bisecting fixing commit since 2034d6f0838e465dd8f120c4e946d8444b4bb5df building syzkaller on 6a81331a1d4c744da9204d02ec88d558f7eea9c9 testing commit 2034d6f0838e465dd8f120c4e946d8444b4bb5df with gcc (GCC) 8.4.1 20210217 kernel signature: 5e53b616762352c14477f06c65f77c4694fd97b0aa8190eab281dd772b60a762 run #0: crashed: BUG: soft lockup in netlink_sendmsg run #1: crashed: BUG: soft lockup in netlink_sendmsg run #2: crashed: BUG: soft lockup in netlink_sendmsg run #3: crashed: BUG: soft lockup in netlink_sendmsg run #4: crashed: BUG: soft lockup in netlink_sendmsg run #5: crashed: BUG: soft lockup in netlink_sendmsg run #6: crashed: BUG: soft lockup in netlink_sendmsg run #7: crashed: BUG: soft lockup in netlink_sendmsg run #8: crashed: BUG: soft lockup in netlink_sendmsg run #9: crashed: BUG: soft lockup in netlink_sendmsg run #10: crashed: BUG: soft lockup in netlink_sendmsg run #11: crashed: BUG: soft lockup in netlink_sendmsg run #12: crashed: BUG: soft lockup in netlink_sendmsg run #13: crashed: BUG: soft lockup in netlink_sendmsg run #14: crashed: BUG: soft lockup in netlink_sendmsg run #15: crashed: BUG: soft lockup in netlink_sendmsg run #16: crashed: BUG: soft lockup in netlink_sendmsg run #17: crashed: BUG: soft lockup in netlink_sendmsg run #18: crashed: BUG: soft lockup in netlink_sendmsg run #19: crashed: BUG: soft lockup in addrconf_rs_timer testing current HEAD 9f84340f012ee60c12aacc03662bcdd67419a31a testing commit 9f84340f012ee60c12aacc03662bcdd67419a31a with gcc (GCC) 8.4.1 20210217 kernel signature: 17d5cbfa796d41a687d4701b5a9a7a7bf5fde2f9b00e2287bae6862781849a60 run #0: crashed: BUG: soft lockup in netlink_sendmsg run #1: crashed: BUG: soft lockup in netlink_sendmsg run #2: crashed: BUG: soft lockup in netlink_sendmsg run #3: crashed: BUG: soft lockup in netlink_sendmsg run #4: crashed: BUG: soft lockup in netlink_sendmsg run #5: crashed: BUG: soft lockup in addrconf_rs_timer run #6: crashed: BUG: soft lockup in netlink_sendmsg run #7: crashed: BUG: soft lockup in netlink_sendmsg run #8: crashed: BUG: soft lockup in netlink_sendmsg run #9: crashed: BUG: soft lockup in netlink_sendmsg revisions tested: 2, total time: 23m54.476810184s (build: 16m12.049857539s, test: 7m20.809857564s) the crash still happens on HEAD commit msg: Linux 4.19.196 crash: BUG: soft lockup in netlink_sendmsg wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [syz-executor.4:10085] Modules linked in: irq event stamp: 10857 hardirqs last enabled at (10856): [] kvm_wait arch/x86/kernel/kvm.c:799 [inline] hardirqs last enabled at (10856): [] kvm_wait+0x163/0x230 arch/x86/kernel/kvm.c:779 hardirqs last disabled at (10857): [] trace_hardirqs_off_thunk+0x1a/0x1c softirqs last enabled at (84): [] spin_unlock_bh include/linux/spinlock.h:374 [inline] softirqs last enabled at (84): [] release_sock+0x11f/0x180 net/core/sock.c:2892 softirqs last disabled at (92): [] __dev_queue_xmit+0x20b/0x2900 net/core/dev.c:3773 CPU: 0 PID: 10085 Comm: syz-executor.4 Not tainted 4.19.196-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:61 Code: 11 ff ff ff 4c 89 e7 e8 fc f9 e6 f9 eb 97 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 e9 07 00 00 00 0f 00 2d 30 46 62 00 fb f4 <5d> c3 66 66 2e 0f 1f 84 00 00 00 00 00 90 55 48 89 e5 e9 07 00 00 RSP: 0018:ffff88809623f4f0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffff8880943a16e8 RCX: 1ffff11016488d7f RDX: 1ffffffff132249c RSI: ffff8880b2446bd8 RDI: ffffffff899124e0 RBP: ffff88809623f4f0 R08: ffff8880b2446bf8 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000003 R13: 0000000000000286 R14: 0000000000000000 R15: 0000000000000001 FS: 