syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P16731/1:b..l P16722/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=92545, q=403 ncpus=2)
task:syz.3.2528      state:R  running task     stack:25608 pid:16722 tgid:16721 ppid:15821  task_flags:0x400040 flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7256
 irqentry_exit+0x6f/0x90 kernel/entry/common.c:211
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_is_held_type+0x137/0x190 kernel/locking/lockdep.c:5945
Code: 01 75 44 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 4c 41 f7 c4 00 02 00 00 74 01 fb 65 48 8b 05 09 0a 28 07 <48> 3b 44 24 08 75 43 89 d8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc900001f7260 EFLAGS: 00000206
RAX: 7a24657815cac000 RBX: 0000000000000001 RCX: 7a24657815cac000
RDX: ffffc90022c07000 RSI: ffffffff8d8f29f0 RDI: ffffffff8bbf05e0
RBP: 00000000ffffffff R08: 0000000000000000 R09: ffffffff822f1dfa
R10: ffff88802a1fe3c0 R11: ffffffff81ac2d30 R12: 0000000000000246
R13: ffff88802a1fdac0 R14: ffffffff8df3d2e0 R15: 0000000000000002
 lookup_page_ext mm/page_ext.c:254 [inline]
 page_ext_lookup+0xe7/0x180 mm/page_ext.c:509
 page_ext_iter_begin include/linux/page_ext.h:132 [inline]
 __update_page_owner_handle+0x12f/0x570 mm/page_owner.c:247
 __set_page_owner+0x10b/0x4c0 mm/page_owner.c:333
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2435
 shmem_alloc_folio mm/shmem.c:1871 [inline]
 shmem_alloc_and_add_folio+0x447/0xf60 mm/shmem.c:1910
 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2533
 shmem_get_folio mm/shmem.c:2639 [inline]
 shmem_write_begin+0xf7/0x2b0 mm/shmem.c:3289
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4242
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3464
 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/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f23ef38da7f
RSP: 002b:00007f23f0146df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007f23ef38da7f
RDX: 0000000001000000 RSI: 00007f23e5000000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000005597
R10: 0000000000000002 R11: 0000000000000293 R12: 0000000000000003
R13: 00007f23f0146ef0 R14: 00007f23f0146eb0 R15: 00007f23e5000000
 </TASK>
task:syz.8.2527      state:R  running task     stack:26888 pid:16731 tgid:16717 ppid:13419  task_flags:0x40054c flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7113
 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7137
 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+0x3f/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 zap_pte_range mm/memory.c:1884 [inline]
 zap_pmd_range mm/memory.c:1946 [inline]
 zap_pud_range mm/memory.c:1975 [inline]
 zap_p4d_range mm/memory.c:1996 [inline]
 unmap_page_range+0x3a7f/0x4370 mm/memory.c:2017
 unmap_single_vma mm/memory.c:2060 [inline]
 unmap_vmas+0x399/0x580 mm/memory.c:2104
 exit_mmap+0x240/0xb40 mm/mmap.c:1280
 __mmput+0x118/0x430 kernel/fork.c:1133
 exit_mm+0x1da/0x2c0 kernel/exit.c:582
 do_exit+0x648/0x2300 kernel/exit.c:954
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1107
 get_signal+0x1285/0x1340 kernel/signal.c:3034
 arch_do_signal_or_restart+0xa0/0x790 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x72/0x130 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff096f8efc9
RSP: 002b:00007ff097e770e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007ff0971e6098 RCX: 00007ff096f8efc9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007ff0971e6098
RBP: 00007ff0971e6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff0971e6128 R14: 00007ffd35bb18a0 R15: 00007ffd35bb1988
 </TASK>
rcu: rcu_preempt kthread starved for 10438 jiffies! g92545 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:26784 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 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+0x4bc/0x870 arch/x86/kernel/process.c:158
 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 16734 Comm: syz.9.2533 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:216
Code: 8b 3d a4 c1 d2 0b 48 89 de 5b e9 93 86 5a 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0c 25 08 20 6e 92 65 8b 15 a8 1b ae 10 81 e2 00 01 ff 00
RSP: 0018:ffffc9000c1a7d78 EFLAGS: 00000246
RAX: ffffffff81655dd7 RBX: ffffc9000c1a7f48 RCX: ffff88802a7a8000
RDX: 0000000000000002 RSI: 00000000ffffffff RDI: 00000000ffffffff
RBP: ffffc9000c1a7eb0 R08: ffffffff8f7cd477 R09: 1ffffffff1ef9a8e
R10: dffffc0000000000 R11: fffffbfff1ef9a8f R12: 00000000ffffffff
R13: dffffc0000000000 R14: ffff88802a7a8000 R15: ffffffffffffffff
FS:  00007f5bc25446c0(0000) GS:ffff88812613e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd3ef9279a6 CR3: 000000005e891000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 handle_signal arch/x86/kernel/signal.c:264 [inline]
 arch_do_signal_or_restart+0xf7/0x790 arch/x86/kernel/signal.c:339
 exit_to_user_mode_loop+0x72/0x130 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5bc178efc7
Code: ff ff 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
RSP: 002b:00007f5bc25440e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f5bc19e5fa8 RCX: 00007f5bc178efc9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f5bc19e5fa8
RBP: 00007f5bc19e5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5bc19e6038 R14: 00007fff878796d0 R15: 00007fff878797b8
 </TASK>
vkms_vblank_simulate: vblank timer overrun