syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P19824/1:b..l P4376/1:b..l P19718/1:b..l P3639/1:b..l P17794/1:b..l
	(detected by 1, t=10504 jiffies, g=160929, q=145 ncpus=2)
task:syz-executor    state:R  running task     stack:22096 pid:17794 ppid:17774  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:lock_acquire+0xfb/0x4a0 kernel/locking/lockdep.c:5635
Code: 45 6f 00 4c 0f a3 25 fc b6 bb 0c 73 0d e8 9d 32 08 00 84 c0 0f 84 2e 02 00 00 48 c7 c0 e4 28 20 8e 48 c1 e8 03 42 0f b6 04 38 <84> c0 0f 85 1d 02 00 00 83 3d 8a eb bb 0c 00 0f 84 0c 01 00 00 65
RSP: 0018:ffffc90004a57540 EFLAGS: 00000a03
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 197c7e681d9fd600
RDX: 0000000000000000 RSI: ffffffff8adf1380 RDI: ffffffff8adf1340
RBP: ffffc90004a57650 R08: ffffffff8e1ff42f R09: 1ffffffff1c3fe85
R10: dffffc0000000000 R11: fffffbfff1c3fe86 R12: 0000000000000001
R13: 1ffff9200094aeb4 R14: 0000000000000000 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 page_ext_get+0x3a/0x2a0 mm/page_ext.c:157
 __page_table_check_zero+0x134/0x4b0 mm/page_table_check.c:146
 page_table_check_free include/linux/page_table_check.h:46 [inline]
 free_pages_prepare mm/page_alloc.c:1487 [inline]
 free_pcp_prepare mm/page_alloc.c:1536 [inline]
 free_unref_page_prepare+0x8c4/0x9a0 mm/page_alloc.c:3413
 free_unref_page_list+0xbb/0x8e0 mm/page_alloc.c:3554
 release_pages+0x1fa6/0x2220 mm/swap.c:1035
 __pagevec_release+0x6d/0xe0 mm/swap.c:1055
 pagevec_release include/linux/pagevec.h:71 [inline]
 folio_batch_release include/linux/pagevec.h:135 [inline]
 shmem_undo_range+0x7c2/0x20c0 mm/shmem.c:946
 shmem_truncate_range mm/shmem.c:1062 [inline]
 shmem_evict_inode+0x25b/0xa80 mm/shmem.c:1171
 evict+0x4c9/0x8d0 fs/inode.c:705
 do_unlinkat+0x388/0x580 fs/namei.c:4405
 __do_sys_unlink fs/namei.c:4446 [inline]
 __se_sys_unlink fs/namei.c:4444 [inline]
 __x64_sys_unlink+0x45/0x50 fs/namei.c:4444
 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: 0033:0x7f39b359b907
RSP: 002b:00007ffc97545cf8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f39b359b907
RDX: 00007ffc97545d20 RSI: 00007ffc97545db0 RDI: 00007ffc97545db0
RBP: 00007ffc97545db0 R08: 00007ffc97546db0 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffc97546e40
R13: 00007f39b3632048 R14: 00000000001b71be R15: 00007ffc97546e80
 </TASK>
task:udevd           state:R  running task     stack:22512 pid:3639  ppid:1      flags:0x00004002
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_sendskb+0x97/0x130 net/netlink/af_netlink.c:1270
 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1872
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5be/0x970 net/socket.c:2518
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2572
 __sys_sendmsg net/socket.c:2601 [inline]
 __do_sys_sendmsg net/socket.c:2610 [inline]
 __se_sys_sendmsg+0x1bb/0x2a0 net/socket.c:2608
 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: 0033:0x7fe0680a7407
RSP: 002b:00007ffddce30340 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe06875d880 RCX: 00007fe0680a7407
RDX: 0000000000000000 RSI: 00007ffddce303a0 RDI: 0000000000000004
RBP: 000055cfc1d41100 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00000000000000b5
R13: 000055cfc1d1a9e0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
task:syz.0.4318      state:R  running task     stack:23696 pid:19718 ppid:14267  flags:0x00004002
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:check_kcov_mode kernel/kcov.c:193 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:245 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x32/0x80 kernel/kcov.c:320
Code: 04 f6 7f 7e 65 8b 15 05 f6 7f 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 57 83 b9 1c 16 00 00 00 74 4e 8b 91 f8 15 00 00 <83> fa 03 75 43 48 8b 91 00 16 00 00 44 8b 89 fc 15 00 00 49 c1 e1
RSP: 0018:ffffc90003db71d8 EFLAGS: 00000246
RAX: ffffffff81ac6cfa RBX: 0000000000002997 RCX: ffff88801b385940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003db7310 R08: ffffea00011e4ac7 R09: 1ffffd400023c958
R10: dffffc0000000000 R11: fffff9400023c959 R12: 1ffffd400023c95e
R13: ffffea00011e4af4 R14: 00fff6000008001e R15: ffffea00011e4ac0
 constant_test_bit arch/x86/include/asm/bitops.h:207 [inline]
 arch_test_bit arch/x86/include/asm/bitops.h:239 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
 folio_test_head include/linux/page-flags.h:788 [inline]
 folio_test_large include/linux/page-flags.h:809 [inline]
