* net: rcu warnings in ip6fl_get_first
@ 2013-02-07 19:32 Sasha Levin
2013-02-08 1:37 ` Cong Wang
2013-02-08 1:38 ` Cong Wang
0 siblings, 2 replies; 5+ messages in thread
From: Sasha Levin @ 2013-02-07 19:32 UTC (permalink / raw)
To: David S. Miller, yoshfuji
Cc: Dave Jones, netdev, linux-kernel@vger.kernel.org
Hi guys,
I got the following while fuzzing with trinity inside a KVM tools guest:
[ 51.680236] ===============================
[ 51.681914] [ INFO: suspicious RCU usage. ]
[ 51.683610] 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276 Tainted: G W
[ 51.686703] -------------------------------
[ 51.688281] net/ipv6/ip6_flowlabel.c:671 suspicious rcu_dereference_check() usage!
[ 51.691345]
[ 51.691345] other info that might help us debug this:
[ 51.691345]
[ 51.694479]
[ 51.694479] rcu_scheduler_active = 1, debug_locks = 1
[ 51.697650] 2 locks held by trinity/7421:
[ 51.701271] #0: (&p->lock){+.+.+.}, at: [<ffffffff812b049a>] seq_read+0x3a/0x3d0
[ 51.704292] #1: (rcu_read_lock_bh){.+....}, at: [<ffffffff8397cde0>] ip6fl_seq_start+0x0/0xe0
[ 51.707845]
[ 51.707845] stack backtrace:
[ 51.709678] Pid: 7421, comm: trinity Tainted: G W 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276
[ 51.713495] Call Trace:
[ 51.714370] [<ffffffff81181fdb>] lockdep_rcu_suspicious+0x10b/0x120
[ 51.716560] [<ffffffff8397caca>] ip6fl_get_first+0x8a/0x140
[ 51.718755] [<ffffffff8397cdb7>] ip6fl_seq_next+0x17/0x40
[ 51.720963] [<ffffffff812b0711>] seq_read+0x2b1/0x3d0
[ 51.723056] [<ffffffff812b0460>] ? seq_lseek+0x110/0x110
[ 51.725238] [<ffffffff812f9c0c>] proc_reg_read+0x9c/0xd0
[ 51.727266] [<ffffffff812f9b70>] ? proc_reg_write+0xd0/0xd0
[ 51.729337] [<ffffffff8128b2eb>] do_loop_readv_writev+0x4b/0x90
[ 51.731846] [<ffffffff8128b566>] do_readv_writev+0xf6/0x1d0
[ 51.734092] [<ffffffff8128b6de>] vfs_readv+0x3e/0x60
[ 51.736015] [<ffffffff8128b750>] sys_readv+0x50/0xd0
[ 51.737930] [<ffffffff83d73d98>] tracesys+0xe1/0xe6
This is the result of commit "ipv6 flowlabel: Convert hash list to RCU." which
mixes between regular and _bh() locking.
Thanks,
Sasha
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: net: rcu warnings in ip6fl_get_first
2013-02-07 19:32 net: rcu warnings in ip6fl_get_first Sasha Levin
@ 2013-02-08 1:37 ` Cong Wang
2013-02-08 1:38 ` Cong Wang
1 sibling, 0 replies; 5+ messages in thread
From: Cong Wang @ 2013-02-08 1:37 UTC (permalink / raw)
To: linux-kernel; +Cc: netdev
["Followup-To:" header set to gmane.linux.network.]
On Thu, 07 Feb 2013 at 19:32 GMT, Sasha Levin <sasha.levin@oracle.com> wrote:
> Hi guys,
>
> I got the following while fuzzing with trinity inside a KVM tools guest:
>
> [ 51.680236] ===============================
> [ 51.681914] [ INFO: suspicious RCU usage. ]
> [ 51.683610] 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276 Tainted: G W
> [ 51.686703] -------------------------------
> [ 51.688281] net/ipv6/ip6_flowlabel.c:671 suspicious rcu_dereference_check() usage!
