syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P12861/1:b..l
	(detected by 1, t=10503 jiffies, g=72557, q=103 ncpus=2)
task:syz.5.1757      state:R  running task     stack:26496 pid:12861 ppid:11631  flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:debug_lockdep_rcu_enabled+0x25/0x30 kernel/rcu/update.c:281
Code: 00 00 cc cc 00 31 c0 83 3d b7 29 08 04 00 74 1d 83 3d 42 5d 08 04 00 74 14 65 48 8b 0d 94 26 eb 75 31 c0 83 b9 dc 0a 00 00 00 <0f> 94 c0 c3 00 00 cc cc 00 00 cc 48 8b 3c 24 e8 47 fb ff ff 66 90
RSP: 0018:ffffc90003e87348 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff88801a9af118 RCX: ffff88804e4a5940
RDX: ffffc9000e78c000 RSI: 0000000000018fcf RDI: 0000000000018fd0
RBP: 0000000000140cca R08: dffffc0000000000 R09: ffffed1003535e24
R10: ffffed1003535e24 R11: 1ffff11003535e23 R12: 0000000000000001
R13: 0000000000000000 R14: ffffea000117f2c0 R15: 0000000000000001
 rcu_read_unlock include/linux/rcupdate.h:820 [inline]
 page_ext_put+0x17/0xb0 mm/page_ext.c:182
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 __folio_alloc+0xe/0x30 mm/page_alloc.c:5646
 vma_alloc_folio+0x4a3/0x900 mm/mempolicy.c:2243
 shmem_alloc_folio mm/shmem.c:1589 [inline]
 shmem_alloc_and_acct_folio+0x42e/0xb60 mm/shmem.c:1613
 shmem_get_folio_gfp+0x1361/0x3400 mm/shmem.c:1941
 shmem_get_folio mm/shmem.c:2072 [inline]
 shmem_write_begin+0xee/0x3f0 mm/shmem.c:2556
 generic_perform_write+0x2db/0x560 mm/filemap.c:3846
 __generic_file_write_iter+0x172/0x430 mm/filemap.c:3974
 generic_file_write_iter+0xab/0x2e0 mm/filemap.c:4006
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x44c/0x960 fs/read_write.c:584
 ksys_write+0x143/0x240 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3bcdb8d69f
RSP: 002b:00007f3bcbdd4df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000100000 RCX: 00007f3bcdb8d69f
RDX: 0000000000100000 RSI: 00007f3bc3994000 RDI: 000000000000000c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000c1e
R10: 0000000000000fd0 R11: 0000000000000293 R12: 000000000000000c
R13: 00007f3bcbdd4ef0 R14: 00007f3bcbdd4eb0 R15: 00007f3bc3994000
 </TASK>
rcu: rcu_preempt kthread starved for 10548 jiffies! g72557 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:26912 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 12856 Comm: syz.6.1756 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:__send_signal_locked+0xd7/0xde0 kernel/signal.c:-1
Code: e8 9e 81 30 00 40 0f b6 d5 44 89 ff 4c 89 ee e8 7f 4f 00 00 84 c0 74 4d 31 ff 44 89 e6 e8 e1 84 30 00 45 85 e4 48 89 5c 24 18 <44> 89 64 24 14 74 46 e8 6d 81 30 00 4d 8d b5 10 09 00 00 4c 89 f0
RSP: 0018:ffffc90000007e08 EFLAGS: 00000002
RAX: ffffffff81504e9f RBX: 0000000000000001 RCX: 0000000000010000
RDX: ffff88804e4a3b80 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000002
R10: 0000000000000001 R11: 0000000000010000 R12: 0000000000000001
R13: ffff88804e4a3b80 R14: 0000000000000001 R15: 0000000000000011
FS:  00007f98d91296c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa5ff653000 CR3: 0000000056055000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 do_send_sig_info kernel/signal.c:1301 [inline]
 group_send_sig_info+0x1f6/0x250 kernel/signal.c:1449
 do_bpf_send_signal+0x7b/0x150 kernel/trace/bpf_trace.c:840
 irq_work_single+0xd1/0x230 kernel/irq_work.c:211
 irq_work_run_list kernel/irq_work.c:242 [inline]
 irq_work_run+0x152/0x2e0 kernel/irq_work.c:251
 __sysvec_irq_work+0xba/0x350 arch/x86/kernel/irq_work.c:22
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x98/0xc0 arch/x86/kernel/irq_work.c:17
 </IRQ>
 <TASK>
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:207 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:147 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:254 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:206
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 89 f6 31 d2 e9 9f bd f7 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc900038f7cb0 EFLAGS: 00000246
RAX: 00000000000000f6 RBX: ffffffff8c5e3b88 RCX: 000000000000083f
RDX: 0000000000000000 RSI: 00000000000000f6 RDI: 000000000000083f
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffff5200071ef85
R10: fffff5200071ef85 R11: 1ffff9200071ef84 R12: ffff8880b8e33e01
R13: dffffc0000000000 R14: dffffc0000000000 R15: 0000000000000020
 arch_irq_work_raise+0x82/0xd0 arch/x86/kernel/irq_work.c:31
 irq_work_queue+0x95/0x140 kernel/irq_work.c:114
 bpf_send_signal_common+0x2b2/0x420 kernel/trace/bpf_trace.c:879
 ____bpf_send_signal kernel/trace/bpf_trace.c:888 [inline]
 bpf_send_signal+0x15/0x20 kernel/trace/bpf_trace.c:886
 bpf_prog_7ba5217f62dcd359+0x38/0x3c
 bpf_dispatcher_nop_func include/linux/bpf.h:1001 [inline]
 __bpf_prog_run include/linux/filter.h:603 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
 bpf_trace_run2+0x1cd/0x3b0 kernel/trace/bpf_trace.c:2324
 __bpf_trace_sys_enter+0x60/0x70 include/trace/events/syscalls.h:18
 trace_sys_enter+0x6b/0x80 include/trace/events/syscalls.h:18
 syscall_trace_enter+0xf0/0x150 kernel/entry/common.c:81
 do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:77
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f98d832adb9
Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 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 04 25
RSP: 002b:00007f98d9128b40 EFLAGS: 00000246 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f98d85c6098 RCX: 00007f98d832adb9
RDX: 00007f98d9128b40 RSI: 00007f98d9128c70 RDI: 0000000000000011
RBP: 00007f98d85c6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f98d85c6128 R14: 00007ffd976fe4a0 R15: 00007ffd976fe588
 </TASK>