Hello, syzbot found the following issue on: HEAD commit: c7d102232649 Merge tag 'net-5.14-rc4' of git://git.kernel... git tree: net console output: https://syzkaller.appspot.com/x/log.txt?x=131efc8a300000 kernel config: https://syzkaller.appspot.com/x/.config?x=bfd78f4abd4edaa6 dashboard link: https://syzkaller.appspot.com/bug?extid=a9b681dcbc06eb2bca04 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13e91804300000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1508bb1e300000 The issue was bisected to: commit 997acaf6b4b59c6a9c259740312a69ea549cc684 Author: Mark Rutland <mark.rutland@xxxxxxx> Date: Mon Jan 11 15:37:07 2021 +0000 lockdep: report broken irq restoration bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=102f551a300000 final oops: https://syzkaller.appspot.com/x/report.txt?x=122f551a300000 console output: https://syzkaller.appspot.com/x/log.txt?x=142f551a300000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+a9b681dcbc06eb2bca04@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration") INFO: task khugepaged:1663 blocked for more than 143 seconds. Not tainted 5.14.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:khugepaged state:D stack:28464 pid: 1663 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4683 [inline] __schedule+0x93a/0x26f0 kernel/sched/core.c:5940 schedule+0xd3/0x270 kernel/sched/core.c:6019 schedule_timeout+0x1db/0x2a0 kernel/time/timer.c:1855 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x176/0x280 kernel/sched/completion.c:138 __flush_work+0x50e/0xad0 kernel/workqueue.c:3053 __lru_add_drain_all+0x3fd/0x760 mm/swap.c:842 khugepaged_do_scan mm/khugepaged.c:2214 [inline] khugepaged+0x10f/0x5590 mm/khugepaged.c:2275 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Showing all locks held in the system: 1 lock held by khungtaskd/1647: #0: ffffffff8b97ba40 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6446 1 lock held by khugepaged/1663: #0: ffffffff8ba5e948 (lock#6){+.+.}-{3:3}, at: __lru_add_drain_all+0x65/0x760 mm/swap.c:791 1 lock held by in:imklog/8274: #0: ffff88801b6b4ff0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:974 3 locks held by kworker/1:4/8673: 3 locks held by kworker/1:5/8674: 2 locks held by syz-executor764/31172: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1647 Comm: khungtaskd Not tainted 5.14.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 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:210 [inline] watchdog+0xd0a/0xfc0 kernel/hung_task.c:295 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.14.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__find_rr_leaf+0x2d4/0xd20 net/ipv6/route.c:794 Code: 08 0f 84 58 01 00 00 e8 aa 3d a0 f9 48 83 3c 24 00 74 43 e8 9e 3d a0 f9 48 8d bb 80 00 00 00 48 89 f8 48 c1 e8 03 0f b6 04 28 <84> c0 74 08 3c 03 0f 8e 49 08 00 00 44 8b a3 80 00 00 00 44 8b 74 RSP: 0018:ffffc90000d97508 EFLAGS: 00000a06 RAX: 0000000000000000 RBX: ffff88804f143400 RCX: 0000000000000100 RDX: ffff888010a7d4c0 RSI: ffffffff87d55dc2 RDI: ffff88804f143480 RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff87d55d8a R11: 0000000000000000 R12: 0000000000000001 R13: ffffc90000d977f0 R14: 0000000000000000 R15: ffff88804f142aa0 FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000200000c0 CR3: 000000001ff23000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: find_rr_leaf net/ipv6/route.c:846 [inline] rt6_select net/ipv6/route.c:890 [inline] fib6_table_lookup+0x649/0xa20 net/ipv6/route.c:2174 ip6_pol_route+0x1c5/0x11d0 net/ipv6/route.c:2210 pol_lookup_func include/net/ip6_fib.h:579 [inline] fib6_rule_lookup+0x111/0x6f0 net/ipv6/fib6_rules.c:115 ip6_route_input_lookup net/ipv6/route.c:2280 [inline] ip6_route_input+0x63c/0xb30 net/ipv6/route.c:2576 ip6_rcv_finish_core.constprop.0.isra.0+0x168/0x570 net/ipv6/ip6_input.c:63 ip6_rcv_finish net/ipv6/ip6_input.c:74 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ipv6_rcv+0x229/0x3c0 net/ipv6/ip6_input.c:297 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5498 __netif_receive_skb+0x24/0x1b0 net/core/dev.c:5612 process_backlog+0x2a5/0x6c0 net/core/dev.c:6492 __napi_poll+0xaf/0x440 net/core/dev.c:7047 napi_poll net/core/dev.c:7114 [inline] net_rx_action+0x801/0xb40 net/core/dev.c:7201 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 run_ksoftirqd kernel/softirq.c:920 [inline] run_ksoftirqd+0x2d/0x60 kernel/softirq.c:912 smpboot_thread_fn+0x645/0x9c0 kernel/smpboot.c:164 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 --- 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