> [ 51.691345]
> [ 51.691345] other info that might help us debug this:
> [ 51.691345]
> [ 51.694479]
> [ 51.694479] rcu_scheduler_active = 1, debug_locks = 1
> [ 51.697650] 2 locks held by trinity/7421:
> [ 51.701271] #0: (&p->lock){+.+.+.}, at: [<ffffffff812b049a>] seq_read+0x3a/0x3d0
> [ 51.704292] #1: (rcu_read_lock_bh){.+....}, at: [<ffffffff8397cde0>] ip6fl_seq_start+0x0/0xe0
> [ 51.707845]
> [ 51.707845] stack backtrace:
> [ 51.709678] Pid: 7421, comm: trinity Tainted: G W 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276
> [ 51.713495] Call Trace:
> [ 51.714370] [<ffffffff81181fdb>] lockdep_rcu_suspicious+0x10b/0x120
> [ 51.716560] [<ffffffff8397caca>] ip6fl_get_first+0x8a/0x140
> [ 51.718755] [<ffffffff8397cdb7>] ip6fl_seq_next+0x17/0x40
> [ 51.720963] [<ffffffff812b0711>] seq_read+0x2b1/0x3d0
> [ 51.723056] [<ffffffff812b0460>] ? seq_lseek+0x110/0x110
> [ 51.725238] [<ffffffff812f9c0c>] proc_reg_read+0x9c/0xd0
> [ 51.727266] [<ffffffff812f9b70>] ? proc_reg_write+0xd0/0xd0
> [ 51.729337] [<ffffffff8128b2eb>] do_loop_readv_writev+0x4b/0x90
> [ 51.731846] [<ffffffff8128b566>] do_readv_writev+0xf6/0x1d0
> [ 51.734092] [<ffffffff8128b6de>] vfs_readv+0x3e/0x60
> [ 51.736015] [<ffffffff8128b750>] sys_readv+0x50/0xd0
> [ 51.737930] [<ffffffff83d73d98>] tracesys+0xe1/0xe6
>
> This is the result of commit "ipv6 flowlabel: Convert hash list to RCU." which
> mixes between regular and _bh() locking.
>
>
> Thanks,
> Sasha
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: net: rcu warnings in ip6fl_get_first
2013-02-07 19:32 net: rcu warnings in ip6fl_get_first Sasha Levin
2013-02-08 1:37 ` Cong Wang
@ 2013-02-08 1:38 ` Cong Wang
2013-02-08 3:54 ` Sasha Levin
2013-02-08 19:19 ` Paul E. McKenney
1 sibling, 2 replies; 5+ messages in thread
From: Cong Wang @ 2013-02-08 1:38 UTC (permalink / raw)
To: netdev; +Cc: linux-kernel
On Thu, 07 Feb 2013 at 19:32 GMT, Sasha Levin <sasha.levin@oracle.com> wrote:
> Hi guys,
>
> I got the following while fuzzing with trinity inside a KVM tools guest:
>
> [ 51.680236] ===============================
> [ 51.681914] [ INFO: suspicious RCU usage. ]
> [ 51.683610] 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276 Tainted: G W
> [ 51.686703] -------------------------------
> [ 51.688281] net/ipv6/ip6_flowlabel.c:671 suspicious rcu_dereference_check() usage!
> [ 51.691345]
It should use rcu_dereference_bh()...
diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
index ea42bf4..c50080f 100644
--- a/net/ipv6/ip6_flowlabel.c
+++ b/net/ipv6/ip6_flowlabel.c
@@ -65,13 +65,13 @@ static DEFINE_SPINLOCK(ip6_fl_lock);
static DEFINE_SPINLOCK(ip6_sk_fl_lock);
#define for_each_fl_rcu(hash, fl) \
- for (fl = rcu_dereference(fl_ht[(hash)]); \
+ for (fl = rcu_dereference_bh(fl_ht[(hash)]); \
fl != NULL; \
- fl = rcu_dereference(fl->next))
+ fl = rcu_dereference_hb(fl->next))
#define for_each_fl_continue_rcu(fl) \
- for (fl = rcu_dereference(fl->next); \
+ for (fl = rcu_dereference_bh(fl->next); \
fl != NULL; \
- fl = rcu_dereference(fl->next))
+ fl = rcu_dereference_bh(fl->next))
#define for_each_sk_fl_rcu(np, sfl) \
for (sfl = rcu_dereference_bh(np->ipv6_fl_list); \
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: net: rcu warnings in ip6fl_get_first
2013-02-08 1:38 ` Cong Wang
@ 2013-02-08 3:54 ` Sasha Levin
2013-02-08 19:19 ` Paul E. McKenney
1 sibling, 0 replies; 5+ messages in thread
From: Sasha Levin @ 2013-02-08 3:54 UTC (permalink / raw)
To: Cong Wang; +Cc: linux-kernel, netdev, davem, yoshfuji
On Thu, Feb 7, 2013 at 8:38 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Thu, 07 Feb 2013 at 19:32 GMT, Sasha Levin <sasha.levin@oracle.com> wrote:
>> Hi guys,
>>
>> I got the following while fuzzing with trinity inside a KVM tools guest:
>>
>> [ 51.680236] ===============================
>> [ 51.681914] [ INFO: suspicious RCU usage. ]
>> [ 51.683610] 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276 Tainted: G W
>> [ 51.686703] -------------------------------
>> [ 51.688281] net/ipv6/ip6_flowlabel.c:671 suspicious rcu_dereference_check() usage!
