rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9929/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=41669, q=238 ncpus=2)
task:syz.1.1118      state:R  running task     stack:25336 pid:9929  tgid:9928  ppid:5829   task_flags:0x400040 flags:0x00080000
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:debug_lockdep_rcu_enabled+0xd/0x40 kernel/rcu/update.c:320
Code: 8d 67 48 0f b9 3a 90 eb ca cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 31 c0 83 3d 17 78 44 04 00 <74> 1e 83 3d 2a a7 44 04 00 74 15 65 48 8b 0c 25 08 b0 9f 92 31 c0
RSP: 0018:ffffc90003e6f6e8 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffffffff8478821d RCX: 0000000000080000
RDX: ffffc9000c282000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: 0000000000000000 R08: ffffffff99c953c7 R09: 1ffffffff3392a78
R10: dffffc0000000000 R11: fffffbfff3392a79 R12: dffffc0000000000
R13: 0000000000000aed R14: 0000000000000000 R15: ffffffff99c953c4
 rcu_read_unlock include/linux/rcupdate.h:895 [inline]
 blk_cgroup_congested+0x167/0x210 block/blk-cgroup.c:2245
 __folio_throttle_swaprate+0x3c/0x140 mm/swapfile.c:4034
 folio_throttle_swaprate include/linux/swap.h:608 [inline]
 shmem_add_to_page_cache+0x6f1/0xba0 mm/shmem.c:899
 shmem_alloc_and_add_folio+0x829/0xf40 mm/shmem.c:1970
 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2568
 shmem_get_folio mm/shmem.c:2674 [inline]
 shmem_write_begin+0x16c/0x330 mm/shmem.c:3327
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4314
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3502
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5c9/0xb30 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 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: 0033:0x7f76ba58e1ff
RSP: 002b:00007f76bb494df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007f76ba58e1ff
RDX: 0000000001000000 RSI: 00007f76b0200000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000004451
R10: 0000200000008902 R11: 0000000000000293 R12: 0000000000000003
R13: 00007f76bb494ef0 R14: 00007f76bb494eb0 R15: 00007f76b0200000
 </TASK>
rcu: rcu_preempt kthread starved for 10423 jiffies! g41669 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:26840 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:
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: ee1acda6ed485a00 RBX: ffffffff819786ba RCX: ee1acda6ed485a00
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: 000000007d00a000 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>