[lock validator] inet6_destroy_sock(): soft-safe -> soft-unsafe lock dependency
From: Ingo Molnar
Date: Sat Jan 28 2006 - 10:25:14 EST
* Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:
> Good catch. In fact the other spin lock operation in the same file
> needs BH protection as well since it is invoked by the output route
> path which can be in user-context for local packets.
ok, cool.
Today i've added rwlocks to the coverage of the validator too, and it
triggers in the networking code straight away - see the output below. Is
this a genuine deadlock-site too? (Take this with a large grain of salt
- while it did find another genuine bug in floppy.c and it passes a
couple of testcases too, the rwlock validation feature is literally just
1 hour old.)
let me know if you need explanation about the output, or if you need
more info.
Ingo
===========================================================
[ BUG: soft-safe -> soft-unsafe lock dependency detected! ]
-----------------------------------------------------------
sshd/2853 [HC0[0]:SC0[1]:HE1:SE0] is trying to acquire:
(&newsk->sk_dst_lock){+-}, at: [<c048f385>] inet6_destroy_sock+0x25/0x100
and this task is already holding:
(&((sk)->sk_lock.slock)){+-}, at: [<c0464832>] tcp_close+0x142/0x650
which would create a new lock dependency:
(&((sk)->sk_lock.slock)){+-} -> (&newsk->sk_dst_lock){+-}
but this new dependency connects a softirq-safe lock:
(&((sk)->sk_lock.slock)){+-}, at: [<c0464832>] tcp_close+0x142/0x650
... which became softirq-safe at:
... [<c0102e27>] sysenter_past_esp+0x84/0x8d
to a softirq-unsafe lock:
(&newsk->sk_dst_lock){+-}, at: [<c048f385>] inet6_destroy_sock+0x25/0x100
... which became softirq-unsafe at:
... [<00000000>] 0x0
which could lead to deadlocks!
other info that might help us debug this:
1 locks held by sshd/2853:
#0: (&((sk)->sk_lock.slock)){+-}, at: [<c0464832>] tcp_close+0x142/0x650
the softirq-safe lock's dependencies:
-> (&((sk)->sk_lock.slock)){+-} {
used at: [<c0438429>] lock_sock+0x29/0xd0
in-softirq at: [<c047081b>] tcp_delack_timer+0x1b/0x200
hardirq-on at: [<c0102e27>] sysenter_past_esp+0x84/0x8d
}
... key at: [<c0438375>] sock_lock_init+0x15/0x30
... acquired at: [<c0464832>] tcp_close+0x142/0x650
-> (&sk->sk_callback_lock){+-} {
used at: [<c048c8b3>] unix_release_sock+0x43/0x2d0
hardirq-on at: [<c0162738>] kmem_cache_free+0x78/0xb0
}
... key at: [<c043963f>] sock_init_data+0x10f/0x1d0
... acquired at: [<c046484e>] tcp_close+0x15e/0x650
-> (cpa_lock){++} {
used at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-hardirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-softirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
}
... key at: [<c0581950>] cpa_lock+0x10/0x40
... acquired at: [<c011474c>] change_page_attr+0x1c/0x2a0
-> (&dev->queue_lock){+-} {
used at: [<c044d44d>] qdisc_lock_tree+0x1d/0x20
in-softirq at: [<c0441ef4>] dev_queue_xmit+0x64/0x290
