syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P14909/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=75061, q=592 ncpus=2)
task:syz.1.1584      state:R  running task     stack:23128 pid:14909 tgid:14908 ppid:13534  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5258 [inline]
 __schedule+0x150e/0x5070 kernel/sched/core.c:6866
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7193
 irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:trace_lock_release include/trace/events/lock.h:69 [inline]
RIP: 0010:lock_release+0x44/0x3b0 kernel/locking/lockdep.c:5879
Code: 8b 05 b0 11 01 11 48 89 44 24 28 0f 1f 44 00 00 65 8b 05 b3 11 01 11 83 f8 08 0f 83 87 02 00 00 89 c0 48 0f a3 05 dc 90 03 0e <73> 0d e8 f5 f8 08 00 84 c0 0f 84 a3 02 00 00 83 3d f6 c0 03 0e 00
RSP: 0018:ffffc90004136e50 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffffffff90347401 RCX: a554577122795e00
RDX: ffffc90004137001 RSI: ffffffff81742f85 RDI: ffffffff8e13f2e0
RBP: dffffc0000000000 R08: ffffc90004137070 R09: 0000000000000000
R10: ffffc90004137038 R11: fffff52000826e09 R12: ffffc90004137080
R13: ffffffff81742f85 R14: ffffffff8e13f2e0 R15: ffffffff81742f85
 rcu_lock_release include/linux/rcupdate.h:341 [inline]
 rcu_read_unlock include/linux/rcupdate.h:897 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1195 [inline]
 unwind_next_frame+0x1ab1/0x23d0 arch/x86/kernel/unwind_orc.c:695
 __unwind_start+0x5b9/0x760 arch/x86/kernel/unwind_orc.c:773
 unwind_start arch/x86/include/asm/unwind.h:64 [inline]
 arch_stack_walk+0xe4/0x150 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5267 [inline]
 kmem_cache_alloc_node_noprof+0x43c/0x720 mm/slub.c:5319
 kmalloc_reserve+0xbd/0x290 net/core/skbuff.c:586
 __alloc_skb+0x27e/0x430 net/core/skbuff.c:690
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6712
 sock_alloc_send_pskb+0x84d/0x980 net/core/sock.c:2995
 sock_alloc_send_skb include/net/sock.h:1885 [inline]
 j1939_sk_alloc_skb net/can/j1939/socket.c:889 [inline]
 j1939_sk_send_loop net/can/j1939/socket.c:1153 [inline]
 j1939_sk_sendmsg+0x6f5/0x1350 net/can/j1939/socket.c:1288
 sock_sendmsg_nosec+0x18f/0x1d0 net/socket.c:737
 __sock_sendmsg net/socket.c:752 [inline]
 ____sys_sendmsg+0x577/0x880 net/socket.c:2610
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2664
 __sys_sendmmsg+0x227/0x430 net/socket.c:2753
 __do_sys_sendmmsg net/socket.c:2780 [inline]
 __se_sys_sendmmsg net/socket.c:2777 [inline]
 __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2777
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1f4f58f749
RSP: 002b:00007f1f50459038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f1f4f7e5fa0 RCX: 00007f1f4f58f749
RDX: 03fffffffffffe3d RSI: 0000200000003e40 RDI: 0000000000000006
RBP: 00007f1f4f613f91 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000000f5 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1f4f7e6038 R14: 00007f1f4f7e5fa0 R15: 00007ffdcab83d58
 </TASK>
rcu: rcu_preempt kthread starved for 10543 jiffies! g75061 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:26208 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5258 [inline]
 __schedule+0x150e/0x5070 kernel/sched/core.c:6866
 __schedule_loop kernel/sched/core.c:6948 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6963
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 33 9e 2a 00 f3 0f 1e fa fb f4 <e9> 48 ee 02 00 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0000:ffffffff8de07d80 EFLAGS: 000002c6
RAX: 65813764d5b03c00 RBX: ffffffff819786ba RCX: 65813764d5b03c00
RDX: 0000000000000001 RSI: ffffffff8d997e54 RDI: ffffffff8be07960
RBP: ffffffff8de07ea8 R08: ffff8880b86336db R09: 1ffff110170c66db
R10: dffffc0000000000 R11: ffffed10170c66dc R12: ffffffff8fa22f70
R13: 1ffffffff1bd29b8 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125c25000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffe70 CR3: 000000002928c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x1ea/0x520 kernel/sched/idle.c:332
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:430
 rest_init+0x2de/0x300 init/main.c:758
 start_kernel+0x3ac/0x400 init/main.c:1208
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x147
 </TASK>