Bug 114791

Summary: Kernel WARNING at net/core/skbuff.c:693 skb_release_head_state+0x64/0x78()
Product: Networking Reporter: henri.roosen
Component: Netfilter/IptablesAssignee: networking_netfilter-iptables (networking_netfilter-iptables)
Status: NEW ---    
Severity: normal    
Priority: P1    
Hardware: ARM   
OS: Linux   
Kernel Version: 4.1.19 Subsystem:
Regression: No Bisected commit-id:

Description henri.roosen 2016-03-16 11:51:52 UTC 
This kernel warning is triggered when repeating opening/closing a socketcan test application in userspace:

[  192.835652] ------------[ cut here ]------------
[  192.840306] WARNING: CPU: 0 PID: 0 at net/core/skbuff.c:693 skb_release_head_state+0x64/0x78()
[  192.848922] Modules linked in:
[  192.852004] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.19-ge-16.02+-general-1-00316-g716807c #378
[  192.861140] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[  192.867671] Backtrace:
[  192.870159] [<c001203c>] (dump_backtrace) from [<c0012248>] (show_stack+0x18/0x1c)
[  192.877732]  r6:200f0193 r5:ffffffff r4:00000000 r3:00200000
[  192.883477] [<c0012230>] (show_stack) from [<c049d20c>] (dump_stack+0x80/0xa0)
[  192.890714] [<c049d18c>] (dump_stack) from [<c0029f54>] (warn_slowpath_common+0x8c/0xb8)
[  192.898808]  r6:c0665fa5 r5:00000009 r4:00000000 r3:c0716000
[  192.904542] [<c0029ec8>] (warn_slowpath_common) from [<c002a024>] (warn_slowpath_null+0x24/0x2c)
[  192.913330]  r8:c071859c r7:c0714c00 r6:c0717d80 r5:ee1bac70 r4:ed46c4c0
[  192.920122] [<c002a000>] (warn_slowpath_null) from [<c03f8398>] (skb_release_head_state+0x64/0x78)
[  192.929092] [<c03f8334>] (skb_release_head_state) from [<c03f84e0>] (skb_release_all+0x14/0x2c)
[  192.937793]  r4:ed46c4c0 r3:00000001
[  192.941411] [<c03f84cc>] (skb_release_all) from [<c03f850c>] (__kfree_skb+0x14/0x94)
[  192.949157]  r4:ed46c4c0 r3:00000001
[  192.952775] [<c03f84f8>] (__kfree_skb) from [<c03f85e4>] (kfree_skb+0x58/0x5c)
[  192.960001]  r4:ed46c4c0 r3:00000001
[  192.963625] [<c03f858c>] (kfree_skb) from [<c04045e0>] (enqueue_to_backlog+0x170/0x238)
[  192.971640] [<c0404470>] (enqueue_to_backlog) from [<c0404718>] (netif_rx_internal+0x70/0x114)
[  192.980255]  r10:c0743129 r9:edd84f40 r8:00000200 r7:00000000 r6:c0717d80 r5:00000000
[  192.988168]  r4:ed46c4c0
[  192.990728] [<c04046a8>] (netif_rx_internal) from [<c04047cc>] (netif_rx+0x10/0x14)
[  192.998387]  r6:00000008 r5:00000000 r4:ed567000
[  193.003069] [<c04047bc>] (netif_rx) from [<c03110b0>] (can_get_echo_skb+0x40/0x54)
[  193.010652] [<c0311070>] (can_get_echo_skb) from [<c0312768>] (flexcan_irq+0x158/0x1c8)
[  193.018659]  r6:0000cd98 r5:ed567000 r4:f01b8000 r3:00000000
[  193.024398] [<c0312610>] (flexcan_irq) from [<c0061f44>] (handle_irq_event_percpu+0x38/0x130)
[  193.032925]  r8:edc06000 r7:00000000 r6:00000000 r5:0000001c r4:ed0ae440 r3:c0312610
[  193.040760] [<c0061f0c>] (handle_irq_event_percpu) from [<c0062080>] (handle_irq_event+0x44/0x64)
[  193.049635]  r10:c0717ee0 r9:00000001 r8:edc06000 r7:00000000 r6:ed0ae440 r5:edd84fa0
[  193.057549]  r4:edd84f40
[  193.060116] [<c006203c>] (handle_irq_event) from [<c0065160>] (handle_fasteoi_irq+0xbc/0x138)
[  193.068644]  r6:edd84fa0 r5:c071dbf0 r4:edd84f40 r3:00000000
[  193.074380] [<c00650a4>] (handle_fasteoi_irq) from [<c006163c>] (generic_handle_irq+0x28/0x38)
[  193.082995]  r6:c07129ac r5:c07129ac r4:0000001c r3:c00650a4
[  193.088729] [<c0061614>] (generic_handle_irq) from [<c006194c>] (__handle_domain_irq+0xa8/0xe8)
[  193.097430]  r4:00000000 r3:0000012f