hardirq-on at: [<c0102ea7>] restore_nocheck+0x8/0xb
}
... key at: [<c044288b>] register_netdevice+0x4b/0x3a0
... acquired at: [<c0441ef4>] dev_queue_xmit+0x64/0x290
-> (&dev->xmit_lock){+-} {
used at: [<c0443e6c>] dev_mc_upload+0x1c/0x40
in-softirq at: [<c044d6bb>] dev_watchdog+0x1b/0xc0
hardirq-on at: [<c04d40fa>] __mutex_lock_slowpath+0x27a/0x4e0
}
... key at: [<c044289d>] register_netdevice+0x5d/0x3a0
... acquired at: [<c044e019>] dev_activate+0x69/0x110
-> (&tp->lock){++} {
used at: [<c0338c8a>] rtl8139_interrupt+0x2a/0x5e0
in-hardirq at: [<c0338c8a>] rtl8139_interrupt+0x2a/0x5e0
in-softirq at: [<c033839a>] rtl8139_start_xmit+0x7a/0x1a0
}
... key at: [<c03376bb>] rtl8139_init_one+0x2ab/0x960
... acquired at: [<c0337d92>] rtl8139_set_rx_mode+0x22/0x180
-> (&base->t_base.lock){++} {
used at: [<c01269f3>] lock_timer_base+0x23/0x50
in-hardirq at: [<c01269f3>] lock_timer_base+0x23/0x50
in-softirq at: [<c0127612>] run_timer_softirq+0x42/0x1f0
}
... key at: [<c1fdaef0>] 0xc1fdaef0
... acquired at: [<c01269f3>] lock_timer_base+0x23/0x50
-> (modlist_lock){++} {
used at: [<c0140289>] module_text_address+0x19/0x40
in-hardirq at: [<c0140289>] module_text_address+0x19/0x40
in-softirq at: [<c0140289>] module_text_address+0x19/0x40
}
... key at: [<c05842f0>] modlist_lock+0x10/0x40
... acquired at: [<c0140289>] module_text_address+0x19/0x40
-> (cpa_lock){++} {
used at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-hardirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-softirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
}
... key at: [<c0581950>] cpa_lock+0x10/0x40
... acquired at: [<c011474c>] change_page_attr+0x1c/0x2a0
-> (&tcp_hashinfo.ehash[i].lock){+-} {
used at: [<c0460dbd>] inet_hash_connect+0x3dd/0x480
in-softirq at: [<c0460eed>] __inet_twsk_hashdance+0x8d/0x130
hardirq-on at: [<c0161b26>] kmem_cache_alloc+0x96/0xd0
}
... key at: [<c0696b8d>] tcp_init+0x2ad/0x300
... acquired at: [<c0472fa4>] tcp_v4_syn_recv_sock+0x184/0x340
-> (&tcp_hashinfo.bhash[i].lock){+-} {
used at: [<c046275a>] inet_csk_get_port+0xea/0x240
in-softirq at: [<c0460eaa>] __inet_twsk_hashdance+0x4a/0x130
hardirq-on at: [<c0102e27>] sysenter_past_esp+0x84/0x8d
}
... key at: [<c0696b44>] tcp_init+0x264/0x300
... acquired at: [<c0472ffe>] tcp_v4_syn_recv_sock+0x1de/0x340
-> (&parent->list_lock){++} {
used at: [<c0161bca>] cache_alloc_refill+0x6a/0x730
in-hardirq at: [<c016362b>] do_drain+0x2b/0x60
in-softirq at: [<c0162a46>] free_block+0x136/0x150
}
... key at: [<c01610ba>] kmem_list3_init+0x3a/0x50
... acquired at: [<c0161bca>] cache_alloc_refill+0x6a/0x730
-> (&cachep->spinlock){+-} {
used at: [<c0161ea2>] cache_alloc_refill+0x342/0x730
in-softirq at: [<c0161ea2>] cache_alloc_refill+0x342/0x730
}
... key at: [<c0163c71>] kmem_cache_create+0x2c1/0x780
... acquired at: [<c0161ea2>] cache_alloc_refill+0x342/0x730
-> (&parent->list_lock){++} {
