Message ID | 200910020816.41323.borntraeger@de.ibm.com |
---|---|
State | Not Applicable, archived |
Delegated to: | David Miller |
Headers | show |
On Fri, 2 Oct 2009, Christian Borntraeger wrote: > since commit 02b51df1b07b4e9ca823c89284e704cadb323cd1 (proc connector: add event > for process becoming session leader) we have the following warning: > Badness at kernel/softirq.c:143 > [...] > Krnl PSW : 0404c00180000000 00000000001481d4 (local_bh_enable+0xb0/0xe0) > [...] > Call Trace: > ([<000000013fe04100>] 0x13fe04100) > [<000000000048a946>] sk_filter+0x9a/0xd0 > [<000000000049d938>] netlink_broadcast+0x2c0/0x53c > [<00000000003ba9ae>] cn_netlink_send+0x272/0x2b0 > [<00000000003baef0>] proc_sid_connector+0xc4/0xd4 > [<0000000000142604>] __set_special_pids+0x58/0x90 > [<0000000000159938>] sys_setsid+0xb4/0xd8 > [<00000000001187fe>] sysc_noemu+0x10/0x16 > [<00000041616cb266>] 0x41616cb266 > > The warning is > ---> WARN_ON_ONCE(in_irq() || irqs_disabled()); > > The network code must not be called with disabled interrupts but > sys_setsid holds the tasklist_lock with spinlock_irq while calling > the connector. > After a discussion we agreed that we can move proc_sid_connector > from __set_special_pids to sys_setsid. > We also agreed that it is sufficient to change the check from > task_session(curr) != pid into err > 0, since if we don't change the > session, this means we were already the leader and return -EPERM. > > One last thing: > There is also daemonize(), and some people might want to get a > notification in that case. Since daemonize() is only needed if a user > space does kernel_thread this does not look important (and there seems > to be no consensus if this connector should be called in daemonize). If > we really want this, we can add proc_sid_connector to daemonize() in an > additional patch (Scott?) > > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> > CCed: Scott James Remnant <scott@ubuntu.com> > CCed: Matt Helsley <matthltc@us.ibm.com> > CCed: David S. Miller <davem@davemloft.net> > Acked-by: Oleg Nesterov <oleg@redhat.com> > Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Acked-by: David Rientjes <rientjes@google.com> I was getting the same softirq warnings and later in slub in slab_alloc() at might_sleep_if(gfpflags & __GFP_WAIT) from __alloc_skb(..., GFP_KERNEL) in this context that would infinitely spam my log. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Index: linux-2.6/kernel/exit.c =================================================================== --- linux-2.6.orig/kernel/exit.c +++ linux-2.6/kernel/exit.c @@ -359,10 +359,8 @@ void __set_special_pids(struct pid *pid) { struct task_struct *curr = current->group_leader; - if (task_session(curr) != pid) { + if (task_session(curr) != pid) change_pid(curr, PIDTYPE_SID, pid); - proc_sid_connector(curr); - } if (task_pgrp(curr) != pid) change_pid(curr, PIDTYPE_PGID, pid); Index: linux-2.6/kernel/sys.c =================================================================== --- linux-2.6.orig/kernel/sys.c +++ linux-2.6/kernel/sys.c @@ -1110,6 +1110,8 @@ SYSCALL_DEFINE0(setsid) err = session; out: write_unlock_irq(&tasklist_lock); + if (err > 0) + proc_sid_connector(group_leader); return err; }