[syzbot] INFO: rcu detected stall in newstat

From: syzbot
Date: Tue Aug 03 2021 - 03:55:35 EST


Hello,

syzbot found the following issue on:

HEAD commit: 7e96bf476270 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=111d1e2a300000
kernel config: https://syzkaller.appspot.com/x/.config?x=1dee114394f7d2c2
dashboard link: https://syzkaller.appspot.com/bug?extid=84ef57449019b1be878d
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12f2aac9d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15470c66300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+84ef57449019b1be878d@xxxxxxxxxxxxxxxxxxxxxxxxx

mceusb 2-1:0.0: Error: urb status = -71
mceusb 5-1:0.0: Error: urb status = -71
mceusb 2-1:0.0: Error: urb status = -71
mceusb 5-1:0.0: Error: urb status = -71
mceusb 2-1:0.0: Error: urb status = -71
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
(detected by 1, t=10502 jiffies, g=13449, q=1758)
rcu: All QSes seen, last rcu_preempt kthread activity 6502 (4295042261-4295035759), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 6502 jiffies! g13449 f0x2 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:29096 pid: 14 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:4683 [inline]
__schedule+0x93a/0x26f0 kernel/sched/core.c:5940
schedule+0xd3/0x270 kernel/sched/core.c:6019
schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1879
rcu_gp_fqs_loop kernel/rcu/tree.c:1996 [inline]
rcu_gp_kthread+0xd34/0x1980 kernel/rcu/tree.c:2169
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
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: 8589 Comm: systemd-udevd Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:halt arch/x86/include/asm/irqflags.h:99 [inline]
RIP: 0010:kvm_wait+0xbb/0xf0 arch/x86/kernel/kvm.c:883
Code: 5b d9 47 00 8b 74 24 0c 48 8b 3c 24 eb 82 e8 6c de 47 00 eb 07 0f 00 2d c3 d3 55 08 fb f4 eb 9b eb 07 0f 00 2d b6 d3 55 08 f4 <eb> c5 89 74 24 0c 48 89 3c 24 e8 36 74 87 00 8b 74 24 0c 48 8b 3c
RSP: 0018:ffffc90001b87660 EFLAGS: 00000046
RAX: 0000000000000003 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffffffff8b981e40
RBP: ffffffff8b981e40 R08: 0000000000000001 R09: ffffffff8b981e40
R10: fffffbfff17303c8 R11: 0000000000000001 R12: 0000000000000000
R13: fffffbfff17303c8 R14: 0000000000000001 R15: ffff8880b9c52980
FS: 00007f48df6fe8c0(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff47502b08 CR3: 00000000141f0000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
pv_wait arch/x86/include/asm/paravirt.h:597 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
__pv_queued_spin_lock_slowpath+0x8b8/0xb40 kernel/locking/qspinlock.c:508
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
do_raw_spin_lock+0x200/0x2b0 kernel/locking/spinlock_debug.c:113
rcu_note_context_switch+0x294/0x16e0 kernel/rcu/tree_plugin.h:355
__schedule+0x21f/0x26f0 kernel/sched/core.c:5837
preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:6328
irqentry_exit+0x31/0x80 kernel/entry/common.c:427
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__sanitizer_cov_trace_const_cmp1+0x77/0x80 kernel/kcov.c:272
Code: f0 72 27 41 0f b6 fb 41 0f b6 c9 48 83 c2 01 48 c7 44 30 e0 01 00 00 00 48 89 7c 30 e8 48 89 4c 30 f0 4c 89 54 d8 20 48 89 10 <5b> c3 0f 1f 80 00 00 00 00 53 41 89 fb 41 89 f1 bf 03 00 00 00 65
RSP: 0018:ffffc90001b87a18 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000075 RCX: ffff8880361be2c0
RDX: 0000000000000000 RSI: ffff8880361be2c0 RDI: 0000000000000003
RBP: 000000031dee9eb7 R08: 0000000000000000 R09: 0000000000000075
R10: ffffffff81c97ccd R11: 0000000000000000 R12: ffffc90001b87bec
R13: e2f55236f51925a6 R14: ffffc90001b87bb0 R15: ffff8880342d0825
link_path_walk.part.0+0x73d/0xd00 fs/namei.c:2272
link_path_walk fs/namei.c:2210 [inline]
path_lookupat+0xc8/0x860 fs/namei.c:2437
filename_lookup+0x1c6/0x5b0 fs/namei.c:2467
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0x142/0x390 fs/stat.c:203
vfs_fstatat fs/stat.c:225 [inline]
vfs_stat include/linux/fs.h:3382 [inline]
__do_sys_newstat+0x91/0x110 fs/stat.c:367
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+0x44/0xae
RIP: 0033:0x7f48de570295
Code: 00 00 00 e8 5d 01 00 00 48 83 c4 18 c3 0f 1f 84 00 00 00 00 00 83 ff 01 48 89 f0 77 30 48 89 c7 48 89 d6 b8 04 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 03 f3 c3 90 48 8b 15 d1 db 2b 00 f7 d8 64 89
RSP: 002b:00007fff47503388 EFLAGS: 00000246 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000559e49eea790 RCX: 00007f48de570295
RDX: 00007fff47503390 RSI: 00007fff47503390 RDI: 00007fff47503440
RBP: 00007fff475034b0 R08: 000000000000c0c0 R09: 0000000000000000
R10: 00007fff475034c0 R11: 0000000000000246 R12: 00007fff475034c0
R13: 0000000000000001 R14: 0000559e49ed7a40 R15: 000000000000000e

