rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P28411/2:b..l
rcu: (detected by 0, t=10502 jiffies, g=190721, q=412 ncpus=2)
task:kworker/u8:23 state:R running task stack:22168 pid:28411 tgid:28411 ppid:2 task_flags:0x4388060 flags:0x00080000
Workqueue: loop8 loop_rootcg_workfn
Call Trace:
context_switch kernel/sched/core.c:5258 [inline]
__schedule+0x150e/0x5070 kernel/sched/core.c:6866
preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7193
irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x16c/0x340 kernel/locking/lockdep.c:5872
Code: 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 44 41 01 11 <48> 3b 44 24 58 0f 85 e5 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc900042bef50 EFLAGS: 00000206
RAX: 321b563ce4653300 RBX: 0000000000000000 RCX: 321b563ce4653300
RDX: 000000002621dcd5 RSI: ffffffff8db7ed49 RDI: ffffffff8be07960
RBP: ffffffff81fa79ec R08: ffffffff81fa79ec R09: ffffffff8e13f2e0
R10: 0000000000000406 R11: 0000000000000000 R12: 0000000000000002
R13: ffffffff8e13f2e0 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
rcu_read_lock include/linux/rcupdate.h:867 [inline]
page_ref_add_unless include/linux/page_ref.h:235 [inline]
folio_ref_add_unless include/linux/page_ref.h:248 [inline]
folio_try_get+0x38/0x340 include/linux/page_ref.h:264
find_get_entry mm/filemap.c:2076 [inline]
find_lock_entries+0x24f/0xa60 mm/filemap.c:2166
shmem_undo_range+0x254/0x1490 mm/shmem.c:1119
shmem_truncate_range mm/shmem.c:1249 [inline]
shmem_fallocate+0x491/0xe70 mm/shmem.c:3727
lo_fallocate drivers/block/loop.c:261 [inline]
do_req_filebacked drivers/block/loop.c:432 [inline]
loop_handle_cmd drivers/block/loop.c:1926 [inline]
loop_process_work+0x8a7/0x10b0 drivers/block/loop.c:1961
process_one_work+0x93a/0x15a0 kernel/workqueue.c:3279
process_scheduled_works kernel/workqueue.c:3362 [inline]
worker_thread+0x9b0/0xee0 kernel/workqueue.c:3443
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
rcu: rcu_preempt kthread starved for 10537 jiffies! g190721 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:27104 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5258 [inline]
__schedule+0x150e/0x5070 kernel/sched/core.c:6866
__schedule_loop kernel/sched/core.c:6948 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6963
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+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 29809 Comm: syz.8.5432 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:raw_spin_rq_unlock_irq+0x13/0x90 kernel/sched/sched.h:1569
Code: cc e8 11 86 ca 09 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 41 57 41 56 53 eb 16 e8 b4 23 cd 09 e8 9f 68 36 00 fb 5b <41> 5e 41 5f c3 cc cc cc cc cc f3 0f 1e fa 49 be 00 00 00 00 00 fc
RSP: 0018:ffffc90004a374e8 EFLAGS: 00000282
RAX: 401acfc63aa51000 RBX: ffff8880b863ab00 RCX: 401acfc63aa51000
RDX: 0000000000000006 RSI: ffffffff8d997e54 RDI: ffffffff8be07960
RBP: ffffc90004a37718 R08: ffffffff8fa22f77 R09: 1ffffffff1f445ee
R10: dffffc0000000000 R11: fffffbfff1f445ef R12: dffffc0000000000
R13: ffff88802eba3d00 R14: dffffc0000000000 R15: ffff8880b863b958
FS: 0000000000000000(0000) GS:ffff888125c25000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd11ec024e2 CR3: 000000002fe1e000 CR4: 00000000003526f0
Call Trace:
__schedule+0x1a1b/0x5070 kernel/sched/core.c:6874
__schedule_loop kernel/sched/core.c:6948 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6963
xfs_extent_busy_wait_group fs/xfs/xfs_extent_busy.c:659 [inline]
xfs_extent_busy_wait_all+0x1e9/0x570 fs/xfs/xfs_extent_busy.c:672
xfs_unmount_flush_inodes+0x2a/0xd0 fs/xfs/xfs_mount.c:618
xfs_unmountfs+0x152/0x320 fs/xfs/xfs_mount.c:1322
xfs_fs_put_super+0x65/0x160 fs/xfs/xfs_super.c:1254
generic_shutdown_super+0x135/0x2c0 fs/super.c:643
kill_block_super+0x44/0x90 fs/super.c:1722
xfs_kill_sb+0x15/0x50 fs/xfs/xfs_super.c:2297
deactivate_locked_super+0xbc/0x130 fs/super.c:474
cleanup_mnt+0x425/0x4c0 fs/namespace.c:1318
task_work_run+0x1d4/0x260 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x8bd/0x25b0 kernel/exit.c:971
do_group_exit+0x21c/0x2d0 kernel/exit.c:1112
get_signal+0x1285/0x1340 kernel/signal.c:3034
arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
exit_to_user_mode_loop kernel/entry/common.c:75 [inline]
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
irqentry_exit+0x177/0x660 kernel/entry/common.c:196
exc_page_fault+0xab/0x100 arch/x86/mm/fault.c:1535
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7f213ef8f751
Code: Unable to access opcode bytes at 0x7f213ef8f727.
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f213f1e6090 RCX: 00007f213ef8f749
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007f213f013f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f213f1e6128 R14: 00007f213f1e6090 R15: 00007ffc591b5ec8