syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 0, t=10502 jiffies, g=29201, q=10 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294993945-4294983443), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g29201 f0x2 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:28304 pid:   16 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5182 [inline]
 __schedule+0xadf/0x52b0 kernel/sched/core.c:6494
 schedule+0xda/0x1b0 kernel/sched/core.c:6570
 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1935
 rcu_gp_fqs_loop+0x190/0x910 kernel/rcu/tree.c:1657
 rcu_gp_kthread+0x236/0x360 kernel/rcu/tree.c:1854
 kthread+0x2e4/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </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 PID: 7676 Comm: syz-executor.5 Not tainted 6.0.0-rc2-syzkaller-00159-g4c612826bec1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:3723 [inline]
RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3742 [inline]
RIP: 0010:validate_chain kernel/locking/lockdep.c:3797 [inline]
RIP: 0010:__lock_acquire+0x16ff/0x56d0 kernel/locking/lockdep.c:5053
Code: 49 be 00 00 00 00 00 fc ff df 48 89 ea 48 8b 6c 24 08 eb 06 48 83 eb 08 74 42 48 8d 7b 18 48 89 f8 48 c1 e8 03 42 80 3c 30 00 <0f> 85 75 3f 00 00 48 8b 43 18 48 39 c5 0f 84 99 f5 ff ff 48 8d 7b
RSP: 0018:ffffc900003f8ae8 EFLAGS: 00000046
RAX: 1ffffffff1ef5493 RBX: ffffffff8f7aa480 RCX: ffffffff815e550e
RDX: 0000000000018332 RSI: 0000000000000008 RDI: ffffffff8f7aa498
RBP: a44371ab51f8558f R08: 0000000000000000 R09: ffffffff908da947
R10: fffffbfff211b528 R11: 0000000000000000 R12: ffff88801d926c80
R13: ffff88801d926140 R14: dffffc0000000000 R15: 0000000000000000
FS:  00007fc23694e700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2e227000 CR3: 0000000077a92000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lock_acquire kernel/locking/lockdep.c:5666 [inline]
 lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
 debug_object_deactivate lib/debugobjects.c:732 [inline]
 debug_object_deactivate+0x101/0x300 lib/debugobjects.c:720
 debug_hrtimer_deactivate kernel/time/hrtimer.c:425 [inline]
 debug_deactivate kernel/time/hrtimer.c:481 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1653 [inline]
 __hrtimer_run_queues+0x3f3/0xe40 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1095 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1112
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1106
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:166 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:200
Code: 48 89 ef 5d e9 b1 25 4b 00 5d be 03 00 00 00 e9 36 d8 81 02 66 0f 1f 44 00 00 48 8b be a8 01 00 00 e8 b4 ff ff ff 31 c0 c3 90 <65> 8b 05 09 35 87 7e 89 c1 48 8b 34 24 81 e1 00 01 00 00 65 48 8b
RSP: 0018:ffffc900031f73a8 EFLAGS: 00000246
RAX: 0000000000040000 RBX: ffffc900031f7640 RCX: ffffc900044d2000
RDX: 0000000000040000 RSI: ffffffff821d073f RDI: 0000000000000001
RBP: ffffea0001d427c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 000000000008c07c R12: ffff888020f34000
R13: ffff88801eb50370 R14: 0000000000000008 R15: 0000000000000001
 _compound_head include/linux/page-flags.h:253 [inline]
 PageUptodate include/linux/page-flags.h:730 [inline]
 ext4_mb_load_buddy_gfp+0x4ab/0x1350 fs/ext4/mballoc.c:1552
 ext4_mb_load_buddy fs/ext4/mballoc.c:1613 [inline]
 ext4_mb_find_by_goal+0x200/0x1010 fs/ext4/mballoc.c:2213
 ext4_mb_regular_allocator+0x237/0x3610 fs/ext4/mballoc.c:2657
 ext4_mb_new_blocks+0x235f/0x5020 fs/ext4/mballoc.c:5643
 ext4_ext_map_blocks+0x2179/0x5f50 fs/ext4/extents.c:4281
 ext4_map_blocks+0x775/0x18d0 fs/ext4/inode.c:645
 ext4_alloc_file_blocks.isra.0+0x2c1/0xae0 fs/ext4/extents.c:4466
 ext4_zero_range fs/ext4/extents.c:4583 [inline]
 ext4_fallocate+0x1332/0x4020 fs/ext4/extents.c:4718
 vfs_fallocate+0x487/0xe00 fs/open.c:323
 ksys_fallocate fs/open.c:346 [inline]
 __do_sys_fallocate fs/open.c:354 [inline]
 __se_sys_fallocate fs/open.c:352 [inline]
 __x64_sys_fallocate+0xcf/0x140 fs/open.c:352
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fc235889279
Code: 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc23694e168 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007fc23599bf80 RCX: 00007fc235889279
RDX: 0000000000000000 RSI: 0000000100000011 RDI: 0000000000000003
RBP: 00007fc2358e3189 R08: 0000000000000000 R09: 0000000000000000
R10: 000000002811fdff R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe4f02c60f R14: 00007fc23694e300 R15: 0000000000022000
 </TASK>