Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752192AbdCNOru (ORCPT ); Tue, 14 Mar 2017 10:47:50 -0400 Received: from mail-ua0-f174.google.com ([209.85.217.174]:35901 "EHLO mail-ua0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751111AbdCNOqa (ORCPT ); Tue, 14 Mar 2017 10:46:30 -0400 MIME-Version: 1.0 In-Reply-To: <1489502504.28631.115.camel@edumazet-glaptop3.roam.corp.google.com> References: <1489502504.28631.115.camel@edumazet-glaptop3.roam.corp.google.com> From: Dmitry Vyukov Date: Tue, 14 Mar 2017 15:46:07 +0100 Message-ID: Subject: Re: net: deadlock between ip_expire/sch_direct_xmit To: Eric Dumazet Cc: David Miller , Eric Dumazet , Cong Wang , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev , LKML , jhs@mojatatu.com, syzkaller Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 16506 Lines: 343 On Tue, Mar 14, 2017 at 3:41 PM, Eric Dumazet wrote: > On Tue, 2017-03-14 at 14:31 +0100, Dmitry Vyukov wrote: >> Hello, >> >> I've got the following deadlock report while running syzkaller fuzzer >> on net-next/92cd12c5ed432c5eebd2462d666772a8d8442c3b: >> >> >> [ INFO: possible circular locking dependency detected ] >> 4.10.0+ #29 Not tainted >> ------------------------------------------------------- >> modprobe/12392 is trying to acquire lock: >> (_xmit_ETHER#2){+.-...}, at: [] spin_lock >> include/linux/spinlock.h:299 [inline] >> (_xmit_ETHER#2){+.-...}, at: [] __netif_tx_lock >> include/linux/netdevice.h:3486 [inline] >> (_xmit_ETHER#2){+.-...}, at: [] >> sch_direct_xmit+0x282/0x6d0 net/sched/sch_generic.c:180 >> >> but task is already holding lock: >> (&(&q->lock)->rlock){+.-...}, at: [] spin_lock >> include/linux/spinlock.h:299 [inline] >> (&(&q->lock)->rlock){+.-...}, at: [] >> ip_expire+0x51/0x6c0 net/ipv4/ip_fragment.c:201 >> >> which lock already depends on the new lock. >> >> >> the existing dependency chain (in reverse order) is: >> >> -> #1 (&(&q->lock)->rlock){+.-...}: >> validate_chain kernel/locking/lockdep.c:2267 [inline] >> __lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340 >> lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755 >> __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] >> _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151 >> spin_lock include/linux/spinlock.h:299 [inline] >> ip_defrag+0x3a2/0x4130 net/ipv4/ip_fragment.c:669 >> ip_check_defrag+0x4e3/0x8b0 net/ipv4/ip_fragment.c:713 >> packet_rcv_fanout+0x282/0x800 net/packet/af_packet.c:1459 >> deliver_skb net/core/dev.c:1834 [inline] >> dev_queue_xmit_nit+0x294/0xa90 net/core/dev.c:1890 >> xmit_one net/core/dev.c:2903 [inline] >> dev_hard_start_xmit+0x16b/0xab0 net/core/dev.c:2923 >> sch_direct_xmit+0x31f/0x6d0 net/sched/sch_generic.c:182 >> __dev_xmit_skb net/core/dev.c:3092 [inline] >> __dev_queue_xmit+0x13e5/0x1e60 net/core/dev.c:3358 >> dev_queue_xmit+0x17/0x20 net/core/dev.c:3423 >> neigh_resolve_output+0x6b9/0xb10 net/core/neighbour.c:1308 >> neigh_output include/net/neighbour.h:478 [inline] >> ip_finish_output2+0x8b8/0x15a0 net/ipv4/ip_output.c:228 >> ip_do_fragment+0x1d93/0x2720 