syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P13910/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=54265, q=724 ncpus=2)
task:syz.1.2075      state:R  running task     stack:26280 pid:13910 tgid:13910 ppid:8462   task_flags:0x40004c flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5396 [inline]
 __schedule+0x116a/0x5de0 kernel/sched/core.c:6785
 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:6965
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 zap_pte_range mm/memory.c:1765 [inline]
 zap_pmd_range mm/memory.c:1827 [inline]
 zap_pud_range mm/memory.c:1856 [inline]
 zap_p4d_range mm/memory.c:1877 [inline]
 unmap_page_range+0x109c/0x4380 mm/memory.c:1898
 unmap_single_vma.constprop.0+0x153/0x240 mm/memory.c:1941
 unmap_vmas+0x218/0x470 mm/memory.c:1985
 exit_mmap+0x1b9/0xb90 mm/mmap.c:1284
 __mmput+0x12a/0x410 kernel/fork.c:1121
 mmput+0x62/0x70 kernel/fork.c:1144
 exit_mm kernel/exit.c:581 [inline]
 do_exit+0x7bc/0x2bd0 kernel/exit.c:943
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1104
 __do_sys_exit_group kernel/exit.c:1115 [inline]
 __se_sys_exit_group kernel/exit.c:1113 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1113
 x64_sys_call+0x1530/0x1730 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f950f18e929
RSP: 002b:00007ffc3f5a86a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f950f18e929
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffc3f5a870c R08: 0000000f3f5a879f R09: 00000000000927c0
R10: 0000000000004ee4 R11: 0000000000000246 R12: 0000000000000116
R13: 00000000000927c0 R14: 00000000000b0364 R15: 00007ffc3f5a8760
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10493 jiffies! g54265 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=56133
rcu: rcu_preempt kthread starved for 10494 jiffies! g54265 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27704 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5396 [inline]
 __schedule+0x116a/0x5de0 kernel/sched/core.c:6785
 __schedule_loop kernel/sched/core.c:6863 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6878
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2054
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2256
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 13928 Comm: syz.2.2077 Not tainted 6.16.0-rc1-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:lock_release+0x24/0x2f0 kernel/locking/lockdep.c:5879
Code: 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 41 55 41 54 49 89 f4 53 48 89 fb 48 83 ec 18 65 48 8b 05 d9 48 34 12 48 89 44 24 10 <31> c0 0f 1f 44 00 00 65 8b 05 f2 48 34 12 83 f8 07 0f 87 38 02 00
RSP: 0018:ffffc90000a08de0 EFLAGS: 00000082
RAX: 5a72108509e12300 RBX: ffff8880b8527c98 RCX: ffffffff81a8e411
RDX: 1ffff1100675ec6d RSI: ffffffff81a8ea99 RDI: ffff8880b8527c98
RBP: 0000000000000046 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff81a8ea99
R13: 1854960725258044 R14: ffff888033af6340 R15: ffffffff899272e0
FS:  00007f85ebbdc6c0(0000) GS:ffff888124854000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f85ead746c0 CR3: 00000000326da000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:149 [inline]
 _raw_spin_unlock_irqrestore+0x1a/0x80 kernel/locking/spinlock.c:194
 __run_hrtimer kernel/time/hrtimer.c:1757 [inline]
 __hrtimer_run_queues+0x529/0xad0 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x108/0x3f0 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__sanitizer_cov_trace_pc+0x56/0x70 kernel/kcov.c:222
Code: 00 f0 00 75 35 8b 82 3c 16 00 00 85 c0 74 2b 8b 82 18 16 00 00 83 f8 02 75 20 48 8b 8a 20 16 00 00 8b 92 1c 16 00 00 48 8b 01 <48> 83 c0 01 48 39 d0 73 07 48 89 01 48 89 34 c1 e9 c5 85 c6 09 0f
RSP: 0018:ffffc90004bdf7e0 EFLAGS: 00000246
RAX: 000000000005a5af RBX: 000000000000000a RCX: ffffc9000d0b9000
RDX: 0000000000080000 RSI: ffffffff8a248895 RDI: 0000000000000004
RBP: 1ffff9200097befd R08: 0000000000000004 R09: 000000000000000b
R10: 000000000000000a R11: 0000000000000001 R12: 7fffffffffffffff
R13: ffff88802604b880 R14: 000000000000000b R15: ffff88802604b828
 spin_unlock include/linux/spinlock.h:391 [inline]
 unix_wait_for_peer+0x235/0x280 net/unix/af_unix.c:1582
 unix_dgram_sendmsg+0x16bf/0x1840 net/unix/af_unix.c:2187
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 ____sys_sendmsg+0xa98/0xc70 net/socket.c:2566
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620
 __sys_sendmmsg+0x200/0x420 net/socket.c:2709
 __do_sys_sendmmsg net/socket.c:2736 [inline]
 __se_sys_sendmmsg net/socket.c:2733 [inline]
 __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2733
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f85ead8e929
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:00007f85ebbdc038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f85eafb5fa0 RCX: 00007f85ead8e929
RDX: 0000000000000651 RSI: 0000200000000000 RDI: 0000000000000005
RBP: 00007f85eae10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f85eafb5fa0 R15: 00007ffe7b372bf8
 </TASK>