syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P25104/1:b..l P28178/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=203761, q=580 ncpus=2)
task:syz-executor    state:R  running task     stack:22216 pid:28178 tgid:28178 ppid:28167  task_flags:0x400140 flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1821/0x5740 kernel/sched/core.c:7189
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
 irqentry_exit+0x14f/0x760 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:unwind_next_frame+0x19f0/0x2550 arch/x86/kernel/unwind_orc.c:693
Code: 49 8d 56 40 4c 89 f7 4c 89 e6 e8 1b 0e 00 00 84 c0 0f 84 46 01 00 00 48 bd 00 00 00 00 00 fc ff df 48 8b 44 24 20 0f b6 04 28 <84> c0 0f 85 6a 08 00 00 b3 01 8b 84 24 8c 00 00 00 41 39 06 4c 8b
RSP: 0018:ffffc9000561f118 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffffffff90d3be2e RCX: 0000000000000001
RDX: ffffc9000561f228 RSI: dffffc0000000000 RDI: ffffc9000561f448
RBP: dffffc0000000000 R08: ffffc9000561f448 R09: ffffc9000561f238
R10: dffffc0000000000 R11: fffff52000ac3e49 R12: ffffc9000561f448
R13: 1ffff92000ac3e3f R14: ffffc9000561f1e8 R15: 1ffffffff21a77c6
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x122/0x230 mm/page_owner.c:165
 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 free_unref_folios+0xcec/0x1480 mm/page_alloc.c:3004
 folios_put_refs+0x9ff/0xb40 mm/swap.c:1008
 folio_batch_release include/linux/folio_batch.h:101 [inline]
 shmem_undo_range+0x52c/0x1660 mm/shmem.c:1149
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x289/0xae0 mm/shmem.c:1407
 evict+0x61e/0xb10 fs/inode.c:841
 __dentry_kill+0x1a2/0x690 fs/dcache.c:718
 finish_dput+0xc9/0x480 fs/dcache.c:927
 __fput+0x691/0xa60 fs/file_table.c:518
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xf3/0x4d0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f91bdd5d68e
RSP: 002b:00007fff641bc348 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 000055556c51b500 RCX: 00007f91bdd5d68e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fff641bc3ec R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000035
R13: 00000000000927c0 R14: 00000000001861a8 R15: 00007fff641bc440
 </TASK>
task:syz-executor    state:R  running task     stack:22360 pid:25104 tgid:25104 ppid:25089  task_flags:0x400140 flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1821/0x5740 kernel/sched/core.c:7189
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
 irqentry_exit+0x14f/0x760 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__nr_to_section include/linux/mmzone.h:2061 [inline]
RIP: 0010:__pfn_to_section include/linux/mmzone.h:2198 [inline]
RIP: 0010:lookup_page_ext mm/page_ext.c:255 [inline]
RIP: 0010:page_ext_lookup+0x50/0x180 mm/page_ext.c:513
Code: ee 16 e9 2d 01 00 00 e8 9e 40 89 ff 41 bf 00 00 04 00 49 bd 00 00 00 00 00 fc ff df 4c 89 f7 4c 89 fe e8 e3 42 89 ff 4d 39 fe <0f> 83 ef 00 00 00 48 c7 c0 00 ba 4a 9a 48 c1 e8 03 42 80 3c 28 00
RSP: 0018:ffffc90009bbf348 EFLAGS: 00000287
RAX: ffffffff823c814d RBX: 00000000000a7513 RCX: ffff88804ea1bd80
RDX: 0000000000000000 RSI: 0000000000001000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff823ac26e R09: ffffffff8e95cd60
R10: 000000000000000f R11: ffffffff81b0ebd0 R12: 00000000000a7513
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000001000
 page_ext_iter_begin include/linux/page_ext.h:133 [inline]
 __update_page_owner_free_handle+0x103/0x470 mm/page_owner.c:284
 __reset_page_owner+0x85/0x1f0 mm/page_owner.c:321
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 free_unref_folios+0xcec/0x1480 mm/page_alloc.c:3004
 folios_put_refs+0x9ff/0xb40 mm/swap.c:1008
 folio_batch_release include/linux/folio_batch.h:101 [inline]
 truncate_inode_pages_range+0x3dd/0xe30 mm/truncate.c:408
 ext4_evict_inode+0x2d9/0x10e0 fs/ext4/inode.c:197
 evict+0x61e/0xb10 fs/inode.c:841
 dispose_list fs/inode.c:883 [inline]
 evict_inodes+0x75a/0x7f0 fs/inode.c:937
 generic_shutdown_super+0xaa/0x2d0 fs/super.c:632
 kill_block_super+0x44/0x90 fs/super.c:1725
 ext4_kill_sb+0x68/0xb0 fs/ext4/super.c:7492
 deactivate_locked_super+0xbc/0x130 fs/super.c:476
 cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xf3/0x4d0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1fc999e097
RSP: 002b:00007ffcfafecef8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f1fc9a321ca RCX: 00007f1fc999e097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffcfafecfb0
RBP: 00007ffcfafecfb0 R08: 00007ffcfafedfb0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcfafee040
R13: 00007f1fc9a321ca R14: 0000000000186e02 R15: 00007ffcfafee080
 </TASK>
rcu: rcu_preempt kthread starved for 10598 jiffies! g203761 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:27592 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1821/0x5740 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7283
 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
Code: 9b 7d 02 e9 fe 7f 67 f5 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 53 a1 20 00 fb f4 <e9> d7 7f 67 f5 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc90000197e20 EFLAGS: 00000242
RAX: 0000000002a0c245 RBX: ffffffff819a93ba RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8dfa6837 RDI: ffffffff8c28af60
RBP: ffffc90000197f10 R08: ffff8880b87339db R09: 1ffff110170e673b
R10: dffffc0000000000 R11: ffffed10170e673c R12: 0000000000000001
R13: 1ffff11003b54000 R14: 0000000000000001 R15: 1ffff11003b54000
FS:  0000000000000000(0000) GS:ffff88812538d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3041bff8 CR3: 0000000096247000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/kernel/process.c:766 [inline]
 default_idle+0x9/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x36a/0x5f0 kernel/sched/idle.c:352
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:451
 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
 common_startup_64+0x13e/0x147
 </TASK>