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SubjectRe: net: rcu warnings in ip6fl_get_first
Date
["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



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