Re: [PATCH] RCU: don't turn off lockdep when find suspicious rcu_dereference_check() usage
From: Miles Lane
Date: Fri Apr 23 2010 - 08:51:12 EST
Hi Paul,
There has been a bit of back and forth, and I am not sure what patches
I should test now.
Could you send me a bundle of whatever needs testing now?
I currently have a build of 2.6.34-rc5-git3 with the same patch I
tested before applied.
I notice a few minor differences in the warnings given. I suspect
these do not indicate
new issues, since the trace from <IRQ> through <EOI> is the same as before.
[ 60.174809] [ INFO: suspicious rcu_dereference_check() usage. ]
[ 60.174812] ---------------------------------------------------
[ 60.174816] net/mac80211/sta_info.c:886 invoked
rcu_dereference_check() without protection!
[ 60.174820]
[ 60.174821] other info that might help us debug this:
[ 60.174822]
[ 60.174825]
[ 60.174826] rcu_scheduler_active = 1, debug_locks = 1
[ 60.174829] no locks held by wpa_supplicant/3973.
[ 60.174832]
[ 60.174833] stack backtrace:
[ 60.174838] Pid: 3973, comm: wpa_supplicant Not tainted 2.6.34-rc5-git3 #19
[ 60.174841] Call Trace:
[ 60.174844] <IRQ> [<ffffffff81067faa>] lockdep_rcu_dereference+0x9d/0xa5
[ 60.174873] [<ffffffffa014e9ae>]
ieee80211_find_sta_by_hw+0x46/0x10f [mac80211]
[ 60.174886] [<ffffffffa014ea8e>] ieee80211_find_sta+0x17/0x19 [mac80211]
[ 60.174902] [<ffffffffa01a60f2>] iwl_tx_queue_reclaim+0xdb/0x1b1 [iwlcore]
[ 60.174909] [<ffffffff81068417>] ? mark_lock+0x2d/0x235
[ 60.174920] [<ffffffffa01d5f1c>] iwl5000_rx_reply_tx+0x4a9/0x556 [iwlagn]
[ 60.174927] [<ffffffff8120a2d3>] ? is_swiotlb_buffer+0x2e/0x3b
[ 60.174936] [<ffffffffa01cebf4>] iwl_rx_handle+0x163/0x2b5 [iwlagn]
[ 60.174943] [<ffffffff810688f0>] ? trace_hardirqs_on_caller+0xfa/0x13f
[ 60.174952] [<ffffffffa01cf3ac>] iwl_irq_tasklet+0x2bb/0x3c0 [iwlagn]
[ 60.174959] [<ffffffff810411df>] tasklet_action+0xa7/0x10f
[ 60.174965] [<ffffffff810421f1>] __do_softirq+0x144/0x252
[ 60.174972] [<ffffffff81003a8c>] call_softirq+0x1c/0x34
[ 60.174977] [<ffffffff810050e4>] do_softirq+0x38/0x80
[ 60.174982] [<ffffffff81041cbe>] irq_exit+0x45/0x94
[ 60.174987] [<ffffffff81004829>] do_IRQ+0xad/0xc4
[ 60.174994] [<ffffffff813cfb13>] ret_from_intr+0x0/0xf
[ 60.174997] <EOI> [<ffffffff810e5114>] ? kmem_cache_alloc+0xa9/0x15f
[ 60.175010] [<ffffffff81342182>] ? __alloc_skb+0x3d/0x155
[ 60.175016] [<ffffffff81342182>] __alloc_skb+0x3d/0x155
[ 60.175023] [<ffffffff8133d237>] sock_alloc_send_pskb+0xc0/0x2e5
[ 60.175030] [<ffffffff8133d46c>] sock_alloc_send_skb+0x10/0x12
[ 60.175036] [<ffffffff813b1ab5>] unix_stream_sendmsg+0x117/0x2e2
[ 60.175044] [<ffffffff811bdca8>] ? avc_has_perm+0x57/0x69
[ 60.175050] [<ffffffff8133b892>] ? sock_aio_write+0x0/0xcf
[ 60.175056] [<ffffffff813392c2>] __sock_sendmsg+0x59/0x64
[ 60.175062] [<ffffffff8133b94d>] sock_aio_write+0xbb/0xcf
[ 60.175069] [<ffffffff810e98b1>] do_sync_readv_writev+0xbc/0xfb
[ 60.175077] [<ffffffff811c1726>] ? selinux_file_permission+0xa2/0xaf
[ 60.175082] [<ffffffff810e9638>] ? copy_from_user+0x2a/0x2c
[ 60.175089] [<ffffffff811baf85>] ? security_file_permission+0x11/0x13
[ 60.175095] [<ffffffff810ea64e>] do_readv_writev+0xa2/0x122
[ 60.175101] [<ffffffff810ead3b>] ? fcheck_files+0x8f/0xc9
[ 60.175107] [<ffffffff810ea70c>] vfs_writev+0x3e/0x49
[ 60.175113] [<ffffffff810ea7f2>] sys_writev+0x45/0x8e
[ 60.175119] [<ffffffff81002b6b>] system_call_fastpath+0x16/0x1b
[ 60.223213] [ INFO: suspicious rcu_dereference_check() usage. ]
[ 60.223216] ---------------------------------------------------
[ 60.223221] net/mac80211/sta_info.c:886 invoked
rcu_dereference_check() without protection!