used at: [<c0161bca>] cache_alloc_refill+0x6a/0x730
in-hardirq at: [<c016362b>] do_drain+0x2b/0x60
in-softirq at: [<c0162a46>] free_block+0x136/0x150
}
... key at: [<c01610ba>] kmem_list3_init+0x3a/0x50
... acquired at: [<c01636a1>] __cache_shrink+0x41/0x140
-> (cpa_lock){++} {
used at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-hardirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-softirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
}
... key at: [<c0581950>] cpa_lock+0x10/0x40
... acquired at: [<c011474c>] change_page_attr+0x1c/0x2a0
-> (cpa_lock){++} {
used at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-hardirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-softirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
}
... key at: [<c0581950>] cpa_lock+0x10/0x40
... acquired at: [<c011474c>] change_page_attr+0x1c/0x2a0
-> (&tcp_hashinfo.ehash[i].lock){+-} {
used at: [<c0460dbd>] inet_hash_connect+0x3dd/0x480
in-softirq at: [<c0460eed>] __inet_twsk_hashdance+0x8d/0x130
hardirq-on at: [<c0161b26>] kmem_cache_alloc+0x96/0xd0
}
... key at: [<c0696b8d>] tcp_init+0x2ad/0x300
... acquired at: [<c0460dbd>] inet_hash_connect+0x3dd/0x480
-> (&queue->syn_wait_lock){+-} {
used at: [<c043a7bc>] reqsk_queue_alloc+0x8c/0xd0
in-softirq at: [<c0461e88>] inet_csk_reqsk_queue_hash_add+0xd8/0x110
hardirq-on at: [<c04d5105>] _spin_unlock_irqrestore+0x25/0x30
}
... key at: [<c043a7a2>] reqsk_queue_alloc+0x72/0xd0
... acquired at: [<c0475bf2>] tcp_check_req+0x2c2/0x3f0
-> (&base->t_base.lock){++} {
used at: [<c01269f3>] lock_timer_base+0x23/0x50
in-hardirq at: [<c01269f3>] lock_timer_base+0x23/0x50
in-softirq at: [<c0127612>] run_timer_softirq+0x42/0x1f0
}
... key at: [<c1fd2ef0>] 0xc1fd2ef0
... acquired at: [<c01269f3>] lock_timer_base+0x23/0x50
-> (modlist_lock){++} {
used at: [<c0140289>] module_text_address+0x19/0x40
in-hardirq at: [<c0140289>] module_text_address+0x19/0x40
in-softirq at: [<c0140289>] module_text_address+0x19/0x40
}
... key at: [<c05842f0>] modlist_lock+0x10/0x40
... acquired at: [<c0140289>] module_text_address+0x19/0x40
-> (&q->lock){++} {
used at: [<c0132050>] add_wait_queue+0x20/0x50
in-hardirq at: [<c0114fab>] __wake_up+0x1b/0x50
in-softirq at: [<c0114fab>] __wake_up+0x1b/0x50
}
... key at: [<c0131e62>] init_waitqueue_head+0x12/0x20
... acquired at: [<c0114fab>] __wake_up+0x1b/0x50
-> (&rq->lock){++} {
used at: [<c01162a9>] init_idle+0x49/0x70
in-hardirq at: [<c0117fb6>] scheduler_tick+0xe6/0x380
in-softirq at: [<c01175ae>] try_to_wake_up+0x3e/0x410
}
... key at: [<c1fda4f0>] 0xc1fda4f0
... acquired at: [<c01175ae>] try_to_wake_up+0x3e/0x410
-> (&rq->lock){++} {
used at: [<c01162a9>] init_idle+0x49/0x70
in-hardirq at: [<c0117fb6>] scheduler_tick+0xe6/0x380
in-softirq at: [<c0117fe7>] scheduler_tick+0x117/0x380
}
... key at: [<c1fd24f0>] 0xc1fd24f0
... acquired at: [<c01175ae>] try_to_wake_up+0x3e/0x410