net/ipv4/ip_output.c:672 >> ip_fragment.constprop.54+0x145/0x200 net/ipv4/ip_output.c:545 >> ip_finish_output+0x82d/0xe10 net/ipv4/ip_output.c:314 >> NF_HOOK_COND include/linux/netfilter.h:246 [inline] >> ip_output+0x1f0/0x7a0 net/ipv4/ip_output.c:404 >> dst_output include/net/dst.h:486 [inline] >> ip_local_out+0x95/0x170 net/ipv4/ip_output.c:124 >> ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1492 >> ip_push_pending_frames+0x64/0x80 net/ipv4/ip_output.c:1512 >> raw_sendmsg+0x26de/0x3a00 net/ipv4/raw.c:655 >> inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:761 >> sock_sendmsg_nosec net/socket.c:633 [inline] >> sock_sendmsg+0xca/0x110 net/socket.c:643 >> ___sys_sendmsg+0x4a3/0x9f0 net/socket.c:1985 >> __sys_sendmmsg+0x25c/0x750 net/socket.c:2075 >> SYSC_sendmmsg net/socket.c:2106 [inline] >> SyS_sendmmsg+0x35/0x60 net/socket.c:2101 >> do_syscall_64+0x2e8/0x930 arch/x86/entry/common.c:281 >> return_from_SYSCALL_64+0x0/0x7a >> >> -> #0 (_xmit_ETHER#2){+.-...}: >> check_prev_add kernel/locking/lockdep.c:1830 [inline] >> check_prevs_add+0xa8f/0x19f0 kernel/locking/lockdep.c:1940 >> validate_chain kernel/locking/lockdep.c:2267 [inline] >> __lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340 >> lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755 >> __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] >> _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151 >> spin_lock include/linux/spinlock.h:299 [inline] >> __netif_tx_lock include/linux/netdevice.h:3486 [inline] >> sch_direct_xmit+0x282/0x6d0 net/sched/sch_generic.c:180 >> __dev_xmit_skb net/core/dev.c:3092 [inline] >> __dev_queue_xmit+0x13e5/0x1e60 net/core/dev.c:3358 >> dev_queue_xmit+0x17/0x20 net/core/dev.c:3423 >> neigh_hh_output include/net/neighbour.h:468 [inline] >> neigh_output include/net/neighbour.h:476 [inline] >> ip_finish_output2+0xf6c/0x15a0 net/ipv4/ip_output.c:228 >> ip_finish_output+0xa29/0xe10 net/ipv4/ip_output.c:316 >> NF_HOOK_COND include/linux/netfilter.h:246 [inline] >> ip_output+0x1f0/0x7a0 net/ipv4/ip_output.c:404 >> dst_output include/net/dst.h:486 [inline] >> ip_local_out+0x95/0x170 net/ipv4/ip_output.c:124 >> ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1492 >> ip_push_pending_frames+0x64/0x80 net/ipv4/ip_output.c:1512 >> icmp_push_reply+0x372/0x4d0 net/ipv4/icmp.c:394 >> icmp_send+0x156c/0x1c80 net/ipv4/icmp.c:754 >> ip_expire+0x40e/0x6c0 net/ipv4/ip_fragment.c:239 >> call_timer_fn+0x241/0x820 kernel/time/timer.c:1268 >> expire_timers kernel/time/timer.c:1307 [inline] >> __run_timers+0x960/0xcf0 kernel/time/timer.c:1601 >> run_timer_softirq+0x21/0x80 kernel/time/timer.c:1614 >> __do_softirq+0x31f/0xbe7 kernel/softirq.c:284 >> invoke_softirq kernel/softirq.c:364 [inline] >> irq_exit+0x1cc/0x200 kernel/softirq.c:405 >> exiting_irq arch/x86/include/asm/apic.h:657 [inline] >> smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:962 >> apic_timer_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:707 >> __read_once_size include/linux/compiler.h:254 [inline] >> atomic_read