R10: 0000000000000002 R11: 0000000000017298 R12:
> > ffff880019a7b700
> > [ 100.973051] R13: 0000000000000256 R14: 0000000000012092 R15:
> > 0000000000000092
> > [ 100.973051] FS: 00007f7ace91f700(0000) GS:ffff88001fd00000(0000)
> > knlGS:0000000000000000
> > [ 100.973051] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
> > [ 100.973051] CR2: 0000000000000008 CR3: 000000001da64000 CR4:
> > 0000000000002660
> > [ 100.973051] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> > 0000000000000000
> > [ 100.973051] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
> > 0000000000000400
> > [ 100.973051] Process ksoftirqd/1 (pid: 9, threadinfo ffff88001e8f0000,
> > task ffff88001e8d7000)
> > [ 100.973051] Stack:
> > [ 100.973051] 0000000000000091 ffff88001da99c80 ffff88001da99400
> > 0000000100012091
> > [ 100.973051] ffff88001e8f1c60 000000000000002d ffff880019a8ac4e
> > ffff88001fd1a590
> > [ 100.973051] 0000160000000000 ffff880000000000 ffff88001e8f1db0
> > ffffffff8145699a
> > [ 100.973051] Call Trace:
> > [ 100.973051] [<ffffffff8145699a>] xennet_poll+0x7ca/0xe80
> > [ 100.973051] [<ffffffff814e3e51>] net_rx_action+0x151/0x2b0
> > [ 100.973051] [<ffffffff8106090d>] __do_softirq+0xbd/0x250
> > [ 100.973051] [<ffffffff81060b67>] run_ksoftirqd+0xc7/0x170
> > [ 100.973051] [<ffffffff81060aa0>] ? __do_softirq+0x250/0x250
> > [ 100.973051] [<ffffffff8107b0ac>] kthread+0x8c/0xa0
> > [ 100.973051] [<ffffffff8167ca04>] kernel_thread_helper+0x4/0x10
> > [ 100.973051] [<ffffffff81672d21>] ? retint_restore_args+0x13/0x13
> > [ 100.973051] [<ffffffff8167ca00>] ? gs_change+0x13/0x13
> > [ 100.973051] Code: 0f 84 19 01 00 00 83 ab 10 14 00 00 01 45 0f b6 fe 49
> > 8b 14 24 49 8b 44 24 08 49 c7 04 24 00 00 00 00 49 c7 44 24 08 00 00 00 00
> > <48> 89 42 08 48 89 10 41 0f b6 d7 49 89 5c 24 20 48 8d 82 b8 01
> > [ 100.973051] RIP [<ffffffff81455f16>] xennet_alloc_rx_buffers+0x166/0x350
> > [ 100.973051] RSP <ffff88001e8f1c10>
> > [ 100.973051] CR2: 0000000000000008
> > [ 100.973259] ---[ end trace b0530821c3527d70 ]---
> > [ 100.973263] Kernel panic - not syncing: Fatal exception in interrupt
> > [ 100.973267] Pid: 9, comm: ksoftirqd/1 Tainted: G D 3.2.23 #131
> > [ 100.973270] Call Trace:
> > [ 100.973273] [<ffffffff816674ae>] panic+0x91/0x1a2
> > [ 100.973278] [<ffffffff8100adb2>] ? check_events+0x12/0x20
> > [ 100.973282] [<ffffffff81673b0a>] oops_end+0xea/0xf0
> > [ 100.973286] [<ffffffff81666e6b>] no_context+0x214/0x223
> > [ 100.973291] [<ffffffff8113cf94>] ? kmem_cache_free+0x104/0x110
> > [ 100.973295] [<ffffffff8166704b>] __bad_area_nosemaphore+0x1d1/0x1f0
> > [ 100.973299] [<ffffffff8166707d>] bad_area_nosemaphore+0x13/0x15
> > [ 100.973304] [<ffffffff816763fb>] do_page_fault+0x35b/0x4f0
> > [ 100.973308] [<ffffffff814d6044>] ? __netdev_alloc_skb+0x24/0x50
> > [ 100.973313] [<ffffffff8129f75a>] ? trace_hardirqs_off_thunk+0x3a/0x6c
> > [ 100.973318] [<ffffffff81672fa5>] page_fault+0x25/0x30
> > [ 100.973322] [<ffffffff81455f16>] ? xennet_alloc_rx_buffers+0x166/0x350
