bisecting fixing commit since 20b3a3dfdf6c55b50bbdc8e231a3dbf6bf965dc7 building syzkaller on 70c104a18f3d409bc6dde950b50258d3d280d99b testing commit 20b3a3dfdf6c55b50bbdc8e231a3dbf6bf965dc7 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 00c28b85c72d32d6615eacb5eda24e18485fe48a92cadb53eddd2a4b2592ade0 run #0: crashed: BUG: unable to handle kernel paging request in __alloc_skb run #1: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #2: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #3: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #4: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #5: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #6: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #7: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #8: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #9: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #10: crashed: INFO: rcu detected stall in rtnl_newlink run #11: crashed: INFO: rcu detected stall in rtnl_newlink run #12: crashed: INFO: rcu detected stall in rtnl_newlink run #13: crashed: INFO: rcu detected stall in rtnl_newlink run #14: crashed: INFO: rcu detected stall in rtnl_newlink run #15: crashed: INFO: rcu detected stall in rtnl_newlink run #16: crashed: INFO: rcu detected stall in rtnl_newlink run #17: crashed: INFO: rcu detected stall in rtnl_newlink run #18: crashed: INFO: rcu detected stall in rtnl_newlink run #19: crashed: INFO: rcu detected stall in rtnl_newlink testing current HEAD a89b48fe9308d976d9dcb2112e264d647f7efce4 testing commit a89b48fe9308d976d9dcb2112e264d647f7efce4 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 2dad15c1c9629318d0471e413f499a43387c81ec7bae8a24adbb3df3a9fef1dd run #0: crashed: BUG: unable to handle kernel paging request in __alloc_skb run #1: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #2: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #3: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #4: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #5: crashed: BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet run #6: crashed: INFO: rcu detected stall in rtnl_newlink run #7: crashed: INFO: rcu detected stall in rtnl_newlink run #8: crashed: INFO: rcu detected stall in rtnl_newlink run #9: crashed: INFO: rcu detected stall in rtnl_newlink revisions tested: 2, total time: 28m23.563373693s (build: 18m11.501739491s, test: 9m38.983503864s) the crash still happens on HEAD commit msg: Linux 4.19.199 crash: INFO: rcu detected stall in rtnl_newlink batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-....: (1 GPs behind) idle=0e6/1/0x4000000000000002 softirq=8785/8786 fqs=5250 rcu: (t=10502 jiffies g=4617 q=1015) NMI backtrace for cpu 1 CPU: 1 PID: 7139 Comm: syz-executor.1 Not tainted 4.19.199-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x17c/0x226 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.0+0x3c/0x78 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf5/0x120 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1340 print_cpu_stall kernel/rcu/tree.c:1478 [inline] check_cpu_stall kernel/rcu/tree.c:1550 [inline] __rcu_pending kernel/rcu/tree.c:3293 [inline] rcu_pending kernel/rcu/tree.c:3336 [inline] rcu_check_callbacks.cold.62+0x5b1/0xd89 kernel/rcu/tree.c:2682 update_process_times+0x2a/0x60 kernel/time/timer.c:1650 tick_sched_handle.isra.5+0x6b/0x130 kernel/time/tick-sched.c:168 tick_sched_timer+0x3c/0xf0 kernel/time/tick-sched.c:1278 __run_hrtimer kernel/time/hrtimer.c:1419 [inline] __hrtimer_run_queues+0x2fa/0xaa0 kernel/time/hrtimer.c:1481 hrtimer_interrupt+0x2e2/0x760 kernel/time/hrtimer.c:1539 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1071 [inline] smp_apic_timer_interrupt+0x114/0x540 arch/x86/kernel/apic/apic.c:1096 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894 RIP: 0010:debug_spin_unlock kernel/locking/spinlock_debug.c:100 [inline] RIP: 0010:do_raw_spin_unlock+0xcf/0x260 kernel/locking/spinlock_debug.c:134 Code: 00 00 65 48 8b 04 25 40 ee 01 00 48 39 43 10 0f 85 e7 00 00 00 4c 8d 63 08 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 27 01 00 00 65 8b 05 0a 36 b6 RSP: 0018:ffff8881d9de6b50 EFLAGS: 00000a06 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffff8881d1ecb7a0 RCX: ffffffff814b4a94 RDX: 1ffff1103a3d96f5 RSI: 0000000000000004 RDI: ffff8881d1ecb7a0 RBP: ffff8881d9de6b68 R08: ffffed103a3d96f5 R09: ffffed103a3d96f4 R10: ffffed103a3d96f4 R11: ffff8881d1ecb7a3 R12: ffff8881d1ecb7a8 R13: ffff8881d1ecb7b0 R14: ffff8881e8862498 R15: ffff8881e8a76d40 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:175 [inline] _raw_spin_unlock_bh+0x22/0x40 kernel/locking/spinlock.c:200 spin_unlock_bh include/linux/spinlock.h:374 [inline] batadv_tt_local_purge+0x1f1/0x2c0 net/batman-adv/translation-table.c:1456 batadv_tt_local_resize_to_mtu+0x87/0xf0 net/batman-adv/translation-table.c:4207 batadv_update_min_mtu net/batman-adv/hard-interface.c:637 [inline] batadv_hardif_activate_interface.part.3.cold.8+0xcb/0x313 net/batman-adv/hard-interface.c:664 batadv_hardif_activate_interface net/batman-adv/hard-interface.c:825 [inline] batadv_hardif_enable_interface+0x987/0xa40 net/batman-adv/hard-interface.c:817 batadv_softif_slave_add+0x7f/0xd0 net/batman-adv/soft-interface.c:898 do_set_master net/core/rtnetlink.c:2321 [inline] do_set_master+0x171/0x200 net/core/rtnetlink.c:2295 do_setlink+0x94c/0x2ec0 net/core/rtnetlink.c:2455 rtnl_newlink+0x975/0x1360 net/core/rtnetlink.c:3077 rtnetlink_rcv_msg+0x34f/0x950 net/core/rtnetlink.c:4782 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2457 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4800 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x443/0x660 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x667/0xc60 net/netlink/af_netlink.c:1911 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:661 ___sys_sendmsg+0x647/0x950 net/socket.c:2225 __sys_sendmsg+0xd9/0x180 net/socket.c:2263 __do_sys_sendmsg net/socket.c:2272 [inline] __se_sys_sendmsg net/socket.c:2270 [inline] __x64_sys_sendmsg+0x73/0xb0 net/socket.c:2270 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x463b49 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f9f2a415188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000055bf00 RCX: 0000000000463b49 RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000004 RBP: 00000000004ae538 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007ffe7f08507f R14: 00007f9f2a415300 R15: 0000000000022000 net_ratelimit: 6791 callbacks suppressed batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) net_ratelimit: 7024 callbacks suppressed batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224) batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)