BUG: soft lockup in x64_sys_call

Status: upstream: reported C repro on 2026/02/15 08:06
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+7f25199cde1fab5dc10d@syzkaller.appspotmail.com
First crash: 530d, last: 23d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/02/15 lts (merge base) e50b81c50fcb C [report] BUG: soft lockup in sock_setsockopt
2026/02/15 upstream (ToT) ca4ee40bf13d C [report] BUG: soft lockup in x64_sys_call
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 BUG: soft lockup in x64_sys_call origin:upstream 1 C 34 29d 699d 0/2 upstream: reported C repro on 2024/08/25 04:51
android-6-12 BUG: soft lockup in x64_sys_call 1 23 262d 396d 0/1 auto-obsoleted due to no activity on 2026/01/28 18:33
android-6-12 BUG: soft lockup in x64_sys_call (2) origin:upstream 1 C 6 151d 150d 1/1 fixed on 2026/03/04 11:24
upstream INFO: rcu detected stall in x64_sys_call prio:low mm 1 C error 583 3h28m 683d 0/29 upstream: reported C repro on 2024/09/09 20:48
linux-5.15 INFO: rcu detected stall in x64_sys_call 1 1 757d 757d 0/3 auto-obsoleted due to no activity on 2024/10/06 02:18
linux-6.1 INFO: rcu detected stall in x64_sys_call 1 1 448d 448d 0/3 auto-obsoleted due to no activity on 2025/08/11 06:03
▶ ▼ Last patch testing requests (6)
Created Duration User Patch Repo Result
2026/07/17 14:11 16m retest repro android14-6.1 log
2026/07/17 14:11 14m retest repro android14-6.1 log
2026/05/31 02:34 16m retest repro android14-6.1 log
2026/05/31 02:34 13m retest repro android14-6.1 log
2026/04/02 12:52 28m retest repro android14-6.1 report log
2026/04/02 10:06 3h03m retest repro android14-6.1 report log
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2026/01/22 08:50 0m bisect fix android14-6.1 error job log
2025/06/03 21:27 1h30m bisect fix android14-6.1 OK (0) job log log

