Hello,
On Tue, 27 Mar 2018, Florian Westphal wrote:
> syzbot <syzbot+a46d6abf9d56b1365a72@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> [ cc Julian and trimming cc list ]
>
> > syzkaller688027/4497 is trying to acquire lock:
> > (rtnl_mutex){+.+.}, at: [<00000000bb14d7fb>] rtnl_lock+0x17/0x20
> > net/core/rtnetlink.c:74
>
> > but task is already holding lock:
> > IPVS: stopping backup sync thread 4495 ...
> > (rtnl_mutex){+.+.}, at: [<00000000bb14d7fb>] rtnl_lock+0x17/0x20
> > net/core/rtnetlink.c:74
> >
> > other info that might help us debug this:
> > Possible unsafe locking scenario:
> >
> > CPU0
> > ----
> > lock(rtnl_mutex);
> > lock(rtnl_mutex);
> >
> > *** DEADLOCK ***
> >
> > May be due to missing lock nesting notation
>
> Looks like this is real, commit e0b26cc997d57305b4097711e12e13992580ae34
> ("ipvs: call rtnl_lock early") added rtnl_lock when starting sync thread
> but socket close invokes rtnl_lock too:
I see, thanks! I'll have to move the locks into
start_sync_thread and to split make_{send,receive}_sock
to {make,setup}_{send,receive}_sock ...
> > stack backtrace:
> > rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
> > ip_mc_drop_socket+0x88/0x230 net/ipv4/igmp.c:2643
> > inet_release+0x4e/0x1c0 net/ipv4/af_inet.c:413
> > sock_release+0x8d/0x1e0 net/socket.c:595
> > start_sync_thread+0x2213/0x2b70 net/netfilter/ipvs/ip_vs_sync.c:1924
> > do_ip_vs_set_ctl+0x1139/0x1cc0 net/netfilter/ipvs/ip_vs_ctl.c:2389
Regards
--
Julian Anastasov <ja@xxxxxx>
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