-> (&rq->lock){++} {
used at: [<c01162a9>] init_idle+0x49/0x70
in-hardirq at: [<c0117fb6>] scheduler_tick+0xe6/0x380
in-softirq at: [<c01175ae>] try_to_wake_up+0x3e/0x410
}
... key at: [<c1fda4f0>] 0xc1fda4f0
... acquired at: [<c0114e6c>] double_rq_lock+0x3c/0x50
-> (&parent->list_lock){++} {
used at: [<c0161bca>] cache_alloc_refill+0x6a/0x730
in-hardirq at: [<c016362b>] do_drain+0x2b/0x60
in-softirq at: [<c0162a46>] free_block+0x136/0x150
}
... key at: [<c01610ba>] kmem_list3_init+0x3a/0x50
... acquired at: [<c0161bca>] cache_alloc_refill+0x6a/0x730
-> (&cachep->spinlock){+-} {
used at: [<c0161ea2>] cache_alloc_refill+0x342/0x730
in-softirq at: [<c0161ea2>] cache_alloc_refill+0x342/0x730
}
... key at: [<c0163c71>] kmem_cache_create+0x2c1/0x780
... acquired at: [<c0161ea2>] cache_alloc_refill+0x342/0x730
-> (&parent->list_lock){++} {
used at: [<c0161bca>] cache_alloc_refill+0x6a/0x730
in-hardirq at: [<c016362b>] do_drain+0x2b/0x60
in-softirq at: [<c0162a46>] free_block+0x136/0x150
}
... key at: [<c01610ba>] kmem_list3_init+0x3a/0x50
... acquired at: [<c01636a1>] __cache_shrink+0x41/0x140
-> (cpa_lock){++} {
used at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-hardirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
in-softirq at: [<c011474c>] change_page_attr+0x1c/0x2a0
}
... key at: [<c0581950>] cpa_lock+0x10/0x40
... acquired at: [<c011474c>] change_page_attr+0x1c/0x2a0
-> (&newsk->sk_callback_lock){+-} {
used at: [<c047f9ad>] inet_accept+0x4d/0xc0
hardirq-on at: [<c0162738>] kmem_cache_free+0x78/0xb0
}
... key at: [<c04399fb>] sk_clone+0xeb/0x1c0
... acquired at: [<c046484e>] tcp_close+0x15e/0x650
the softirq-unsafe lock's dependencies:
-> (&newsk->sk_dst_lock){+-} {
used at: [<c045fda6>] ip_setsockopt+0x526/0xbf0
softirq-on at: [<c04384c1>] lock_sock+0xc1/0xd0
hardirq-on at: [<c0102e27>] sysenter_past_esp+0x84/0x8d
}
... key at: [<c04399e9>] sk_clone+0xd9/0x1c0
... acquired at: [<c048f385>] inet6_destroy_sock+0x25/0x100
stack backtrace:
[<c010432d>] show_trace+0xd/0x10
[<c0104347>] dump_stack+0x17/0x20
[<c01380f0>] check_mask+0x2b0/0x300
[<c013a109>] debug_lock_chain+0xce9/0x1090
[<c013a4ed>] debug_lock_chain_spin+0x3d/0x60
[<c02684f2>] _raw_write_lock+0x32/0x1a0
[<c04d50d8>] _write_lock+0x8/0x10
[<c048f385>] inet6_destroy_sock+0x25/0x100
[<c04aede2>] tcp_v6_destroy_sock+0x12/0x20
[<c046217a>] inet_csk_destroy_sock+0x4a/0x150
[<c0464b7f>] tcp_close+0x48f/0x650
[<c047ffa7>] inet_release+0x37/0x60
[<c048ed10>] inet6_release+0x30/0x40
[<c0436957>] sock_release+0x17/0xa0
[<c0436df1>] sock_close+0x21/0x40
[<c01674e3>] __fput+0xb3/0x170
[<c01675c7>] fput+0x27/0x50
[<c01647d7>] filp_close+0x47/0x80
[<c011e685>] put_files_struct+0x85/0xf0
[<c011f58e>] do_exit+0x14e/0x840
[<c011fcbd>] do_group_exit+0x3d/0xa0
[<c011fd2f>] sys_exit_group+0xf/0x20
[<c0102df7>] sysenter_past_esp+0x54/0x8d
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