arch/x86/include/asm/atomic.h:26 [inline] >> rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:350 [inline] >> __rcu_is_watching kernel/rcu/tree.c:1133 [inline] >> rcu_is_watching+0x83/0x110 kernel/rcu/tree.c:1147 >> rcu_read_lock_held+0x87/0xc0 kernel/rcu/update.c:293 >> radix_tree_deref_slot include/linux/radix-tree.h:238 [inline] >> filemap_map_pages+0x6d4/0x1570 mm/filemap.c:2335 >> do_fault_around mm/memory.c:3231 [inline] >> do_read_fault mm/memory.c:3265 [inline] >> do_fault+0xbd5/0x2080 mm/memory.c:3370 >> handle_pte_fault mm/memory.c:3600 [inline] >> __handle_mm_fault+0x1062/0x2cb0 mm/memory.c:3714 >> handle_mm_fault+0x1e2/0x480 mm/memory.c:3751 >> __do_page_fault+0x4f6/0xb60 arch/x86/mm/fault.c:1397 >> do_page_fault+0x54/0x70 arch/x86/mm/fault.c:1460 >> page_fault+0x28/0x30 arch/x86/entry/entry_64.S:1011 >> >> other info that might help us debug this: >> >> Possible unsafe locking scenario: >> >> CPU0 CPU1 >> ---- ---- >> lock(&(&q->lock)->rlock); >> lock(_xmit_ETHER#2); >> lock(&(&q->lock)->rlock); >> lock(_xmit_ETHER#2); >> >> *** DEADLOCK *** >> >> 10 locks held by modprobe/12392: >> #0: (&mm->mmap_sem){++++++}, at: [] >> __do_page_fault+0x2b8/0xb60 arch/x86/mm/fault.c:1336 >> #1: (rcu_read_lock){......}, at: [] >> filemap_map_pages+0x1e6/0x1570 mm/filemap.c:2324 >> #2: (&(ptlock_ptr(page))->rlock#2){+.+...}, at: [] >> spin_lock include/linux/spinlock.h:299 [inline] >> #2: (&(ptlock_ptr(page))->rlock#2){+.+...}, at: [] >> pte_alloc_one_map mm/memory.c:2944 [inline] >> #2: (&(ptlock_ptr(page))->rlock#2){+.+...}, at: [] >> alloc_set_pte+0x13b8/0x1b90 mm/memory.c:3072 >> #3: (((&q->timer))){+.-...}, at: [] >> lockdep_copy_map include/linux/lockdep.h:175 [inline] >> #3: (((&q->timer))){+.-...}, at: [] >> call_timer_fn+0x1c2/0x820 kernel/time/timer.c:1258 >> #4: (&(&q->lock)->rlock){+.-...}, at: [] spin_lock >> include/linux/spinlock.h:299 [inline] >> #4: (&(&q->lock)->rlock){+.-...}, at: [] >> ip_expire+0x51/0x6c0 net/ipv4/ip_fragment.c:201 >> #5: (rcu_read_lock){......}, at: [] >> ip_expire+0x1b3/0x6c0 net/ipv4/ip_fragment.c:216 >> #6: (slock-AF_INET){+.-...}, at: [] spin_trylock >> include/linux/spinlock.h:309 [inline] >> #6: (slock-AF_INET){+.-...}, at: [] icmp_xmit_lock >> net/ipv4/icmp.c:219 [inline] >> #6: (slock-AF_INET){+.-...}, at: [] >> icmp_send+0x803/0x1c80 net/ipv4/icmp.c:681 >> #7: (rcu_read_lock_bh){......}, at: [] >> ip_finish_output2+0x2c1/0x15a0 net/ipv4/ip_output.c:198 >> #8: (rcu_read_lock_bh){......}, at: [] >> __dev_queue_xmit+0x23e/0x1e60 net/core/dev.c:3324 >> #9: (dev->qdisc_running_key ?: &qdisc_running_key){+.....