[  193.101047] [<c00618a4>] (__handle_domain_irq) from [<c00093dc>] (gic_handle_irq+0x40/0x64)
[  193.109401]  r10:00000000 r9:0000002c r8:e55c15b3 r7:c0717f14 r6:c0718700 r5:c0717ee0
[  193.117314]  r4:f4000100 r3:c0717ee0
[  193.120929] [<c000939c>] (gic_handle_irq) from [<c0012d00>] (__irq_svc+0x40/0x74)
[  193.128419] Exception stack(0xc0717ee0 to 0xc0717f28)
[  193.133481] 7ee0: c0717f28 0000002c c2135e9d 0000002c e5698eeb 0000002c 00000000 ee1b9a68
[  193.141668] 7f00: e55c15b3 0000002c 00000000 c0717f5c 00000009 c0717f28 c007580c c0389d60
[  193.149850] 7f20: 600f0013 ffffffff
[  193.153342]  r6:ffffffff r5:600f0013 r4:c0389d60 r3:c007580c
[  193.159080] [<c0389c94>] (cpuidle_enter_state) from [<c0389e8c>] (cpuidle_enter+0x1c/0x20)
[  193.167347]  r10:c0713a60 r9:c0711284 r8:c0717f70 r7:c0714300 r6:c071d890 r5:c0716000
[  193.175259]  r4:ee1b9a68
[  193.177828] [<c0389e70>] (cpuidle_enter) from [<c0058590>] (cpu_startup_entry+0x200/0x2d8)
[  193.186106] [<c0058390>] (cpu_startup_entry) from [<c0499dc8>] (rest_init+0x7c/0x94)
[  193.193852]  r7:ffffffff
[  193.196424] [<c0499d4c>] (rest_init) from [<c06a3c24>] (start_kernel+0x2e0/0x338)
[  193.203910]  r4:00000000 r3:c0716000
[  193.207530] [<c06a3944>] (start_kernel) from [<1000807c>] (0x1000807c)
[  193.214063] ---[ end trace db15eacd7eb444c8 ]---
[  193.218686] ------------[ cut here ]------------
[  193.223316] WARNING: CPU: 0 PID: 0 at net/core/skbuff.c:693 skb_release_head_state+0x64/0x78()
[  193.231930] Modules linked in:
[  193.235008] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W       4.1.19-ge-16.02+-general-1-00316-g716807c #378
[  193.245360] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[  193.251890] Backtrace:
[  193.254367] [<c001203c>] (dump_backtrace) from [<c0012248>] (show_stack+0x18/0x1c)
[  193.261940]  r6:200f0193 r5:ffffffff r4:00000000 r3:00200000
[  193.267678] [<c0012230>] (show_stack) from [<c049d20c>] (dump_stack+0x80/0xa0)
[  193.274913] [<c049d18c>] (dump_stack) from [<c0029f54>] (warn_slowpath_common+0x8c/0xb8)
[  193.283006]  r6:c0665fa5 r5:00000009 r4:00000000 r3:c0716000
[  193.288740] [<c0029ec8>] (warn_slowpath_common) from [<c002a024>] (warn_slowpath_null+0x24/0x2c)
[  193.297528]  r8:c071859c r7:c0714c00 r6:c0717d80 r5:ed1516ac r4:ededaf40
[  193.304321] [<c002a000>] (warn_slowpath_null) from [<c03f8398>] (skb_release_head_state+0x64/0x78)
[  193.313292] [<c03f8334>] (skb_release_head_state) from [<c03f84e0>] (skb_release_all+0x14/0x2c)
[  193.321993]  r4:ededaf40 r3:00000001
[  193.325611] [<c03f84cc>] (skb_release_all) from [<c03f850c>] (__kfree_skb+0x14/0x94)
[  193.333357]  r4:ededaf40 r3:00000001
[  193.336975] [<c03f84f8>] (__kfree_skb) from [<c03f85e4>] (kfree_skb+0x58/0x5c)
[  193.344200]  r4:ed151654 r3:00000001
[  193.347821] [<c03f858c>] (kfree_skb) from [<c03fa43c>] (skb_queue_purge+0x24/0x2c)
[  193.355409] [<c03fa418>] (skb_queue_purge) from [<c047cb60>] (can_sock_destruct+0x14/0x18)
[  193.363676]  r4:ed151600 r3:c047cb4c
[  193.367295] [<c047cb4c>] (can_sock_destruct) from [<c03f6224>] (__sk_free+0x20/0xe4)
[  193.375050] [<c03f6204>] (__sk_free) from [<c03f691c>] (sock_wfree+0x80/0x84)
[  193.382189]  r5:ed1516ac r4:ed151600
[  193.385806] [<c03f689c>] (sock_wfree) from [<c03f83a4>] (skb_release_head_state+0x70/0x78)
[  193.394074]  r5:ee1bac70 r4:ed46c4c0
[  193.397692] [<c03f8334>] (skb_release_head_state) from [<c03f84e0>] (skb_release_all+0x14/0x2c)
[  193.406393]  r4:ed46c4c0 r3:00000001