 folio_nr_pages include/linux/mm.h:1709 [inline]
 find_lock_entries+0x44a/0xbb0 mm/filemap.c:2127
 shmem_undo_range+0x288/0x20c0 mm/shmem.c:925
 shmem_truncate_range mm/shmem.c:1062 [inline]
 shmem_evict_inode+0x25b/0xa80 mm/shmem.c:1171
 evict+0x4c9/0x8d0 fs/inode.c:705
 __dentry_kill+0x431/0x650 fs/dcache.c:611
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xfa/0x1d0 fs/dcache.c:918
 __fput+0x5e0/0x920 fs/file_table.c:328
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x982/0x2480 kernel/exit.c:880
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 get_signal+0x1272/0x1350 kernel/signal.c:2871
 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:1485
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f887b19c821
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f887b415fa0 RCX: 00007f887b19c819
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007f887b232c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f887b416038 R14: 00007f887b415fa0 R15: 00007fff43f575a8
 </TASK>
task:kworker/u4:8    state:R  running task     stack:20432 pid:4376  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
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:lock_acquire+0x225/0x4a0 kernel/locking/lockdep.c:5666
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc900045f7ac0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 65264f1bfb85ea00
RDX: 0000000000000000 RSI: ffffffff8a8c22a0 RDI: ffffffff8adf13a0
RBP: ffffc900045f7bc8 R08: dffffc0000000000 R09: 1ffffffff215f248
R10: dffffc0000000000 R11: fffffbfff215f249 R12: 0000000000000001
R13: 1ffff920008bef64 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 batadv_nc_worker+0xeb/0x600 net/batman-adv/network-coding.c:719
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
task:syz.7.4254      state:R  running task     stack:23792 pid:19824 ppid:19461  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_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x225/0x4a0 kernel/locking/lockdep.c:5666
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc900047eeca0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 2ae311aafd640f00
RDX: 0000000000000000 RSI: ffffffff8a8c22a0 RDI: ffffffff8adf13a0
RBP: ffffc900047eeda8 R08: dffffc0000000000 R09: 1ffffffff215f248
R10: dffffc0000000000 R11: fffffbfff215f249 R12: 0000000000000001
R13: 1ffff920008fdda0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 mapping_get_entry mm/filemap.c:1878 [inline]
 __filemap_get_folio+0x130/0xdb0 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:1485
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7fbfd2f9c821
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007fbfd3216090 RCX: 00007fbfd2f9c819
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007fbfd3032c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007fbfd3216128 R14: 00007fbfd3216090 R15: 00007ffe1f8ed248
 </TASK>
rcu: rcu_preempt kthread starved for 10543 jiffies! g160929 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:25712 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
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 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: 1 PID: 19888 Comm: syz.5.4356 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 0e b0 2c f7 48 89 df e8 56 78 2d f7 e8 21 cf 50 f7 fb bf 01 00 00 00 <e8> a6 dc 20 f7 65 8b 05 f7 5f ca 75 85 c0 74 02 5b c3 e8 44 74 c8
RSP: 0018:ffffc90004bf7b98 EFLAGS: 00000282
RAX: 18683c27b8520800 RBX: ffff88802e871280 RCX: 18683c27b8520800
RDX: dffffc0000000000 RSI: ffffffff8a8c1120 RDI: 0000000000000001
RBP: ffff88802e871718 R08: ffff88802e871283 R09: 1ffff11005d0e250
R10: dffffc0000000000 R11: ffffed1005d0e251 R12: 1ffff11005d0e2e3
R13: 0000000000000021 R14: dffffc0000000000 R15: 0000000000000000
FS:  00007f40db3f36c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f40da5e9f00 CR3: 00000000489d8000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 get_signal+0x1163/0x1350 kernel/signal.c:2874
 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
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f40da59c817
Code: 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89
RSP: 002b:00007f40db3f3028 EFLAGS: 00000246
RAX: 0000000000000067 RBX: 00007f40da816360 RCX: 00007f40da59c819
RDX: 0000000000000025 RSI: 0000200000001a00 RDI: 0000000000000002
RBP: 00007f40da632c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f40da8163f8 R14: 00007f40da816360 R15: 00007ffd76c6cec8
 </TASK>