}, at: >> [] dev_queue_xmit+0x17/0x20 net/core/dev.c:3423 >> >> stack backtrace: >> CPU: 0 PID: 12392 Comm: modprobe Not tainted 4.10.0+ #29 >> Hardware name: Google Google Compute Engine/Google Compute Engine, >> BIOS Google 01/01/2011 >> Call Trace: >> >> __dump_stack lib/dump_stack.c:16 [inline] >> dump_stack+0x2ee/0x3ef lib/dump_stack.c:52 >> print_circular_bug+0x307/0x3b0 kernel/locking/lockdep.c:1204 >> check_prev_add kernel/locking/lockdep.c:1830 [inline] >> check_prevs_add+0xa8f/0x19f0 kernel/locking/lockdep.c:1940 >> validate_chain kernel/locking/lockdep.c:2267 [inline] >> __lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340 >> lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755 >> __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] >> _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151 >> spin_lock include/linux/spinlock.h:299 [inline] >> __netif_tx_lock include/linux/netdevice.h:3486 [inline] >> sch_direct_xmit+0x282/0x6d0 net/sched/sch_generic.c:180 >> __dev_xmit_skb net/core/dev.c:3092 [inline] >> __dev_queue_xmit+0x13e5/0x1e60 net/core/dev.c:3358 >> dev_queue_xmit+0x17/0x20 net/core/dev.c:3423 >> neigh_hh_output include/net/neighbour.h:468 [inline] >> neigh_output include/net/neighbour.h:476 [inline] >> ip_finish_output2+0xf6c/0x15a0 net/ipv4/ip_output.c:228 >> ip_finish_output+0xa29/0xe10 net/ipv4/ip_output.c:316 >> NF_HOOK_COND include/linux/netfilter.h:246 [inline] >> ip_output+0x1f0/0x7a0 net/ipv4/ip_output.c:404 >> dst_output include/net/dst.h:486 [inline] >> ip_local_out+0x95/0x170 net/ipv4/ip_output.c:124 >> ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1492 >> ip_push_pending_frames+0x64/0x80 net/ipv4/ip_output.c:1512 >> icmp_push_reply+0x372/0x4d0 net/ipv4/icmp.c:394 >> icmp_send+0x156c/0x1c80 net/ipv4/icmp.c:754 >> ip_expire+0x40e/0x6c0 net/ipv4/ip_fragment.c:239 >> call_timer_fn+0x241/0x820 kernel/time/timer.c:1268 >> expire_timers kernel/time/timer.c:1307 [inline] >> __run_timers+0x960/0xcf0 kernel/time/timer.c:1601 >> run_timer_softirq+0x21/0x80 kernel/time/timer.c:1614 >> __do_softirq+0x31f/0xbe7 kernel/softirq.c:284 >> invoke_softirq kernel/softirq.c:364 [inline] >> irq_exit+0x1cc/0x200 kernel/softirq.c:405 >> exiting_irq arch/x86/include/asm/apic.h:657 [inline] >> smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:962 >> apic_timer_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:707 >> RIP: 0010:__read_once_size include/linux/compiler.h:254 [inline] >> RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:26 [inline] >> RIP: 0010:rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:350 [inline] >> RIP: 0010:__rcu_is_watching kernel/rcu/tree.c:1133 [inline] >> RIP: 0010:rcu_is_watching+0x83/0x110 kernel/rcu/tree.c:1147 >> RSP: 0000:ffff8801c391f120 EFLAGS: 00000a03 ORIG_RAX: ffffffffffffff10 >> RAX: dffffc0000000000 RBX: ffff8801c391f148 RCX: 0000000000000000 >> RDX: 0000000000000000 RSI: 000055edd4374000 RDI: ffff8801dbe1ae0c >> RBP: ffff8801c391f1a0 R08: 0000000000000002 R09: 0000000000000000 >> R10: dffffc0000000000 R11: 0000000000000002 R12: 1ffff10038723e25 >> R13: ffff8801dbe1ae00 R14: ffff8801c391f680 R15: dffffc0000000000 >> >> rcu_read_lock_held+0x87/0xc0 kernel/rcu/update.c:293 >> radix_tree_deref_slot include/linux/radix-tree.h:238 [inline] >> filemap_map_pages+0x6d4/0x1570 mm/filemap.c:2335 >> do_fault_around mm/memory.c:3231 [inline] >> do_read_fault mm/memory.c:3265 [inline] >> do_fault+0xbd5/0x2080 mm/memory.c:3370 >> handle_pte_fault