Hello, syzbot found the following issue on: HEAD commit: 14e8e0f6 tcp: shrink inet_connection_sock icsk_mtup enable.. git tree: net-next console output: https://syzkaller.appspot.com/x/log.txt?x=114362c4d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=ac6e76902c1abb76 dashboard link: https://syzkaller.appspot.com/bug?extid=a2ec7a7fb2331091aecf compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=114d33d8d00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12610ac4d00000 The issue was bisected to: commit 0fedc63fadf0404a729e73a35349481c8009c02f Author: Cong Wang <xiyou.wangcong@xxxxxxxxx> Date: Wed Sep 23 03:56:24 2020 +0000 net_sched: commit action insertions together bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1065c1d8d00000 final oops: https://syzkaller.appspot.com/x/report.txt?x=1265c1d8d00000 console output: https://syzkaller.appspot.com/x/log.txt?x=1465c1d8d00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+a2ec7a7fb2331091aecf@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 0fedc63fadf0 ("net_sched: commit action insertions together") INFO: task kworker/u4:0:8 blocked for more than 143 seconds. Not tainted 5.11.0-rc5-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:0 state:D stack:23440 pid: 8 ppid: 2 flags:0x00004000 Workqueue: tc_filter_workqueue rsvp_delete_filter_work Call Trace: context_switch kernel/sched/core.c:4327 [inline] __schedule+0x90c/0x21a0 kernel/sched/core.c:5078 schedule+0xcf/0x270 kernel/sched/core.c:5157 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:5216 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x81a/0x1110 kernel/locking/mutex.c:1103 rsvp_delete_filter_work+0xe/0x20 net/sched/cls_rsvp.h:293 process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 INFO: task kworker/0:3:3217 blocked for more than 143 seconds. Not tainted 5.11.0-rc5-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:3 state:D stack:26720 pid: 3217 ppid: 2 flags:0x00004000 Workqueue: ipv6_addrconf addrconf_verify_work Call Trace: context_switch kernel/sched/core.c:4327 [inline] __schedule+0x90c/0x21a0 kernel/sched/core.c:5078 schedule+0xcf/0x270 kernel/sched/core.c:5157 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:5216 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x81a/0x1110 kernel/locking/mutex.c:1103 addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4572 process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Showing all locks held in the system: 3 locks held by kworker/u4:0/8: #0: ffff88814156a938 ((wq_completion)tc_filter_workqueue){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff88814156a938 ((wq_completion)tc_filter_workqueue){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff88814156a938 ((wq_completion)tc_filter_workqueue){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff88814156a938 ((wq_completion)tc_filter_workqueue){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff88814156a938 ((wq_completion)tc_filter_workqueue){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff88814156a938 ((wq_completion)tc_filter_workqueue){+.+.}-{0:0}, at: process_one_work+0x871/0x15f0 kernel/workqueue.c:2246 #1: ffffc90000cd7da8 ((work_completion)(&(rwork)->work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x15f0 kernel/workqueue.c:2250 #2: ffffffff8ca5a488 (rtnl_mutex){+.+.}-{3:3}, at: rsvp_delete_filter_work+0xe/0x20 net/sched/cls_rsvp.h:293 1 lock held by khungtaskd/1659: #0: ffffffff8b373d20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6259 3 locks held by kworker/0:3/3217: #0: ffff8881472c5138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8881472c5138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff8881472c5138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff8881472c5138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff8881472c5138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff8881472c5138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x871/0x15f0 kernel/workqueue.c:2246 #1: ffffc90001e1fda8 ((addr_chk_work).work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x15f0 kernel/workqueue.c:2250 #2: ffffffff8ca5a488 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4572 1 lock held by in:imklog/8196: #0: ffff888012330370 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:947 1 lock held by syz-executor200/8491: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1659 Comm: khungtaskd Not tainted 5.11.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] watchdog+0xd43/0xfa0 kernel/hung_task.c:294 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 8491 Comm: syz-executor200 Not tainted 5.11.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:match_held_lock+0x0/0x150 kernel/locking/lockdep.c:4891 Code: cc cc cc cc cc cc cc cc cc cc 0f 1f 44 00 00 48 8b 34 24 48 c7 c7 c0 25 4a 89 e8 b8 2a bf ff cc cc cc cc cc cc cc cc cc cc cc <48> 39 77 10 0f 84 97 00 00 00 66 f7 47 22 f0 ff 74 4b 48 83 ec 08 RSP: 0018:ffffc9000197ecd8 EFLAGS: 00000002 RAX: 0000000000000005 RBX: 0000000000000002 RCX: ffffc9000197ed68 RDX: 0000000000000002 RSI: ffff8880212a6c68 RDI: ffff888022122570 RBP: 1ffff9200032fda5 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff888022122570 R13: ffff8880212a6c68 R14: ffffc9000197ed68 R15: 0000000000000001 FS: 0000000001643880(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000080 CR3: 0000000020ad5000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: find_held_lock+0x2d/0x110 kernel/locking/lockdep.c:4935 __lock_release kernel/locking/lockdep.c:5119 [inline] lock_release+0x1f2/0x710 kernel/locking/lockdep.c:5462 __mutex_unlock_slowpath+0x81/0x610 kernel/locking/mutex.c:1228 tcf_idr_check_alloc+0x29e/0x3b0 net/sched/act_api.c:556 tcf_police_init+0x34f/0x1460 net/sched/act_police.c:81 tcf_action_init_1+0x103/0x640 net/sched/act_api.c:1026 tcf_exts_validate+0x1d7/0x540 net/sched/cls_api.c:3051 rsvp_change+0x291/0x2990 net/sched/cls_rsvp.h:502 tc_new_tfilter+0x1394/0x2120 net/sched/cls_api.c:2127 rtnetlink_rcv_msg+0x80e/0xad0 net/core/rtnetlink.c:5544 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2345 ___sys_sendmsg+0xf3/0x170 net/socket.c:2399 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2432 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x4417b9 Code: e8 fc ab 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 1b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffd5ed328c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004417b9 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000006 RBP: 0000000000076ec0 R08: 00000000004002c8 R09: 00000000004002c8 R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000402560 R13: 00000000004025f0 R14: 0000000000000000 R15: 0000000000000000 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.607 msecs --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