>> [ 51.691345]
>
> It should use rcu_dereference_bh()...
>
> diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
> index ea42bf4..c50080f 100644
> --- a/net/ipv6/ip6_flowlabel.c
> +++ b/net/ipv6/ip6_flowlabel.c
> @@ -65,13 +65,13 @@ static DEFINE_SPINLOCK(ip6_fl_lock);
> static DEFINE_SPINLOCK(ip6_sk_fl_lock);
>
> #define for_each_fl_rcu(hash, fl) \
> - for (fl = rcu_dereference(fl_ht[(hash)]); \
> + for (fl = rcu_dereference_bh(fl_ht[(hash)]); \
> fl != NULL; \
> - fl = rcu_dereference(fl->next))
> + fl = rcu_dereference_hb(fl->next))
> #define for_each_fl_continue_rcu(fl) \
> - for (fl = rcu_dereference(fl->next); \
> + for (fl = rcu_dereference_bh(fl->next); \
> fl != NULL; \
> - fl = rcu_dereference(fl->next))
> + fl = rcu_dereference_bh(fl->next))
>
> #define for_each_sk_fl_rcu(np, sfl) \
> for (sfl = rcu_dereference_bh(np->ipv6_fl_list); \
Yup, that's how I fixed it locally and it was running without warnings
for couple of hours now.
Thanks,
Sasha
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: net: rcu warnings in ip6fl_get_first
2013-02-08 1:38 ` Cong Wang
2013-02-08 3:54 ` Sasha Levin
@ 2013-02-08 19:19 ` Paul E. McKenney
1 sibling, 0 replies; 5+ messages in thread
From: Paul E. McKenney @ 2013-02-08 19:19 UTC (permalink / raw)
To: Cong Wang; +Cc: linux-kernel, netdev
On Fri, Feb 08, 2013 at 01:38:29AM +0000, Cong Wang wrote:
> On Thu, 07 Feb 2013 at 19:32 GMT, Sasha Levin <sasha.levin@oracle.com> wrote:
> > Hi guys,
> >
> > I got the following while fuzzing with trinity inside a KVM tools guest:
> >
> > [ 51.680236] ===============================
> > [ 51.681914] [ INFO: suspicious RCU usage. ]
> > [ 51.683610] 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276 Tainted: G W
> > [ 51.686703] -------------------------------
> > [ 51.688281] net/ipv6/ip6_flowlabel.c:671 suspicious rcu_dereference_check() usage!
> > [ 51.691345]
>
> It should use rcu_dereference_bh()...
>
> diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
> index ea42bf4..c50080f 100644
> --- a/net/ipv6/ip6_flowlabel.c
> +++ b/net/ipv6/ip6_flowlabel.c
> @@ -65,13 +65,13 @@ static DEFINE_SPINLOCK(ip6_fl_lock);
> static DEFINE_SPINLOCK(ip6_sk_fl_lock);
>
> #define for_each_fl_rcu(hash, fl) \
> - for (fl = rcu_dereference(fl_ht[(hash)]); \
> + for (fl = rcu_dereference_bh(fl_ht[(hash)]); \
> fl != NULL; \
> - fl = rcu_dereference(fl->next))
> + fl = rcu_dereference_hb(fl->next))
Small but important typo in the preceding line, should be:
+ fl = rcu_dereference_bh(fl->next))
Thanx, Paul
> #define for_each_fl_continue_rcu(fl) \
> - for (fl = rcu_dereference(fl->next); \
> + for (fl = rcu_dereference_bh(fl->next); \
> fl != NULL; \
> - fl = rcu_dereference(fl->next))
> + fl = rcu_dereference_bh(fl->next))
>
> #define for_each_sk_fl_rcu(np, sfl) \
> for (sfl = rcu_dereference_bh(np->ipv6_fl_list); \
>
> --
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^ permalink raw reply [flat|nested] 5+ messages in thread
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2013-02-07 19:32 net: rcu warnings in ip6fl_get_first Sasha Levin
2013-02-08 1:37 ` Cong Wang
2013-02-08 1:38 ` Cong Wang
2013-02-08 3:54 ` Sasha Levin
2013-02-08 19:19 ` Paul E. McKenney
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