00007fec1d5ca700(0000) GS:ffff8880ba200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fec1d5a9718 CR3: 00000000970c1000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] kvm_wait arch/x86/kernel/kvm.c:799 [inline] kvm_wait+0x194/0x230 arch/x86/kernel/kvm.c:779 pv_wait arch/x86/include/asm/paravirt.h:689 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:471 [inline] __pv_queued_spin_lock_slowpath+0x90d/0xc00 kernel/locking/qspinlock.c:474 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:679 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:53 [inline] queued_spin_lock include/asm-generic/qspinlock.h:88 [inline] do_raw_spin_lock+0x1a5/0x240 kernel/locking/spinlock_debug.c:113 __raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_lock+0x35/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __dev_xmit_skb net/core/dev.c:3469 [inline] __dev_queue_xmit+0x100b/0x2900 net/core/dev.c:3807 dev_queue_xmit+0xb/0x10 net/core/dev.c:3871 __netlink_deliver_tap_skb net/netlink/af_netlink.c:303 [inline] __netlink_deliver_tap net/netlink/af_netlink.c:321 [inline] netlink_deliver_tap+0x77e/0xb00 net/netlink/af_netlink.c:334 netlink_deliver_tap_kernel net/netlink/af_netlink.c:343 [inline] netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x412/0x660 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: 0033:0x466459 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:00007fec1d5ca188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000466459 RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000003 RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008 R13: 00007ffde6a8a16f R14: 00007fec1d5ca300 R15: 0000000000022000 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 10080 Comm: syz-executor.4 Not tainted 4.19.196-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:cake_heap_get_backlog net/sched/sch_cake.c:1369 [inline] RIP: 0010:cake_heapify+0x158/0x300 net/sched/sch_cake.c:1383 Code: 28 49 89 f8 41 83 e0 07 41 83 c0 01 45 38 c8 7c 09 45 84 c9 0f 85 83 01 00 00 48 83 c3 08 45 0f b6 64 5f 08 41 0f b7 5c 5f 08 <41> 83 e4 07 4d 69 e4 d8 98 01 00 66 c1 eb 03 4d 03 67 10 81 e3 ff RSP: 0018:ffff88808def74b8 EFLAGS: 00000202 RAX: 00000000000010a6 RBX: 00000000000010a5 RCX: 0000000000000017 RDX: 0000000000000852 RSI: 00000000000010a5 RDI: ffff8880943a39e2 RBP: ffff88808def74f0 R08: 0000000000000003 R09: 0000000000000000 R10: fffffbfff15df409 R11: 000000009675e8a0 R12: 00000000000000a5 R13: dffffc0000000000 R14: 0000000000000852 R15: ffff8880943a1880 FS: 00007fec1d5eb700(0000) GS:ffff8880ba300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000002685708 CR3: 00000000970c1000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: cake_drop net/sched/sch_cake.c:1472 [inline] cake_enqueue+0x1186/0x3b00 net/sched/sch_cake.c:1848 __dev_xmit_skb net/core/dev.c:3494 [inline] __dev_queue_xmit+0x1098/0x2900 net/core/dev.c:3807 dev_queue_xmit+0xb/0x10 net/core/dev.c:3871 __netlink_deliver_tap_skb net/netlink/af_netlink.c:303 [inline] __netlink_deliver_tap net/netlink/af_netlink.c:321 [inline] netlink_deliver_tap+0x77e/0xb00 net/netlink/af_netlink.c:334 netlink_deliver_tap_kernel net/netlink/af_netlink.c:343 [inline] netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x412/0x660 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: 0033:0x466459 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:00007fec1d5eb188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459 RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 0000000000000005 RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffde6a8a16f R14: 00007fec1d5eb300 R15: 0000000000022000