Re: [lkp-robot] [ipv6] 2b760fcf5c: WARNING:suspicious_RCU_usage

2017-10-13 Thread Eric Dumazet 
On Thu, Oct 12, 2017 at 10:09 PM, Wei Wang  wrote:
>
> This warning should be fixed by later commit 66f5d6ce53e6 ("ipv6:
> replace rwlock with rcu and spinlock in fib6_table").
> But by this commit, rcu is not yet used in ip6_pol_route(). (Sorry
> that I missed this earlier.) Not sure what to do here to fix this
> particular warning for this commit.

Hi Wei

There is nothing special to be done, if the current tree is all good.

Such a major patch series being done without a single temp 'bug' would
have been quite a challenge.

Thanks !

Re: [lkp-robot] [ipv6] 2b760fcf5c: WARNING:suspicious_RCU_usage

2017-10-13 Thread Eric Dumazet 
On Thu, Oct 12, 2017 at 10:09 PM, Wei Wang  wrote:
>
> This warning should be fixed by later commit 66f5d6ce53e6 ("ipv6:
> replace rwlock with rcu and spinlock in fib6_table").
> But by this commit, rcu is not yet used in ip6_pol_route(). (Sorry
> that I missed this earlier.) Not sure what to do here to fix this
> particular warning for this commit.

Hi Wei

There is nothing special to be done, if the current tree is all good.

Such a major patch series being done without a single temp 'bug' would
have been quite a challenge.

Thanks !

Re: [lkp-robot] [ipv6] 2b760fcf5c: WARNING:suspicious_RCU_usage

2017-10-12 Thread Wei Wang 
On Thu, Oct 12, 2017 at 7:03 PM, kernel test robot
 wrote:
>
> FYI, we noticed the following commit (built with gcc-6):
>
> commit: 2b760fcf5cfb34e8610df56d83745b2b74ae1379 ("ipv6: hook up exception 
> table to store dst cache")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> in testcase: boot
>
> on test machine: qemu-system-x86_64 -enable-kvm -m 420M
>
> caused below changes (please refer to attached dmesg/kmsg for entire 
> log/backtrace):
>
>
> +---+++
> |   | 38fbcc | 
> 2b760fcf5c |
> +---+++
> | boot_successes| 6  | 2  
> |
> | boot_failures | 2  | 32 
> |
> | BUG:kernel_hang_in_test_stage | 2  |
> |
> | WARNING:suspicious_RCU_usage  | 0  | 32 
> |
> | net/ipv6/route.c:#suspicious_rcu_dereference_check()usage | 0  | 32 
> |
> | WARNING:at_net/ipv6/route.c:#__rt6_find_exception_rcu | 0  | 32 
> |
> +---+++
>
>

This warning should be fixed by later commit 66f5d6ce53e6 ("ipv6:
replace rwlock with rcu and spinlock in fib6_table").
But by this commit, rcu is not yet used in ip6_pol_route(). (Sorry
that I missed this earlier.) Not sure what to do here to fix this
particular warning for this commit.