Sample crash report:
watchdog: BUG: soft lockup - CPU#0 stuck for 246s! [syz.2.98:618]
Modules linked in:
CPU: 0 PID: 618 Comm: syz.2.98 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x105/0x150 arch/x86/kernel/kvm.c:1064
Code: 1b 33 04 f4 eb 87 fa 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 3f 0f b6 07 40 38 f0 75 10 66 90 0f 00 2d cd 1b 33 04 fb f4 <e9> 5e ff ff ff fb e9 58 ff ff ff e8 eb 20 c5 03 89 f9 80 e1 07 38
RSP: 0018:ffffc90000fdf660 EFLAGS: 00000246
RAX: 0000000000000003 RBX: ffff888114e88a98 RCX: ffffffff85012019
RDX: dffffc0000000000 RSI: 0000000000000003 RDI: ffff888114e88a98
RBP: ffffc90000fdf6f0 R08: ffff888114e88a98 R09: 1ffff110229d1153
R10: dffffc0000000000 R11: ffffed10229d1154 R12: 1ffff110229d1153
R13: ffff8881f6e38cd4 R14: dffffc0000000000 R15: 1ffff920001fbecc
FS:  00007f7c888fc6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 000000011c2a9000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 pv_wait arch/x86/include/asm/paravirt.h:603 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
 __pv_queued_spin_lock_slowpath+0x687/0xc40 kernel/locking/qspinlock.c:511
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock include/linux/spinlock.h:187 [inline]
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:127 [inline]
 _raw_spin_lock_bh+0xe4/0xf0 kernel/locking/spinlock.c:178
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 lock_sock_nested+0x90/0x290 net/core/sock.c:3515
 lock_sock include/net/sock.h:1818 [inline]
 tipc_sendstream+0x47/0x70 net/tipc/socket.c:1549
 sock_sendmsg_nosec net/socket.c:716 [inline]
 __sock_sendmsg net/socket.c:728 [inline]
 ____sys_sendmsg+0x5fb/0x9c0 net/socket.c:2508
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2562
 __sys_sendmsg net/socket.c:2591 [inline]
 __do_sys_sendmsg net/socket.c:2600 [inline]
 __se_sys_sendmsg net/socket.c:2598 [inline]
 __x64_sys_sendmsg+0x20d/0x2e0 net/socket.c:2598
 x64_sys_call+0x171/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7c8799de59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7c888fc028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f7c87c25fa0 RCX: 00007f7c8799de59
RDX: 0000000000000000 RSI: 0000200000003280 RDI: 0000000000000004
RBP: 00007f7c87a33e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7c87c26038 R14: 00007f7c87c25fa0 R15: 00007ffec4d11938
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 619 Comm: syz.2.98 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:msg_word net/tipc/msg.h:207 [inline]
RIP: 0010:msg_destport net/tipc/msg.h:601 [inline]
RIP: 0010:tipc_skb_peek_port net/tipc/msg.h:1227 [inline]
RIP: 0010:tipc_sk_rcv+0x2bb/0x2c20 net/tipc/socket.c:2493
Code: 00 00 00 4c 89 f8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ff e8 d7 47 dd fc 4d 8b 3f 49 83 c7 14 4c 89 f8 48 c1 e8 03 0f b6 04 18 <84> c0 0f 85 ee 1a 00 00 45 8b 3f 41 0f cf 45 85 f6 0f 84 d7 00 00
RSP: 0018:ffffc9000122e7c0 EFLAGS: 00000a07
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffff88811c38bcc0 RSI: 000000001e24e20e RDI: 0000000000000000
RBP: ffffc9000122ea30 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000245ce8 R12: ffff8881138dac00
R13: ffff888114e88a80 R14: 000000001e24e20e R15: ffff888118c3f0c4
FS:  00007f7c888db6c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7c888daff8 CR3: 000000011c2a9000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tipc_node_xmit+0x36f/0xd80 net/tipc/node.c:1703
 tipc_node_xmit_skb net/tipc/node.c:1768 [inline]
 tipc_node_distr_xmit+0x277/0x390 net/tipc/node.c:1783
 tipc_sk_rcv+0x1a04/0x2c20 net/tipc/socket.c:2503
 tipc_node_xmit+0x36f/0xd80 net/tipc/node.c:1703
 tipc_sk_push_backlog+0x4d3/0x7b0 net/tipc/socket.c:1316
 tipc_sk_conn_proto_rcv net/tipc/socket.c:1370 [inline]
 tipc_sk_proto_rcv+0x9c3/0x15b0 net/tipc/socket.c:2158
 tipc_sk_filter_rcv+0x2e22/0x3010 net/tipc/socket.c:2354
 tipc_sk_enqueue net/tipc/socket.c:2447 [inline]
 tipc_sk_rcv+0x7e7/0x2c20 net/tipc/socket.c:2499
 tipc_node_xmit+0x36f/0xd80 net/tipc/node.c:1703
 tipc_node_xmit_skb net/tipc/node.c:1768 [inline]
 tipc_node_distr_xmit+0x277/0x390 net/tipc/node.c:1783
 tipc_sk_backlog_rcv+0x174/0x220 net/tipc/socket.c:2414
 sk_backlog_rcv include/net/sock.h:1150 [inline]
 __release_sock+0x154/0x380 net/core/sock.c:2951
 release_sock net/core/sock.c:3527 [inline]
 sockopt_release_sock+0x95/0x1f0 net/core/sock.c:1067
 sk_setsockopt+0x1929/0x26b0 net/core/sock.c:1545
 sock_setsockopt+0x5a/0x70 net/core/sock.c:1552
 __sys_setsockopt+0x269/0x4e0 net/socket.c:2273
 __do_sys_setsockopt net/socket.c:2288 [inline]
 __se_sys_setsockopt net/socket.c:2285 [inline]
 __x64_sys_setsockopt+0xbf/0xd0 net/socket.c:2285
 x64_sys_call+0x124/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:55
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7c8799de59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7c888db028 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f7c87c26090 RCX: 00007f7c8799de59
RDX: 0000000000000021 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 00007f7c87a33e6f R08: 0000000000000004 R09: 0000000000000000
R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7c87c26128 R14: 00007f7c87c26090 R15: 00007ffec4d11938
 </TASK>

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/02 12:35 android14-6.1 cf4093a4ac64 27192279 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1 BUG: soft lockup in x64_sys_call
2026/02/15 07:56 android14-6.1 edbe3e111301 1e62d198 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1 BUG: soft lockup in x64_sys_call
2025/08/05 00:05 android14-6.1 3b4ff5af8d36 f5bcc8dc .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-android-6-1 BUG: soft lockup in x64_sys_call
2025/02/10 08:38 android14-6.1 1ac09f5c0571 ef44b750 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-android-6-1 BUG: soft lockup in x64_sys_call
2026/06/25 02:43 android14-6.1 83f1262811ad 302586aa .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf BUG: soft lockup in x64_sys_call
2026/06/15 23:10 android14-6.1 f17c14b8ada7 50bb0618 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf BUG: soft lockup in x64_sys_call
2025/12/15 09:52 android14-6.1 6f1c2f8fd8c8 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf BUG: soft lockup in x64_sys_call
2025/11/30 15:35 android14-6.1 a92da54b7708 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf BUG: soft lockup in x64_sys_call
2025/09/30 06:13 android14-6.1 f6787ec80e17 86341da6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf BUG: soft lockup in x64_sys_call
2025/06/21 22:21 android14-6.1 f6c21bc9a693 d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf BUG: soft lockup in x64_sys_call
* Struck through repros no longer work on HEAD.