syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4227/1:b..l
	(detected by 1, t=10502 jiffies, g=31309, q=100)
task:kworker/u4:5    state:R  running task     stack:21536 pid: 4227 ppid:     2 flags:0x00004000
Workqueue: xfs_iwalk-8331 xfs_pwork_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6549
 preempt_schedule+0xd9/0xe0 kernel/sched/core.c:6574
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock_irq+0x3c/0x40 kernel/locking/spinlock.c:202
 spin_unlock_irq include/linux/spinlock.h:413 [inline]
 loop_queue_work drivers/block/loop.c:1068 [inline]
 loop_queue_rq+0x9f7/0xae0 drivers/block/loop.c:2201
 __blk_mq_issue_directly block/blk-mq.c:2008 [inline]
 __blk_mq_try_issue_directly+0x541/0x8b0 block/blk-mq.c:2064
 blk_mq_request_issue_directly block/blk-mq.c:2112 [inline]
 blk_mq_try_issue_list_directly+0x245/0x650 block/blk-mq.c:2130
 blk_mq_sched_insert_requests+0x284/0x570 block/blk-mq-sched.c:512
 blk_mq_flush_plug_list+0x5de/0x6b0 block/blk-mq.c:1965
 blk_flush_plug_list+0x44b/0x490 block/blk-core.c:1734
 blk_finish_plug+0x59/0x80 block/blk-core.c:1751
 _xfs_buf_ioapply+0x45d/0x6c0 fs/xfs/xfs_buf.c:1560
 __xfs_buf_submit+0x300/0x770 fs/xfs/xfs_buf.c:1623
 xfs_buf_submit fs/xfs/xfs_buf.c:58 [inline]
 _xfs_buf_read fs/xfs/xfs_buf.c:722 [inline]
 xfs_buf_read_map+0x41a/0xa00 fs/xfs/xfs_buf.c:786
 xfs_trans_read_buf_map+0x25c/0xa60 fs/xfs/xfs_trans_buf.c:289
 xfs_trans_read_buf fs/xfs/xfs_trans.h:210 [inline]
 xfs_read_agf+0x263/0x510 fs/xfs/libxfs/xfs_alloc.c:3011
 xfs_alloc_read_agf+0xce/0xbc0 fs/xfs/libxfs/xfs_alloc.c:3044
 xfs_alloc_fix_freelist+0x619/0x1a90 fs/xfs/libxfs/xfs_alloc.c:2570
 xfs_alloc_vextent+0xa3e/0x1b00 fs/xfs/libxfs/xfs_alloc.c:3203
 xfs_bmap_btalloc+0x1477/0x2bf0 fs/xfs/libxfs/xfs_bmap.c:3718
 xfs_bmapi_allocate+0x4f4/0xe30
 xfs_bmapi_write+0x99e/0x1880 fs/xfs/libxfs/xfs_bmap.c:4484
 xfs_dquot_disk_alloc+0x46f/0xb80 fs/xfs/xfs_dquot.c:325
 xfs_qm_dqread_alloc fs/xfs/xfs_dquot.c:647 [inline]
 xfs_qm_dqread+0x244/0x770 fs/xfs/xfs_dquot.c:692
 xfs_qm_dqget+0x26f/0x4e0 fs/xfs/xfs_dquot.c:897
 xfs_qm_quotacheck_dqadjust+0xe6/0x560 fs/xfs/xfs_qm.c:1085
 xfs_qm_dqusage_adjust+0x503/0x670 fs/xfs/xfs_qm.c:1197
 xfs_iwalk_ag_recs+0x4c1/0x810 fs/xfs/xfs_iwalk.c:220
 xfs_iwalk_run_callbacks+0x211/0x420 fs/xfs/xfs_iwalk.c:376
 xfs_iwalk_ag+0xad2/0xbd0 fs/xfs/xfs_iwalk.c:482
 xfs_iwalk_ag_work+0xf7/0x1a0 fs/xfs/xfs_iwalk.c:624
 xfs_pwork_work+0x78/0x180 fs/xfs/xfs_pwork.c:47
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 10558 jiffies! g31309 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:27064 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 schedule+0x11b/0x1f0 kernel/sched/core.c:6456
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </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: 8361 Comm: syz.6.591 Not tainted 5.15.169-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:lockdep_softirqs_on+0x1/0x590 kernel/locking/lockdep.c:4393
Code: 07 80 c1 03 38 c1 0f 8c 21 fe ff ff 48 c7 c7 48 99 e9 8d e8 41 b1 67 00 e9 10 fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 66 90 55 <48> 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec 80 00 00
RSP: 0018:ffffc90002fe7910 EFLAGS: 00000046
RAX: 0000000000000200 RBX: 1ffff920005fcf28 RCX: 0000000000040000
RDX: ffffc9000cbfa000 RSI: 000000000003ffff RDI: ffffffff812f51e5
RBP: ffffc90002fe79d0 R08: ffffffff8186f6a0 R09: ffffed100cbd4001
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: 1ffff920005fcf2c R14: ffffc90002fe7960 R15: 0000000000000200
FS:  00007f7b564476c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002006b000 CR3: 00000000187b4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 __local_bh_enable_ip+0x11f/0x1f0 kernel/softirq.c:371
 fpregs_unlock arch/x86/include/asm/fpu/api.h:78 [inline]
 copy_fpstate_to_sigframe+0x46b/0xb40 arch/x86/kernel/fpu/signal.c:205
 get_sigframe+0x378/0x4b0 arch/x86/kernel/signal.c:295
 __setup_rt_frame arch/x86/kernel/signal.c:471 [inline]
 setup_rt_frame arch/x86/kernel/signal.c:780 [inline]
 handle_signal arch/x86/kernel/signal.c:824 [inline]
 arch_do_signal_or_restart+0x4ac/0x1890 arch/x86/kernel/signal.c:869
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x97/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x5d/0x240 kernel/entry/common.c:307
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f7b57fcf717
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:00007f7b56447038 EFLAGS: 00000246
RAX: 0000000000000013 RBX: 00007f7b58186f80 RCX: 00007f7b57fcf719
RDX: 0000000000000001 RSI: 0000000020001340 RDI: 0000000000000006
RBP: 00007f7b5804232e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f7b58186f80 R15: 00007ffde8b2e508
 </TASK>