[  193.410011] [<c03f84cc>] (skb_release_all) from [<c03f850c>] (__kfree_skb+0x14/0x94)
[  193.417757]  r4:ed46c4c0 r3:00000001
[  193.421374] [<c03f84f8>] (__kfree_skb) from [<c03f85e4>] (kfree_skb+0x58/0x5c)
[  193.428599]  r4:ed46c4c0 r3:00000001
[  193.432218] [<c03f858c>] (kfree_skb) from [<c04045e0>] (enqueue_to_backlog+0x170/0x238)
[  193.440235] [<c0404470>] (enqueue_to_backlog) from [<c0404718>] (netif_rx_internal+0x70/0x114)
[  193.448849]  r10:c0743129 r9:edd84f40 r8:00000200 r7:00000000 r6:c0717d80 r5:00000000
[  193.456761]  r4:ed46c4c0
[  193.459320] [<c04046a8>] (netif_rx_internal) from [<c04047cc>] (netif_rx+0x10/0x14)
[  193.466979]  r6:00000008 r5:00000000 r4:ed567000
[  193.471655] [<c04047bc>] (netif_rx) from [<c03110b0>] (can_get_echo_skb+0x40/0x54)
[  193.479236] [<c0311070>] (can_get_echo_skb) from [<c0312768>] (flexcan_irq+0x158/0x1c8)
[  193.487242]  r6:0000cd98 r5:ed567000 r4:f01b8000 r3:00000000
[  193.492979] [<c0312610>] (flexcan_irq) from [<c0061f44>] (handle_irq_event_percpu+0x38/0x130)
[  193.501506]  r8:edc06000 r7:00000000 r6:00000000 r5:0000001c r4:ed0ae440 r3:c0312610
[  193.509341] [<c0061f0c>] (handle_irq_event_percpu) from [<c0062080>] (handle_irq_event+0x44/0x64)
[  193.518216]  r10:c0717ee0 r9:00000001 r8:edc06000 r7:00000000 r6:ed0ae440 r5:edd84fa0
[  193.526128]  r4:edd84f40
[  193.528691] [<c006203c>] (handle_irq_event) from [<c0065160>] (handle_fasteoi_irq+0xbc/0x138)
[  193.537218]  r6:edd84fa0 r5:c071dbf0 r4:edd84f40 r3:00000000
[  193.542953] [<c00650a4>] (handle_fasteoi_irq) from [<c006163c>] (generic_handle_irq+0x28/0x38)
[  193.551567]  r6:c07129ac r5:c07129ac r4:0000001c r3:c00650a4
[  193.557301] [<c0061614>] (generic_handle_irq) from [<c006194c>] (__handle_domain_irq+0xa8/0xe8)
[  193.566002]  r4:00000000 r3:0000012f
[  193.569620] [<c00618a4>] (__handle_domain_irq) from [<c00093dc>] (gic_handle_irq+0x40/0x64)
[  193.577974]  r10:00000000 r9:0000002c r8:e55c15b3 r7:c0717f14 r6:c0718700 r5:c0717ee0
[  193.585887]  r4:f4000100 r3:c0717ee0
[  193.589502] [<c000939c>] (gic_handle_irq) from [<c0012d00>] (__irq_svc+0x40/0x74)
[  193.596990] Exception stack(0xc0717ee0 to 0xc0717f28)
[  193.602051] 7ee0: c0717f28 0000002c c2135e9d 0000002c e5698eeb 0000002c 00000000 ee1b9a68
[  193.610238] 7f00: e55c15b3 0000002c 00000000 c0717f5c 00000009 c0717f28 c007580c c0389d60
[  193.618419] 7f20: 600f0013 ffffffff
[  193.621912]  r6:ffffffff r5:600f0013 r4:c0389d60 r3:c007580c
[  193.627645] [<c0389c94>] (cpuidle_enter_state) from [<c0389e8c>] (cpuidle_enter+0x1c/0x20)
[  193.635912]  r10:c0713a60 r9:c0711284 r8:c0717f70 r7:c0714300 r6:c071d890 r5:c0716000
[  193.643825]  r4:ee1b9a68
[  193.646387] [<c0389e70>] (cpuidle_enter) from [<c0058590>] (cpu_startup_entry+0x200/0x2d8)
[  193.654664] [<c0058390>] (cpu_startup_entry) from [<c0499dc8>] (rest_init+0x7c/0x94)
[  193.662410]  r7:ffffffff
[  193.664977] [<c0499d4c>] (rest_init) from [<c06a3c24>] (start_kernel+0x2e0/0x338)
[  193.672463]  r4:00000000 r3:c0716000
[  193.676079] [<c06a3944>] (start_kernel) from [<1000807c>] (0x1000807c)
[  193.682613] ---[ end trace db15eacd7eb444c9 ]---
Comment 1 henri.roosen 2016-03-16 14:41:48 UTC 
Further investigations: the can0 interface is brought down by some other process, which seems to trigger the kernel Warning. The following script easily reproduces the problem on a FreeScale i.MX6 system:

#!/bin/sh
while true; do
        ifconfig can0 up
        cangen can0 -g 4 &
        can_pid=$!
        sleep 1
        ifconfig can0 down
        kill -9 $can_pid
        sleep 1
done