mm/memory.c:3600 [inline] >> __handle_mm_fault+0x1062/0x2cb0 mm/memory.c:3714 >> handle_mm_fault+0x1e2/0x480 mm/memory.c:3751 >> __do_page_fault+0x4f6/0xb60 arch/x86/mm/fault.c:1397 >> do_page_fault+0x54/0x70 arch/x86/mm/fault.c:1460 >> page_fault+0x28/0x30 arch/x86/entry/entry_64.S:1011 >> RIP: 0033:0x7f83172f2786 >> RSP: 002b:00007fffe859ae80 EFLAGS: 00010293 >> RAX: 000055edd4373040 RBX: 00007f83175111c8 RCX: 000055edd4373238 >> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f8317510970 >> RBP: 00007fffe859afd0 R08: 0000000000000009 R09: 0000000000000000 >> R10: 0000000000000064 R11: 0000000000000000 R12: 000055edd4373040 >> R13: 0000000000000000 R14: 00007fffe859afe8 R15: 0000000000000000 > > > This looks a false positive. > An ICMP message can not be possibly fragmented. I am confused. Lockdep has observed both of these stacks: CPU0 CPU1 ---- ---- lock(&(&q->lock)->rlock); lock(_xmit_ETHER#2); lock(&(&q->lock)->rlock); lock(_xmit_ETHER#2); So it somehow happened. Or what do you mean? > Following patch should fix the lockdep issue. > > diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c > index bbe7f72db9c157ba2d6c5292637c2f58ad39a123..b3cdeec85f1f2c612c362590e828f50596a5c247 100644 > --- a/net/ipv4/ip_fragment.c > +++ b/net/ipv4/ip_fragment.c > @@ -198,6 +198,7 @@ static void ip_expire(unsigned long arg) > qp = container_of((struct inet_frag_queue *) arg, struct ipq, q); > net = container_of(qp->q.net, struct net, ipv4.frags); > > + rcu_read_lock(); > spin_lock(&qp->q.lock); > > if (qp->q.flags & INET_FRAG_COMPLETE) > @@ -207,7 +208,7 @@ static void ip_expire(unsigned long arg) > __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); > > if (!inet_frag_evicting(&qp->q)) { > - struct sk_buff *head = qp->q.fragments; > + struct sk_buff *clone, *head = qp->q.fragments; > const struct iphdr *iph; > int err; > > @@ -216,32 +217,40 @@ static void ip_expire(unsigned long arg) > if (!(qp->q.flags & INET_FRAG_FIRST_IN) || !qp->q.fragments) > goto out; > > - rcu_read_lock(); > head->dev = dev_get_by_index_rcu(net, qp->iif); > if (!head->dev) > - goto out_rcu_unlock; > + goto out; > + > > /* skb has no dst, perform route lookup again */ > iph = ip_hdr(head); > err = ip_route_input_noref(head, iph->daddr, iph->saddr, > iph->tos, head->dev); > if (err) > - goto out_rcu_unlock; > + goto out; > > /* Only an end host needs to send an ICMP > * "Fragment Reassembly Timeout" message, per RFC792. > */ > if (frag_expire_skip_icmp(qp->user) && > (skb_rtable(head)->rt_type != RTN_LOCAL)) > - goto out_rcu_unlock; > + goto out; > + > + clone = skb_clone(head, GFP_ATOMIC); > > /* Send an ICMP "Fragment Reassembly Timeout" message. */ > - icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); > -out_rcu_unlock: > - rcu_read_unlock(); > + if (clone) { > + spin_unlock(&qp->q.lock); > + icmp_send(clone, ICMP_TIME_EXCEEDED, > + ICMP_EXC_FRAGTIME, 0); > + consume_skb(clone); > + goto out_rcu_unlock; > + } > } > out: > spin_unlock(&qp->q.lock); > +out_rcu_unlock: > + rcu_read_unlock(); > ipq_put(qp); > } > > > >