> > [ 100.973326] [<ffffffff8145699a>] xennet_poll+0x7ca/0xe80
> > [ 100.973330] [<ffffffff814e3e51>] net_rx_action+0x151/0x2b0
> > [ 100.973334] [<ffffffff8106090d>] __do_softirq+0xbd/0x250
> > [ 100.973338] [<ffffffff81060b67>] run_ksoftirqd+0xc7/0x170
> > [ 100.973342] [<ffffffff81060aa0>] ? __do_softirq+0x250/0x250
> > [ 100.973346] [<ffffffff8107b0ac>] kthread+0x8c/0xa0
> > [ 100.973350] [<ffffffff8167ca04>] kernel_thread_helper+0x4/0x10
> > [ 100.973354] [<ffffffff81672d21>] ? retint_restore_args+0x13/0x13
> > [ 100.973358] [<ffffffff8167ca00>] ? gs_change+0x13/0x13
> >
> > Regards,
> > Cong
>
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xen.org
> > http://lists.xen.org/xen-devel
>
>
> _______________________________________________
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: why we need call xennet_alloc_rx_buffers() in xennet_poll() in Netfront module?
2013-06-19 18:05 ` Deep Debroy
@ 2013-06-19 20:55 ` Wei Liu
0 siblings, 0 replies; 4+ messages in thread
From: Wei Liu @ 2013-06-19 20:55 UTC (permalink / raw)
To: Deep Debroy
Cc: David Xu, xen-devel@lists.xen.org, wei.liu2,
Konrad Rzeszutek Wilk
On Wed, Jun 19, 2013 at 11:05:40AM -0700, Deep Debroy wrote:
> On Mon, Jan 7, 2013 at 8:31 AM, Konrad Rzeszutek Wilk
> <konrad.wilk@oracle.com> wrote:
> >
> > On Tue, Nov 27, 2012 at 11:42:11PM -0500, David Xu wrote:
> > > Hi all,
> > >
> > > Why we call xennet_alloc_rx_buffers function in xennet_poll of netfront?
> >
> > That is an easy answer - we need to allocate receive buffers :-)
> > >
> > > When I run the iperf benchmark to measure the TCP throughput between a
> > > physical machine and a VM, the TCP server which is a Xen VM crashed.
> > >
> > > I traced the source code and found that the error is from xennet_poll
> > > => xennet_alloc_rx_buffers => __skb_dequeue => __skb_unlink
> >
> >
> > Hm, that is rather strange that you would hit this. Is this problem
> > still present with the latest released kernel?
>
> Hi, I am seeing a crash in xennet_poll => xennet_alloc_rx_buffers in
> an old 2.6.27 kernel under somewhat similar circumstances (iperf on
> domu). Wondering if there was any specific root-cause determined for
> the crash reported below or if there are any specific patches that is
> expected to fix this in latest kernels that I can look at for
> back-porting.
>
I skimmed the log and didn't see interesting commit logs.
2.6.27 is pretty old and I think you're pretty much on your own to look
through the git tree I'm afraid.
The rune I used:
git log v2.6.27-rc9..HEAD -- drivers/net/xen-netfront.c
Wei.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-06-19 20:55 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-11-28 4:42 why we need call xennet_alloc_rx_buffers() in xennet_poll() in Netfront module? David Xu
2013-01-07 16:31 ` Konrad Rzeszutek Wilk
2013-06-19 18:05 ` Deep Debroy
2013-06-19 20:55 ` Wei Liu
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