rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P13259/1:b..l P13359/1:b..l
	(detected by 0, t=10502 jiffies, g=83233, q=105 ncpus=2)
task:syz.7.1880      state:R  running task     stack:26224 pid:13359 ppid:10609  flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6731
 preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6755
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x10d/0x120 kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x128/0x190 kernel/sched/wait.c:208
 sock_def_readable+0x15b/0x280 net/core/sock.c:3316
 __netlink_sendskb net/netlink/af_netlink.c:1264 [inline]
 netlink_broadcast_deliver net/netlink/af_netlink.c:1399 [inline]
 do_one_broadcast net/netlink/af_netlink.c:1479 [inline]
 netlink_broadcast+0xcea/0x10d0 net/netlink/af_netlink.c:1519
 uevent_net_broadcast_untagged lib/kobject_uevent.c:331 [inline]
 kobject_uevent_net_broadcast+0x364/0x530 lib/kobject_uevent.c:409
 kobject_uevent_env+0x54c/0x8a0 lib/kobject_uevent.c:608
 loop_configure+0xec6/0x1230 drivers/block/loop.c:1109
 lo_ioctl+0x21c/0x1d10 drivers/block/loop.c:1546
 blkdev_ioctl+0x37b/0x740 block/ioctl.c:626
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f247f19ab4b
RSP: 002b:00007f247d3f5d00 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00007f247f19ab4b
RDX: 0000000000000005 RSI: 0000000000004c00 RDI: 0000000000000006
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005
R13: 00007f247d3f5ddc R14: 00007f247d3f5de0 R15: 00007f2474fd6000
 </TASK>
task:syz.0.1863      state:R  running task     stack:23600 pid:13259 ppid:8806   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_notrace+0xd9/0x120 kernel/sched/core.c:6824
 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
 rcu_is_watching+0x76/0xa0 kernel/rcu/tree.c:722
 rcu_read_unlock include/linux/rcupdate.h:820 [inline]
 mapping_get_entry mm/filemap.c:1899 [inline]
 __filemap_get_folio+0x340/0xdb0 mm/filemap.c:1943
 shmem_get_folio_gfp+0x310/0x3400 mm/shmem.c:1881
 shmem_get_folio mm/shmem.c:2072 [inline]
 shmem_write_begin+0xee/0x3f0 mm/shmem.c:2556
 generic_perform_write+0x2fa/0x5c0 mm/filemap.c:3862
 __generic_file_write_iter+0x148/0x2a0 mm/filemap.c:3960
 generic_file_write_iter+0xab/0x2e0 mm/filemap.c:3989
 __kernel_write_iter+0x285/0x650 fs/read_write.c:517
 dump_emit_page fs/coredump.c:950 [inline]
 dump_user_range+0x412/0x850 fs/coredump.c:977
 elf_core_dump+0x30a6/0x35d0 fs/binfmt_elf.c:2354
 do_coredump+0x165b/0x22f0 fs/coredump.c:824
 get_signal+0x10aa/0x1350 kernel/signal.c:2857
 arch_do_signal_or_restart+0xc4/0x1350 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:316
 exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1490
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7ff38019aec1
RSP: 002b:0000000000000030 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007ff380415fa0 RCX: 00007ff38019aeb9
RDX: 0000000000000000 RSI: 0000000000000030 RDI: 0000000000000600
RBP: 00007ff380208c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007ff380416038 R14: 00007ff380415fa0 R15: 00007ffef7e26738
 </TASK>
rcu: rcu_preempt kthread starved for 10581 jiffies! g83233 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:27504 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:rcu_gp_fqs_loop+0x306/0x1340 kernel/rcu/tree.c:1706
Code: 41 f6 c7 02 75 26 48 83 3d 2e 71 45 0b 00 75 0a 48 83 3d 9c 71 45 0b 00 74 12 48 85 db 74 0d 48 89 df e8 2d 79 c8 08 48 89 c3 <eb> ad 48 c7 c7 d8 30 b3 8c 48 8d b4 24 c0 00 00 00 e8 e4 bf f3 ff
RSP: 0018:ffffc90000157cc0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88813fec5940
RDX: 0000000000000000 RSI: ffffffffffffdb6a RDI: 0000000000000000
RBP: ffffc90000157e10 R08: ffffc90000157adf R09: ffffc90000157a60
R10: dffffc0000000000 R11: fffff5200002af5c R12: 0000000000000000
R13: ffffffff8cb33080 R14: ffffc90000157d88 R15: 0000000000000000
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 a7 10 9d f7 e9 44 ff ff ff e8 7d 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 87 5d 50 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffffff8c807d88 EFLAGS: 000002c6
RAX: 4361b8b0cd21a900 RBX: ffffffff8a3651a7 RCX: 4361b8b0cd21a900
RDX: 0000000000000001 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0c20
RBP: ffffffff8c807ec0 R08: ffff8880b8e3580b R09: 1ffff110171c6b01
R10: dffffc0000000000 R11: ffffed10171c6b02 R12: 1ffffffff1900fbc
R13: dffffc0000000000 R14: ffffffff8c8bc740 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000027000 CR3: 000000002402c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x20d/0x5a0 kernel/sched/idle.c:303
 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401
 rest_init+0x2dc/0x300 init/main.c:745
 arch_call_rest_init+0xa/0xa init/main.c:905
 start_kernel+0x493/0x53c init/main.c:1152
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>