syzbot


WARNING in rcu_note_context_switch (5)

Status: upstream: reported on 2025/12/26 16:54
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+84d4a405ed798b40c96d@syzkaller.appspotmail.com
First crash: 120d, last: 21h17m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
44718797-da22-4c3b-ad1d-b8d466f76b7b repro WARNING in rcu_note_context_switch (5) 2026/03/07 20:14 2026/03/07 20:14 2026/03/07 20:25 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [net?] WARNING in rcu_note_context_switch (5) 0 (1) 2025/12/26 16:54
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in rcu_note_context_switch (4) net -1 1 293d 293d 0/29 closed as invalid on 2025/09/01 08:35
upstream WARNING in rcu_note_context_switch (3) net -1 1 526d 522d 0/29 auto-obsoleted due to no activity on 2025/02/18 17:10
upstream WARNING in rcu_note_context_switch kernel -1 C done 1 2394d 2394d 13/29 fixed on 2019/10/15 23:40
upstream WARNING in rcu_note_context_switch (2) rcu -1 C 13 642d 639d 0/29 auto-obsoleted due to no activity on 2024/09/25 21:55

Sample crash report:
------------[ cut here ]------------
Voluntary context switch within RCU read-side critical section!
WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0xcac/0xf40 kernel/rcu/tree_plugin.h:332, CPU#0: syz.1.2818/15659
Modules linked in:
CPU: 0 UID: 0 PID: 15659 Comm: syz.1.2818 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:rcu_note_context_switch+0xcac/0xf40 kernel/rcu/tree_plugin.h:332
Code: 00 41 c6 45 00 00 48 8b 3d 71 6b 87 0e 48 81 c4 b8 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d e9 8b 60 ff ff 48 8d 3d 24 4f 8b 0e <67> 48 0f b9 3a e9 1b f4 ff ff 90 0f 0b 90 45 84 e4 0f 84 ea f3 ff
RSP: 0018:ffffc90003aa6cd0 EFLAGS: 00010002
RAX: 0000000000000000 RBX: ffff888032728000 RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8c289440 RDI: ffffffff9036e520
RBP: dffffc0000000000 R08: ffffffff903353f7 R09: 1ffffffff2066a7e
R10: dffffc0000000000 R11: fffffbfff2066a7f R12: 0000000000000000
R13: ffff888032728000 R14: ffff8880b863be80 R15: ffff8880327284c4
FS:  00007fd8c9df66c0(0000) GS:ffff88812521e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000060000 CR3: 0000000050dda000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000001000 DR2: 0000000000000000
DR3: 0000000000000400 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __schedule+0x2e6/0x5680 kernel/sched/core.c:7043
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7282
 netlink_broadcast_filtered+0xe61/0xeb0 net/netlink/af_netlink.c:1547
 nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
 nlmsg_multicast include/net/netlink.h:1184 [inline]
 nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2593
 __ip6_del_rt_siblings+0x5fc/0x7d0 net/ipv6/route.c:4071
 ip6_route_del+0x1047/0x1100 net/ipv6/route.c:4211
 inet6_rtm_delroute+0x5d7/0x6d0 net/ipv6/route.c:5644
 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
 __sys_sendmsg net/socket.c:2784 [inline]
 __do_sys_sendmsg net/socket.c:2789 [inline]
 __se_sys_sendmsg net/socket.c:2787 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd8cbb9c819
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:00007fd8c9df6028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd8cbe16180 RCX: 00007fd8cbb9c819
RDX: 0000000000000000 RSI: 00002000000004c0 RDI: 000000000000000d
RBP: 00007fd8cbc32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd8cbe16218 R14: 00007fd8cbe16180 R15: 00007fd8cbf3fa48
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 41 c6             	add    %al,-0x3a(%rcx)
   3:	45 00 00             	add    %r8b,(%r8)
   6:	48 8b 3d 71 6b 87 0e 	mov    0xe876b71(%rip),%rdi        # 0xe876b7e
   d:	48 81 c4 b8 00 00 00 	add    $0xb8,%rsp
  14:	5b                   	pop    %rbx
  15:	41 5c                	pop    %r12
  17:	41 5d                	pop    %r13
  19:	41 5e                	pop    %r14
  1b:	41 5f                	pop    %r15
  1d:	5d                   	pop    %rbp
  1e:	e9 8b 60 ff ff       	jmp    0xffff60ae
  23:	48 8d 3d 24 4f 8b 0e 	lea    0xe8b4f24(%rip),%rdi        # 0xe8b4f4e
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 1b f4 ff ff       	jmp    0xfffff44f
  34:	90                   	nop
  35:	0f 0b                	ud2
  37:	90                   	nop
  38:	45 84 e4             	test   %r12b,%r12b
  3b:	0f                   	.byte 0xf
  3c:	84 ea                	test   %ch,%dl
  3e:	f3                   	repz
  3f:	ff                   	.byte 0xff

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/20 19:43 upstream c1f49dea2b8f e65da4ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in rcu_note_context_switch
2026/02/22 18:56 upstream 32a92f8c8932 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in rcu_note_context_switch
2026/02/25 15:34 upstream 7dff99b35460 c162cde9 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in rcu_note_context_switch
2025/12/22 16:43 upstream 9448598b22c5 d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in rcu_note_context_switch
* Struck through repros no longer work on HEAD.