* [syzbot] [net?] WARNING in rcu_note_context_switch (5)
@ 2025-12-26 16:54 syzbot
2026-07-05 6:26 ` syzbot
0 siblings, 1 reply; 2+ messages in thread
From: syzbot @ 2025-12-26 16:54 UTC (permalink / raw)
To: davem, edumazet, horms, kuba, linux-kernel, netdev, pabeni,
syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: 9448598b22c5 Linux 6.19-rc2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11423b1a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a11e0f726bfb6765
dashboard link: https://syzkaller.appspot.com/bug?extid=84d4a405ed798b40c96d
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-9448598b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e6328e25c1c8/vmlinux-9448598b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d1590b31d26d/bzImage-9448598b.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+84d4a405ed798b40c96d@syzkaller.appspotmail.com
------------[ cut here ]------------
Voluntary context switch within RCU read-side critical section!
WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0x104/0x1de0 kernel/rcu/tree_plugin.h:332, CPU#0: syz.2.13843/20505
Modules linked in:
CPU: 0 UID: 0 PID: 20505 Comm: syz.2.13843 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:rcu_note_context_switch+0x104/0x1de0 kernel/rcu/tree_plugin.h:332
Code: 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 bb 10 00 00 8b 85 84 04 00 00 85 c0 7e 0c 48 8d 3d 9c 94 e7 0e <67> 48 0f b9 3a 65 48 8b 2d 57 0e 0e 12 48 8d bd 84 04 00 00 48 b8
RSP: 0018:ffffc9000410f028 EFLAGS: 00010002
RAX: 0000000000000001 RBX: ffff88806a43bc40 RCX: ffffffff81a41b2f
RDX: 0000000000000000 RSI: ffffffff8bf2b380 RDI: ffffffff908c3650
RBP: ffff888054ce24c0 R08: 0000000000000000 R09: fffffbfff211169a
R10: ffffffff9088b4d7 R11: ffff888054ce2ff0 R12: 0000000000000000
R13: ffff888054ce24c0 R14: ffffffff9088e574 R15: ffff88806a43ac80
FS: 00007f883fff66c0(0000) GS:ffff8880d68f5000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000004a53a000 CR4: 0000000000352ef0
Call Trace:
<TASK>
__schedule+0x2dc/0x6150 kernel/sched/core.c:6748
__schedule_loop kernel/sched/core.c:6945 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:6960
netlink_broadcast_filtered+0x96d/0xf90 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+0x9e/0x220 net/netlink/af_netlink.c:2593
__ip6_del_rt_siblings net/ipv6/route.c:4056 [inline]
ip6_route_del+0x115c/0x1d70 net/ipv6/route.c:4196
inet6_rtm_delroute+0x27c/0x3b0 net/ipv6/route.c:5629
rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6958
netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0xa5d/0xc30 net/socket.c:2592
___sys_sendmsg+0x134/0x1d0 net/socket.c:2646
__sys_sendmsg+0x16d/0x220 net/socket.c:2678
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8841d8f7c9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f883fff6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8841fe5fa0 RCX: 00007f8841d8f7c9
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000003
RBP: 00007f8841e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8841fe6038 R14: 00007f8841fe5fa0 R15: 00007fffea27ccb8
</TASK>
----------------
Code disassembly (best guess):
0: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx
4: 48 89 f8 mov %rdi,%rax
7: 83 e0 07 and $0x7,%eax
a: 83 c0 03 add $0x3,%eax
d: 38 d0 cmp %dl,%al
f: 7c 08 jl 0x19
11: 84 d2 test %dl,%dl
13: 0f 85 bb 10 00 00 jne 0x10d4
19: 8b 85 84 04 00 00 mov 0x484(%rbp),%eax
1f: 85 c0 test %eax,%eax
21: 7e 0c jle 0x2f
23: 48 8d 3d 9c 94 e7 0e lea 0xee7949c(%rip),%rdi # 0xee794c6
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 65 48 8b 2d 57 0e 0e mov %gs:0x120e0e57(%rip),%rbp # 0x120e0e8e
36: 12
37: 48 8d bd 84 04 00 00 lea 0x484(%rbp),%rdi
3e: 48 rex.W
3f: b8 .byte 0xb8
---
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@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [syzbot] [net?] WARNING in rcu_note_context_switch (5)
2025-12-26 16:54 [syzbot] [net?] WARNING in rcu_note_context_switch (5) syzbot
@ 2026-07-05 6:26 ` syzbot
0 siblings, 0 replies; 2+ messages in thread
From: syzbot @ 2026-07-05 6:26 UTC (permalink / raw)
To: davem, edumazet, horms, kuba, linux-kernel, netdev, pabeni,
syzkaller-bugs
syzbot has found a reproducer for the following issue on:
HEAD commit: b73bc9ca3686 Merge tag 'nf-next-26-07-02' of https://git.k..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1043ef19580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5c4196ba0e33631d
dashboard link: https://syzkaller.appspot.com/bug?extid=84d4a405ed798b40c96d
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11d07719580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1443ef19580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b7f8c662a498/disk-b73bc9ca.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d3ffbd688a32/vmlinux-b73bc9ca.xz
kernel image: https://storage.googleapis.com/syzbot-assets/235149e2b678/bzImage-b73bc9ca.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+84d4a405ed798b40c96d@syzkaller.appspotmail.com
------------[ cut here ]------------
Voluntary context switch within RCU read-side critical section!
WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0xc58/0xef0 kernel/rcu/tree_plugin.h:332, CPU#1: syz.0.17/5817
Modules linked in:
CPU: 1 UID: 0 PID: 5817 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:rcu_note_context_switch+0xc58/0xef0 kernel/rcu/tree_plugin.h:332
Code: 00 41 c6 45 00 00 48 8b 3d 35 15 ab 0e 48 81 c4 a8 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d e9 af 60 ff ff 48 8d 3d c8 d6 ae 0e <67> 48 0f b9 3a e9 6f f4 ff ff 90 0f 0b 90 45 84 e4 0f 84 3e f4 ff
RSP: 0018:ffffc90002eced20 EFLAGS: 00010002
RAX: 0000000000000000 RBX: ffff888030d80000 RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8c4bd260 RDI: ffffffff905ad640
RBP: dffffc0000000000 R08: ffffffff905767f7 R09: 1ffffffff20aecfe
R10: dffffc0000000000 R11: fffffbfff20aecff R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880b873c180 R15: ffff888030d804c4
FS: 000055557f679500(0000) GS:ffff888125060000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff0e1073780 CR3: 0000000022684000 CR4: 00000000003526f0
Call Trace:
<TASK>
__schedule+0x2e9/0x56c0 kernel/sched/core.c:7088
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7326
netlink_broadcast_filtered+0xe53/0xea0 net/netlink/af_netlink.c:1553
nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
nlmsg_multicast include/net/netlink.h:1184 [inline]
nlmsg_notify+0xe3/0x1a0 net/netlink/af_netlink.c:2599
__ip6_del_rt_siblings+0x5ed/0x7d0 net/ipv6/route.c:4080
ip6_route_del+0x104f/0x1100 net/ipv6/route.c:4220
inet6_rtm_delroute+0x5d7/0x6d0 net/ipv6/route.c:5657
rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7076
netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
__sock_sendmsg net/socket.c:790 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2684
___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
__sys_sendmsg net/socket.c:2770 [inline]
__do_sys_sendmsg net/socket.c:2775 [inline]
__se_sys_sendmsg net/socket.c:2773 [inline]
__x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff0e119de59
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:00007ffd842e7d98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ff0e1425fa0 RCX: 00007ff0e119de59
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007ff0e1233e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff0e1425fac R14: 00007ff0e1425fa0 R15: 00007ff0e1425fa0
</TASK>
----------------
Code disassembly (best guess):
0: 00 41 c6 add %al,-0x3a(%rcx)
3: 45 00 00 add %r8b,(%r8)
6: 48 8b 3d 35 15 ab 0e mov 0xeab1535(%rip),%rdi # 0xeab1542
d: 48 81 c4 a8 00 00 00 add $0xa8,%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 af 60 ff ff jmp 0xffff60d2
23: 48 8d 3d c8 d6 ae 0e lea 0xeaed6c8(%rip),%rdi # 0xeaed6f2
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: e9 6f f4 ff ff jmp 0xfffff4a3
34: 90 nop
35: 0f 0b ud2
37: 90 nop
38: 45 84 e4 test %r12b,%r12b
3b: 0f .byte 0xf
3c: 84 3e test %bh,(%rsi)
3e: f4 hlt
3f: ff .byte 0xff
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2026-07-05 6:26 UTC | newest]
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2025-12-26 16:54 [syzbot] [net?] WARNING in rcu_note_context_switch (5) syzbot
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