* PROBLEM: skb_push called from rt2x00 panics occasionally [not found] <2018379362.52866.1391084425810.JavaMail.zimbra@opinsys.fi> @ 2014-01-30 12:33 ` Tuomas Räsänen 2014-01-30 19:39 ` Stanislaw Gruszka 0 siblings, 1 reply; 2+ messages in thread From: Tuomas Räsänen @ 2014-01-30 12:33 UTC (permalink / raw) To: Ivo van Doorn, Gertjan van Wingerde, Helmut Schaa, John W. Linville, Stanislaw Gruszka Cc: linux-wireless, users, tuomasjjrasanen, Veli-Matti Lintu ================================================= skb_push called from rt2x00 panics occasionally ================================================= We have been experiencing occasional skb_push panics with rt2x00 driver throughout the stable v3.10 -series. Problems occur with hosts acting as accesspoints, managed by hostapd 2.0. Some hosts panic reportedly several times per week, some almost never. All hosts have identical kernels and WiFi adapters. We have not been able to reproduce panics in a controlled manner. I'd be very happy to get some advice how to proceed in debugging and fixing this problem and even better, to understand the whole issue thoroughly. Unfortunately, all I know now is that the skb headroom is not big enough for the frame the AP is trying to transmit, right? Hopefully someone can shed some light on this problem. Kernel version ============== The latest tested and affected is stable v3.10.23, earlier v3.10 -kernels are affected as well. We do not have reliable test results from newer kernels due to random nature of this bug. Output ====== Unfortunately, we don't have textual traces, just photos. Here is one: http://i.imgur.com/2XD8X3r.jpg Environment =========== USB Wifi adapter ---------------- Bus 001 Device 003: ID 148f:3070 Ralink Technology, Corp. RT2870/RT3070 Wireless Adapter wlan0 Link encap:Ethernet HWaddr 00:1e:ab:20:56:30 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Wiphy phy0 Band 1: Capabilities: 0x172 HT20/HT40 Static SM Power Save RX Greenfield RX HT20 SGI RX HT40 SGI RX STBC 1-stream Max AMSDU length: 3839 bytes No DSSS/CCK HT40 Maximum RX AMPDU length 65535 bytes (exponent: 0x003) Minimum RX AMPDU time spacing: 2 usec (0x04) HT RX MCS rate indexes supported: 0-7, 32 TX unequal modulation not supported HT TX Max spatial streams: 1 HT TX MCS rate indexes supported may differ Frequencies: * 2412 MHz [1] (20.0 dBm) * 2417 MHz [2] (20.0 dBm) * 2422 MHz [3] (20.0 dBm) * 2427 MHz [4] (20.0 dBm) * 2432 MHz [5] (20.0 dBm) * 2437 MHz [6] (20.0 dBm) * 2442 MHz [7] (20.0 dBm) * 2447 MHz [8] (20.0 dBm) * 2452 MHz [9] (20.0 dBm) * 2457 MHz [10] (20.0 dBm) * 2462 MHz [11] (20.0 dBm) * 2467 MHz [12] (20.0 dBm) * 2472 MHz [13] (20.0 dBm) * 2484 MHz [14] (disabled) Bitrates (non-HT): * 1.0 Mbps * 2.0 Mbps (short preamble supported) * 5.5 Mbps (short preamble supported) * 11.0 Mbps (short preamble supported) * 6.0 Mbps * 9.0 Mbps * 12.0 Mbps * 18.0 Mbps * 24.0 Mbps * 36.0 Mbps * 48.0 Mbps * 54.0 Mbps max # scan SSIDs: 4 max scan IEs length: 2257 bytes Coverage class: 0 (up to 0m) Supported Ciphers: * WEP40 (00-0f-ac:1) * WEP104 (00-0f-ac:5) * TKIP (00-0f-ac:2) * CCMP (00-0f-ac:4) Available Antennas: TX 0 RX 0 Supported interface modes: * IBSS * managed * AP * AP/VLAN * WDS * monitor * mesh point software interface modes (can always be added): * AP/VLAN * monitor valid interface combinations: * #{ AP, mesh point } <= 8, total <= 8, #channels <= 1 Supported commands: * new_interface * set_interface * new_key * new_beacon * new_station * new_mpath * set_mesh_params * set_bss * authenticate * associate * deauthenticate * disassociate * join_ibss * join_mesh * set_tx_bitrate_mask * action * frame_wait_cancel * set_wiphy_netns * set_channel * set_wds_peer * Unknown command (84) * Unknown command (87) * Unknown command (85) * Unknown command (89) * Unknown command (92) * testmode * connect * disconnect Supported TX frame types: * IBSS: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0 * managed: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0 * AP: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0 * AP/VLAN: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0 * mesh point: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0 * P2P-client: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0 * P2P-GO: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0 * Unknown mode (10): 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0 Supported RX frame types: * IBSS: 0x40 0xb0 0xc0 0xd0 * managed: 0x40 0xd0 * AP: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0 * AP/VLAN: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0 * mesh point: 0xb0 0xc0 0xd0 * P2P-client: 0x40 0xd0 * P2P-GO: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0 * Unknown mode (10): 0x40 0xd0 Device supports RSN-IBSS. HT Capability overrides: * MCS: ff ff ff ff ff ff ff ff ff ff * maximum A-MSDU length * supported channel width * short GI for 40 MHz * max A-MPDU length exponent * min MPDU start spacing Device supports TX status socket option. Device supports HT-IBSS. -- Tuomas ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: PROBLEM: skb_push called from rt2x00 panics occasionally 2014-01-30 12:33 ` PROBLEM: skb_push called from rt2x00 panics occasionally Tuomas Räsänen @ 2014-01-30 19:39 ` Stanislaw Gruszka 0 siblings, 0 replies; 2+ messages in thread From: Stanislaw Gruszka @ 2014-01-30 19:39 UTC (permalink / raw) To: Tuomas Räsänen Cc: Ivo van Doorn, Gertjan van Wingerde, Helmut Schaa, John W. Linville, linux-wireless, users, tuomasjjrasanen, Veli-Matti Lintu On Thu, Jan 30, 2014 at 12:33:42PM +0000, Tuomas Räsänen wrote: > ================================================= > skb_push called from rt2x00 panics occasionally > ================================================= > > We have been experiencing occasional skb_push panics with rt2x00 driver > throughout the stable v3.10 -series. Problems occur with hosts acting as > accesspoints, managed by hostapd 2.0. Some hosts panic reportedly > several times per week, some almost never. All hosts have identical > kernels and WiFi adapters. > > We have not been able to reproduce panics in a controlled manner. > > I'd be very happy to get some advice how to proceed in debugging and fixing > this problem and even better, to understand the whole issue > thoroughly. Unfortunately, all I know now is that the skb headroom is > not big enough for the frame the AP is trying to transmit, right? > Hopefully someone can shed some light on this problem. Yes, is possible that we have no headroom for frame retransmitted several times, but I do not see bug in code for that so far. We remove and add again l2 pad for retransmit frame, that should not utilize more headroom than for first frame transmission (as long mac80211 does not increase header length, but that seems to be not possible and sensible). For know you can try to increase headroom like on below patch or use module with nohwcrypt=1. Please check if any of that stops panics or just make it less reproducible. You can also configure kdump to dump memory to see how skb looks when kernel crashes. Stanislaw diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h index e4ba2ce..50fc3e7 100644 --- a/drivers/net/wireless/rt2x00/rt2x00.h +++ b/drivers/net/wireless/rt2x00/rt2x00.h @@ -115,7 +115,7 @@ * Constants for extra TX headroom for alignment purposes. */ #define RT2X00_ALIGN_SIZE 4 /* Only whole frame needs alignment */ -#define RT2X00_L2PAD_SIZE 8 /* Both header & payload need alignment */ +#define RT2X00_L2PAD_SIZE 12 /* Both header & payload need alignment */ /* * Standard timing and size defines. ^ permalink raw reply related [flat|nested] 2+ messages in thread
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2014-01-30 12:33 ` PROBLEM: skb_push called from rt2x00 panics occasionally Tuomas Räsänen
2014-01-30 19:39 ` Stanislaw Gruszka
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