syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5797/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=10645, q=354 ncpus=2)
task:syz-executor278 state:R  running task     stack:21736 pid:5797  ppid:5793   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_notrace+0xdd/0x110 kernel/sched/core.c:6960
 preempt_schedule_notrace_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:46
 rcu_is_watching+0x7a/0xb0 kernel/rcu/tree.c:701
 trace_notifier_run include/trace/events/notifier.h:59 [inline]
 notifier_call_chain+0x158/0x380 kernel/notifier.c:92
 atomic_notifier_call_chain+0xda/0x180 kernel/notifier.c:231
 ipv6_add_addr+0xdde/0x10d0 net/ipv6/addrconf.c:1189
 addrconf_add_linklocal+0x273/0x6d0 net/ipv6/addrconf.c:3302
 addrconf_addr_gen+0x50e/0x620 net/ipv6/addrconf.c:3433
 addrconf_init_auto_addrs+0x77b/0xb20 net/ipv6/addrconf.c:-1
 addrconf_notify+0xb62/0x1010 net/ipv6/addrconf.c:3730
 notifier_call_chain+0x197/0x380 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2077 [inline]
 call_netdevice_notifiers net/core/dev.c:2091 [inline]
 __dev_notify_flags+0x1aa/0x310 net/core/dev.c:8762
 dev_change_flags+0xe8/0x1a0 net/core/dev.c:8800
 do_setlink+0xc58/0x4130 net/core/rtnetlink.c:2909
 __rtnl_newlink net/core/rtnetlink.c:3707 [inline]
 rtnl_newlink+0x17da/0x20a0 net/core/rtnetlink.c:3754
 rtnetlink_rcv_msg+0x869/0xfa0 net/core/rtnetlink.c:6476
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x4a9/0x6b0 net/socket.c:2200
 __do_sys_sendto net/socket.c:2212 [inline]
 __se_sys_sendto net/socket.c:2208 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2208
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f258c04949e
RSP: 002b:00007ffed37b4b78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000555575bd73c0 RCX: 00007f258c04949e
RDX: 000000000000002c RSI: 00007f258c0cebd0 RDI: 0000000000000003
RBP: 0000000000000003 R08: 00007ffed37b4bf4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f258c0cebd0 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10560 jiffies! g10645 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:26568 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 5835 Comm: syz-executor278 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:__syscall_enter_from_user_work kernel/entry/common.c:97 [inline]
RIP: 0010:syscall_enter_from_user_mode+0x2e/0x80 kernel/entry/common.c:118
Code: 41 56 53 48 89 f3 49 89 fe 48 8b 7c 24 10 e8 e9 fa ff ff 66 90 66 90 e8 e0 3c 05 f7 e8 9b 3c 05 f7 fb 65 48 8b 05 12 54 7b 75 <48> 8b 70 08 40 f6 c6 3f 74 0b 4c 89 f7 5b 41 5e e9 5d 77 eb f6 48
RSP: 0018:ffffc90004a5ff08 EFLAGS: 00000286
RAX: ffff88807d443c00 RBX: 000000000000000f RCX: 4ccbf7f15941c100
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: ffffffff8b1c9c20
RBP: ffffc90004a5ff48 R08: ffffffff8e8b666f R09: 1ffffffff1d16ccd
R10: dffffc0000000000 R11: fffffbfff1d16cce R12: 0000000000000000
R13: 0000000000000000 R14: ffffc90004a5ff58 R15: 0000000000000000
FS:  0000555575bd73c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000140 CR3: 000000002fc09000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 do_syscall_64+0x28/0xb0 arch/x86/entry/common.c:72
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f258c0398e9
Code: 9b fe ff 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 0c 25
RSP: 002b:00007ffed37b4bc0 EFLAGS: 00000202 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f258c0398e9
RDX: 00007ffed37b4bc0 RSI: 00007ffed37b4cf0 RDI: 0000000000000021
RBP: 0000000000000000 R08: 00007f258c09723e R09: 00007f258c09723e
R10: 0000000000000000 R11: 0000000000000202 R12: 00007f258c097590
R13: 00007ffed37b5450 R14: 00007ffed37b5190 R15: 0000000000000000
 </TASK>
sched: RT throttling activated