В Пн, 01/06/2015 в 17:25 +0300, Vasily Averin пишет: > > On 01.06.2015 15:46, Kirill Tkhai wrote: > > В Пн, 01/06/2015 в 15:16 +0300, Vasily Averin пишет: > >> On 01.06.2015 14:31, Kirill Tkhai wrote: > >>> В Пт, 29/05/2015 в 17:20 +0300, Andrew Vagin пишет: > >>>> Acked-by: Andrew Vagin <[email protected]> > >>>> > >>>> I'm agree that we need to remove this function, but I don't know how it > >>>> fixes the bug. > >>> > >>> tcp_v4_kill_ve_sockets() is called when all processes are killed, > >>> and their sockets have been already replaced with time wait sockets. > >>> > >>> So, when we are iterating through chain list: > >>> > >>> sk_nulls_for_each(sk, node, &head[i].chain) > >>> > >>> we can't find TCP sockets there. Every sk is of type inet_timewait_sock. > >>> Yes, they both are linked in the same table. > >>> > >>> struct sock (tcp_sock) and inet_timewait_sock are not a child and a > >>> parent: > >>> > >>> struct sock { struct inet_timewait_sock { > >>> struct sock_common __sk_common; struct sock_common __tw_common; > >>> socket_lock_t sk_lock; int tw_timeout; > >>> > >>> They are different. > >>> > >>> So, when we are doing bh_lock_sock(sk) in tcp_v4_kill_ve_sockets(), i.e. > >>> > >>> #define bh_lock_sock(__sk) spin_lock(&((__sk)->sk_lock.slock)) > >>> > >>> we are trying to manipulate with tw_timeout, which is not zero, and can't > >>> acquire the spinlock. > >> > >> it's nice theory, but I still do not understand how is it related to > >> observed crash? > >> > >> I did not found such process in crash dump of PSBM-33755. > >> Kernel was crashed in another function, not on access to spinlock. > >> and it was happen in 50 seconds after stop of CT 106. > >> How can you explain it? > > > > You dereference time wait socket in tcp_v4_kill_ve_sockets() and use it > > as tcp socket. Starting from bh_lock_sock() and further in > > tcp_kill_ve_onesk() > > you're modifying a memory of tw socket like it'd be a tcp_sk, and this > > leads to memory corruption. > > > > Another one problem is you can't install a time wait socket for a time wait > > socket. When you do that, you're replacing old tw sock with a new in > > hashtable, > > but it still remains to be linked in death row using tw_death_node. > > Why you think that tcp_v4_kill_ve_sockets() found time wait socket? > > As far as I understand time wait sockets should be included into > inet_ehash_bucket.twchain > but tcp_v4_kill_ve_sockets processes inet_ehash_bucket.chain.
You're sure, but I spoked about 3.10. There is no twchain, everything is linked to chain. Look at __inet_twsk_hashdance() in 3.10: We unhash TCP sock from chain and hash time wait socket to there. tcp_v4_kill_ve_sockets() takes these time wait sockets and installs new time wait sockets for them. So we have a deadlock, which I described above. It was observed today in PSBM-33926. Look there for the details. If we speak about 2.6.32, we need explanation why the chain is not empty. It's not clear right now, but I think some reason will be found soon. > Could you please explain how time wait sockets was added to > inet_ehash_bucket.chain? > > >>>> On Fri, May 29, 2015 at 04:53:39PM +0300, Kirill Tkhai wrote: > >>>>> This is a leftover from earlier versions of PCS, > >>>>> and we do not need that functionality in 3.10. > >>>>> > >>>>> It was the reason of the kernel panic in 2.6.32: > >>>>> https://jira.sw.ru/browse/PSBM-33755, in the test > >>>>> of forced CT destroying. > >>>>> > >>>>> Also, tcp_v4_kill_ve_sockets() looks as the only > >>>>> user of synchronize_net(), so we're not need this > >>>>> function too (the only net hook fini_venet_acct_ip6_stat() > >>>>> from the chain doesn't need it). Besides this, there > >>>>> will be one more synchronize_rcu() later in > >>>>> ve_drop_context(). > >>>>> > >>>>> Signed-off-by: Kirill Tkhai <[email protected]> > >>>>> --- > >>>>> include/linux/ve_proto.h | 5 +-- > >>>>> kernel/ve/ve.c | 5 +-- > >>>>> net/ipv4/tcp_ipv4.c | 88 > >>>>> ---------------------------------------------- > >>>>> 3 files changed, 2 insertions(+), 96 deletions(-) > >>>>> > >>>>> diff --git a/include/linux/ve_proto.h b/include/linux/ve_proto.h > >>>>> index d491ab0..e77d6f9 100644 > >>>>> --- a/include/linux/ve_proto.h > >>>>> +++ b/include/linux/ve_proto.h > >>>>> @@ -50,12 +50,9 @@ typedef void (*ve_seq_print_t)(struct seq_file *, > >>>>> struct ve_struct *); > >>>>> void