[ 60.223224]
[ 60.223225] other info that might help us debug this:
[ 60.223227]
[ 60.223230]
[ 60.223230] rcu_scheduler_active = 1, debug_locks = 1
[ 60.223234] no locks held by udisks-daemon/4398.
[ 60.223236]
[ 60.223237] stack backtrace:
[ 60.223242] Pid: 4398, comm: udisks-daemon Not tainted 2.6.34-rc5-git3 #19
[ 60.223245] Call Trace:
[ 60.223249] <IRQ> [<ffffffff81067faa>] lockdep_rcu_dereference+0x9d/0xa5
[ 60.223275] [<ffffffffa014e9fe>]
ieee80211_find_sta_by_hw+0x96/0x10f [mac80211]
[ 60.223288] [<ffffffffa014ea8e>] ieee80211_find_sta+0x17/0x19 [mac80211]
[ 60.223304] [<ffffffffa01a60f2>] iwl_tx_queue_reclaim+0xdb/0x1b1 [iwlcore]
[ 60.223310] [<ffffffff81068417>] ? mark_lock+0x2d/0x235
[ 60.223321] [<ffffffffa01d5f1c>] iwl5000_rx_reply_tx+0x4a9/0x556 [iwlagn]
[ 60.223329] [<ffffffff8120a2d3>] ? is_swiotlb_buffer+0x2e/0x3b
[ 60.223338] [<ffffffffa01cebf4>] iwl_rx_handle+0x163/0x2b5 [iwlagn]
[ 60.223344] [<ffffffff810688f0>] ? trace_hardirqs_on_caller+0xfa/0x13f
[ 60.223353] [<ffffffffa01cf3ac>] iwl_irq_tasklet+0x2bb/0x3c0 [iwlagn]
[ 60.223360] [<ffffffff810411df>] tasklet_action+0xa7/0x10f
[ 60.223367] [<ffffffff810421f1>] __do_softirq+0x144/0x252
[ 60.223374] [<ffffffff81003a8c>] call_softirq+0x1c/0x34
[ 60.223379] [<ffffffff810050e4>] do_softirq+0x38/0x80
[ 60.223384] [<ffffffff81041cbe>] irq_exit+0x45/0x94
[ 60.223389] [<ffffffff81004829>] do_IRQ+0xad/0xc4
[ 60.223396] [<ffffffff813cfb13>] ret_from_intr+0x0/0xf
[ 60.223399] <EOI> [<ffffffff810e34f1>] ? kmem_cache_free+0xb0/0x134
[ 60.223412] [<ffffffff810f391a>] ? putname+0x2d/0x36
[ 60.223417] [<ffffffff810f391a>] putname+0x2d/0x36
[ 60.223423] [<ffffffff810f5536>] user_path_at+0x5f/0x8e
[ 60.223429] [<ffffffff81068671>] ? mark_held_locks+0x52/0x70
[ 60.223435] [<ffffffff810e34ee>] ? kmem_cache_free+0xad/0x134
[ 60.223441] [<ffffffff8106890a>] ? trace_hardirqs_on_caller+0x114/0x13f
[ 60.223447] [<ffffffff81068942>] ? trace_hardirqs_on+0xd/0xf
[ 60.223454] [<ffffffff810ed93f>] vfs_fstatat+0x32/0x5d
[ 60.223460] [<ffffffff810ed9bb>] vfs_lstat+0x19/0x1b
[ 60.223465] [<ffffffff810ed9d7>] sys_newlstat+0x1a/0x38
[ 60.223471] [<ffffffff8106890a>] ? trace_hardirqs_on_caller+0x114/0x13f
[ 60.223477] [<ffffffff813cec00>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[ 60.223485] [<ffffffff81002b6b>] system_call_fastpath+0x16/0x1b
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/