> [   19.842463] WARNING: suspicious RCU usage
> [   19.843540] 4.14.0-rc3-00907-g2b760fc #58 Not tainted
> [   19.844776] -
> [   19.845854] net/ipv6/route.c:1355 suspicious rcu_dereference_check() usage!
> [   19.847961]
> [   19.847961] other info that might help us debug this:
> [   19.847961]
> [   19.850409]
> [   19.850409] rcu_scheduler_active = 2, debug_locks = 1
> [   19.852220] 2 locks held by odhcpd/3695:
> [   19.853285]  #0:  (sk_lock-AF_INET6){+.+.}, at: [] 
> ip6_datagram_connect+0x1d/0x3f
> [   19.855480]  #1:  (>tb6_lock){++--}, at: [] 
> ip6_pol_route+0x51/0x80c
> [   19.857583]
> [   19.857583] stack backtrace:
> [   19.859115] CPU: 0 PID: 3695 Comm: odhcpd Not tainted 
> 4.14.0-rc3-00907-g2b760fc #58
> [   19.861087] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
> 1.10.2-1 04/01/2014
> [   19.863123] Call Trace:
> [   19.863963]  dump_stack+0x86/0xc0
> [   19.864926]  lockdep_rcu_suspicious+0xea/0xf3
> [   19.866031]  rt6_find_cached_rt+0x51/0x84
> [   19.867173]  ip6_pol_route+0x21c/0x80c
> [   19.868199]  ip6_pol_route_output+0x16/0x18
> [   19.869287]  fib6_rule_lookup+0x1e/0x55
> [   19.870307]  ip6_route_output_flags+0xb6/0xc2
> [   19.871410]  ip6_dst_lookup_tail+0x4f/0x194
> [   19.872500]  ip6_dst_lookup_flow+0x38/0x78
> [   19.873562]  ip6_datagram_dst_update+0x254/0x482
> [   19.874690]  ? save_stack_trace+0x1b/0x1d
> [   19.875760]  __ip6_datagram_connect+0x20e/0x299
> [   19.876881]  ? __ip6_datagram_connect+0x20e/0x299
> [   19.878054]  ip6_datagram_connect+0x2b/0x3f
> [   19.879160]  ip6_datagram_connect_v6_only+0x14/0x1c
> [   19.880348]  inet_dgram_connect+0x49/0x68
> [   19.881424]  SyS_connect+0x74/0xa1
> [   19.882424]  ? __might_fault+0x7e/0x84
> [   19.883495]  ? _copy_from_user+0x61/0x82
> [   19.884531]  compat_SyS_socketcall+0xfb/0x1fd
> [   19.885644]  ? trace_hardirqs_on_caller+0x17b/0x197
> [   19.886868]  do_int80_syscall_32+0x66/0x15a
> [   19.887979]  entry_INT80_compat+0x32/0x50
> [   19.889037] RIP: 0023:0xf7f5e384
> [   19.889985] RSP: 002b:ffc94db8 EFLAGS: 0296 ORIG_RAX: 
> 0066
> [   19.891958] RAX: ffda RBX: 0003 RCX: 
> ffc94dc8
> [   19.893475] RDX: f7fa4000 RSI: ffc94dc8 RDI: 
> ffc94ee0
> [   19.894946] RBP: ffc94e28 R08:  R09: 
> 
> [   19.896454] R10:  R11:  R12: 
> 
> [   19.897968] R13:  R14:  R15: 
> 
> [   19.899594] [ cut here ]
> [   19.900775] WARNING: CPU: 0 PID: 3695 at net/ipv6/route.c:1208 
> __rt6_find_exception_rcu+0x1b/0x7b
> [   19.903220] Modules linked in:
> [   19.904172] CPU: 0 PID: 3695 Comm: odhcpd Not tainted 
> 4.14.0-rc3-00907-g2b760fc #58
> [   19.906147] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
> 1.10.2-1 04/01/2014
> [   19.908263] task: a024549f0040 task.stack: aee58081
> [   19.909644] RIP: 0010:__rt6_find_exception_rcu+0x1b/0x7b
> [   19.910973] RSP: :aee580813af0 EFLAGS: 00010246
> [   19.912231] RAX:  RBX: aee580813cf0 RCX: 
> 0001
> [   19.913783] RDX:  RSI:

Re: [lkp-robot] [ipv6] 2b760fcf5c: WARNING:suspicious_RCU_usage

2017-10-12 Thread Wei Wang 
On Thu, Oct 12, 2017 at 7:03 PM, kernel test robot
 wrote:
>
> FYI, we noticed the following commit (built with gcc-6):
>
> commit: 2b760fcf5cfb34e8610df56d83745b2b74ae1379 ("ipv6: hook up exception 
> table to store dst cache")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> in testcase: boot
>
> on test machine: qemu-system-x86_64 -enable-kvm -m 420M
>
> caused below changes (please refer to attached dmesg/kmsg for entire 
> log/backtrace):
>
>
> +---+++
> |   | 38fbcc | 
> 2b760fcf5c |
> +---+++
> | boot_successes| 6  | 2  
> |
> | boot_failures | 2  | 32 
> |
> | BUG:kernel_hang_in_test_stage | 2  |
> |
> | WARNING:suspicious_RCU_usage  | 0  | 32 
> |
> | net/ipv6/route.c:#suspicious_rcu_dereference_check()usage | 0  | 32 
> |
> | WARNING:at_net/ipv6/route.c:#__rt6_find_exception_rcu | 0  | 32 
> |
> +---+++
>
>

This warning should be fixed by later commit 66f5d6ce53e6 ("ipv6:
replace rwlock with rcu and spinlock in fib6_table").
But by this commit, rcu is not yet used in ip6_pol_route(). (Sorry
that I missed this earlier.) Not sure what to do here to fix this
particular warning for this commit.