vzmon_register_veaddr_print_cb(ve_seq_print_t); > >>>>> void vzmon_unregister_veaddr_print_cb(ve_seq_print_t); > >>>>> > >>>>> -#ifdef CONFIG_INET > >>>>> -void tcp_v4_kill_ve_sockets(struct ve_struct *envid); > >>>>> -#ifdef CONFIG_VE_NETDEV > >>>>> +#if defined(CONFIG_INET) && defined(CONFIG_VE_NETDEV) > >>>>> int venet_init(void); > >>>>> #endif > >>>>> -#endif > >>>>> > >>>>> extern struct list_head ve_list_head; > >>>>> #define for_each_ve(ve) list_for_each_entry((ve), > >>>>> &ve_list_head, ve_list) > >>>>> diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c > >>>>> index 55b7d86..3128fdb 100644 > >>>>> --- a/kernel/ve/ve.c > >>>>> +++ b/kernel/ve/ve.c > >>>>> @@ -647,10 +647,7 @@ void ve_exit_ns(struct pid_namespace *pid_ns) > >>>>> > >>>>> down_write(&ve->op_sem); > >>>>> ve_hook_iterate_fini(VE_SS_CHAIN, ve); > >>>>> -#ifdef CONFIG_INET > >>>>> - tcp_v4_kill_ve_sockets(ve); > >>>>> - synchronize_net(); > >>>>> -#endif > >>>>> + > >>>>> ve_list_del(ve); > >>>>> ve_drop_context(ve); > >>>>> up_write(&ve->op_sem); > >>>>> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c > >>>>> index ad4520c..a8ef57a 100644 > >>>>> --- a/net/ipv4/tcp_ipv4.c > >>>>> +++ b/net/ipv4/tcp_ipv4.c > >>>>> @@ -2812,91 +2812,3 @@ void __init tcp_v4_init(void) > >>>>> if (register_pernet_subsys(&tcp_sk_ops)) > >>>>> panic("Failed to create the TCP control socket.\n"); > >>>>> } > >>>>> - > >>>>> -#ifdef CONFIG_VE > >>>>> -static void tcp_kill_ve_onesk(struct sock *sk) > >>>>> -{ > >>>>> - struct tcp_sock *tp = tcp_sk(sk); > >>>>> - > >>>>> - /* Check the assumed state of the socket. */ > >>>>> - if (!sock_flag(sk, SOCK_DEAD)) { > >>>>> - printk(KERN_WARNING "Killing sk: dead %d, state %d, " > >>>>> - "wrseq %u unseq %u, wrqu %d.\n", > >>>>> - sock_flag(sk, SOCK_DEAD), sk->sk_state, > >>>>> - tp->write_seq, tp->snd_una, > >>>>> - !skb_queue_empty(&sk->sk_write_queue)); > >>>>> - sk->sk_err = ECONNRESET; > >>>>> - sk->sk_error_report(sk); > >>>>> - } > >>>>> - > >>>>> - tcp_send_active_reset(sk, GFP_ATOMIC); > >>>>> - switch (sk->sk_state) { > >>>>> - case TCP_FIN_WAIT1: > >>>>> - case TCP_CLOSING: > >>>>> - /* In these 2 states the peer may want us to > >>>>> retransmit > >>>>> - * some data and/or FIN. Entering "resetting > >>>>> mode" > >>>>> - * instead. > >>>>> - */ > >>>>> - tcp_time_wait(sk, TCP_CLOSE, 0); > >>>>> - break; > >>>>> - case TCP_FIN_WAIT2: > >>>>> - /* By some reason the socket may stay in this > >>>>> state > >>>>> - * without turning into a TW bucket. Fix it. > >>>>> - */ > >>>>> - tcp_time_wait(sk, TCP_FIN_WAIT2, 0); > >>>>> - break; > >>>>> - default: > >>>>> - /* Just jump into CLOSED state. */ > >>>>> - tcp_done(sk); > >>>>> - break; > >>>>> - } > >>>>> -} > >>>>> - > >>>>> -void tcp_v4_kill_ve_sockets(struct ve_struct *envid) > >>>>> -{ > >>>>> - struct inet_ehash_bucket *head; > >>>>> - int i, retry; > >>>>> - > >>>>> - /* alive */ > >>>>> -again: > >>>>> - retry = 0; > >>>>> - local_bh_disable(); > >>>>> - head = tcp_hashinfo.ehash; > >>>>> - for (i = 0; i < tcp_hashinfo.ehash_mask; i++) { > >>>>> - struct sock *sk; > >>>>> - struct hlist_nulls_node *node; > >>>>> - spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, i); > >>>>> -more_work: > >>>>> - spin_lock(lock); > >>>>> - sk_nulls_for_each(sk, node, &head[i].chain) { > >>>>> - if (sock_net(sk)->owner_ve == envid) { > >>>>> - sock_hold(sk); > >>>>> - spin_unlock(lock); > >>>>> - > >>>>> - bh_lock_sock(sk); > >>>>> - if (sock_owned_by_user(sk)) { > >>>>> - retry = 1; > >>>>> - bh_unlock_sock(sk); > >>>>> - sock_put(sk); > >>>>> - goto enable_bh; > >>>>> - } > >>>>> - /* sk might have disappeared from the > >>>>> hash before > >>>>> - * we got the lock */ > >>>>> - if (sk->sk_state != TCP_CLOSE) > >>>>> - tcp_kill_ve_onesk(sk); > >>>>> - bh_unlock_sock(sk); > >>>>> - sock_put(sk); > >>>>> - goto more_work; > >>>>> - } > >>>>> - } > >>>>> - spin_unlock(lock); > >>>>> - } > >>>>> -enable_bh: > >>>>> - local_bh_enable(); > >>>>> - if (retry) { > >>>>> - schedule_timeout_interruptible(HZ); > >>>>> - goto again; > >>>>> - } > >>>>> -} > >>>>> -EXPORT_SYMBOL(tcp_v4_kill_ve_sockets); > >>>>> -#endif > >>>>> > >>> > >>> > >>> _______________________________________________ > >>> Devel mailing list > >>> [email protected] > >>> https://lists.openvz.org/mailman/listinfo/devel > >>> > >>> > > > > > > _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