> [   19.842463] WARNING: suspicious RCU usage
> [   19.843540] 4.14.0-rc3-00907-g2b760fc #58 Not tainted
> [   19.844776] -
> [   19.845854] net/ipv6/route.c:1355 suspicious rcu_dereference_check() usage!
> [   19.847961]
> [   19.847961] other info that might help us debug this:
> [   19.847961]
> [   19.850409]
> [   19.850409] rcu_scheduler_active = 2, debug_locks = 1
> [   19.852220] 2 locks held by odhcpd/3695:
> [   19.853285]  #0:  (sk_lock-AF_INET6){+.+.}, at: [] 
> ip6_datagram_connect+0x1d/0x3f
> [   19.855480]  #1:  (>tb6_lock){++--}, at: [] 
> ip6_pol_route+0x51/0x80c
> [   19.857583]
> [   19.857583] stack backtrace:
> [   19.859115] CPU: 0 PID: 3695 Comm: odhcpd Not tainted 
> 4.14.0-rc3-00907-g2b760fc #58
> [   19.861087] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
> 1.10.2-1 04/01/2014
> [   19.863123] Call Trace:
> [   19.863963]  dump_stack+0x86/0xc0
> [   19.864926]  lockdep_rcu_suspicious+0xea/0xf3
> [   19.866031]  rt6_find_cached_rt+0x51/0x84
> [   19.867173]  ip6_pol_route+0x21c/0x80c
> [   19.868199]  ip6_pol_route_output+0x16/0x18
> [   19.869287]  fib6_rule_lookup+0x1e/0x55
> [   19.870307]  ip6_route_output_flags+0xb6/0xc2
> [   19.871410]  ip6_dst_lookup_tail+0x4f/0x194
> [   19.872500]  ip6_dst_lookup_flow+0x38/0x78
> [   19.873562]  ip6_datagram_dst_update+0x254/0x482
> [   19.874690]  ? save_stack_trace+0x1b/0x1d
> [   19.875760]  __ip6_datagram_connect+0x20e/0x299
> [   19.876881]  ? __ip6_datagram_connect+0x20e/0x299
> [   19.878054]  ip6_datagram_connect+0x2b/0x3f
> [   19.879160]  ip6_datagram_connect_v6_only+0x14/0x1c
> [   19.880348]  inet_dgram_connect+0x49/0x68
> [   19.881424]  SyS_connect+0x74/0xa1
> [   19.882424]  ? __might_fault+0x7e/0x84
> [   19.883495]  ? _copy_from_user+0x61/0x82
> [   19.884531]  compat_SyS_socketcall+0xfb/0x1fd
> [   19.885644]  ? trace_hardirqs_on_caller+0x17b/0x197
> [   19.886868]  do_int80_syscall_32+0x66/0x15a
> [   19.887979]  entry_INT80_compat+0x32/0x50
> [   19.889037] RIP: 0023:0xf7f5e384
> [   19.889985] RSP: 002b:ffc94db8 EFLAGS: 0296 ORIG_RAX: 
> 0066
> [   19.891958] RAX: ffda RBX: 0003 RCX: 
> ffc94dc8
> [   19.893475] RDX: f7fa4000 RSI: ffc94dc8 RDI: 
> ffc94ee0
> [   19.894946] RBP: ffc94e28 R08:  R09: 
> 
> [   19.896454] R10:  R11:  R12: 
> 
> [   19.897968] R13:  R14:  R15: 
> 
> [   19.899594] [ cut here ]
> [   19.900775] WARNING: CPU: 0 PID: 3695 at net/ipv6/route.c:1208 
> __rt6_find_exception_rcu+0x1b/0x7b
> [   19.903220] Modules linked in:
> [   19.904172] CPU: 0 PID: 3695 Comm: odhcpd Not tainted 
> 4.14.0-rc3-00907-g2b760fc #58
> [   19.906147] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
> 1.10.2-1 04/01/2014
> [   19.908263] task: a024549f0040 task.stack: aee58081
> [   19.909644] RIP: 0010:__rt6_find_exception_rcu+0x1b/0x7b
> [   19.910973] RSP: :aee580813af0 EFLAGS: 00010246
> [   19.912231] RAX:  RBX: aee580813cf0 RCX: 
> 0001
> [   19.913783] RDX:  RSI: 9b47f900 RDI: 
>