================================
WARNING: inconsistent lock state
5.14.0-rc3-syzkaller #0 Not tainted
--------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
ksoftirqd/1/19 [HC0[0]:SC1[1]:HE0:SE0] takes:
ffffffff8b981e58 (rcu_node_0){?.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:543 [inline]
ffffffff8b981e58 (rcu_node_0){?.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:709 [inline]
ffffffff8b981e58 (rcu_node_0){?.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3922 [inline]
ffffffff8b981e58 (rcu_node_0){?.-.}-{2:2}, at: rcu_sched_clock_irq+0xc9a/0x20c0 kernel/rcu/tree.c:2641
{IN-HARDIRQ-W} state was registered at:
lock_acquire kernel/locking/lockdep.c:5625 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
rcu_report_exp_cpu_mult+0x1c/0x280 kernel/rcu/tree_exp.h:237
flush_smp_call_function_queue+0x34b/0x640 kernel/smp.c:663
__sysvec_call_function_single+0x95/0x3d0 arch/x86/kernel/smp.c:248
sysvec_call_function_single+0x8e/0xc0 arch/x86/kernel/smp.c:243
asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:646
lock_acquire+0x1ef/0x510 kernel/locking/lockdep.c:5593
down_write_killable+0x95/0x170 kernel/locking/rwsem.c:1417
mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
__bprm_mm_init fs/exec.c:257 [inline]
bprm_mm_init fs/exec.c:376 [inline]
alloc_bprm+0x3be/0x8f0 fs/exec.c:1521
kernel_execve+0x55/0x460 fs/exec.c:1941
call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
irq event stamp: 428515
hardirqs last enabled at (428514): [<ffffffff892ce380>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
hardirqs last enabled at (428514): [<ffffffff892ce380>] _raw_spin_unlock_irqrestore+0x50/0x70 kernel/locking/spinlock.c:191
hardirqs last disabled at (428515): [<ffffffff892a264b>] sysvec_apic_timer_interrupt+0xb/0xc0 arch/x86/kernel/apic/apic.c:1100
softirqs last enabled at (392664): [<ffffffff81456d5d>] run_ksoftirqd kernel/softirq.c:920 [inline]
softirqs last enabled at (392664): [<ffffffff81456d5d>] run_ksoftirqd+0x2d/0x60 kernel/softirq.c:912
softirqs last disabled at (392669): [<ffffffff81456d5d>] run_ksoftirqd kernel/softirq.c:920 [inline]
softirqs last disabled at (392669): [<ffffffff81456d5d>] run_ksoftirqd+0x2d/0x60 kernel/softirq.c:912

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(rcu_node_0);
<Interrupt>
lock(rcu_node_0);

*** DEADLOCK ***

2 locks held by ksoftirqd/1/19:
#0: ffffc90000fafc58 ((&dum_hcd->timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:35 [inline]
#0: ffffc90000fafc58 ((&dum_hcd->timer)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x6b0 kernel/time/timer.c:1409
#1: ffffffff8b981e58 (rcu_node_0){?.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:543 [inline]
#1: ffffffff8b981e58 (rcu_node_0){?.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:709 [inline]
#1: ffffffff8b981e58 (rcu_node_0){?.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3922 [inline]
#1: ffffffff8b981e58 (rcu_node_0){?.-.}-{2:2}, at: rcu_sched_clock_irq+0xc9a/0x20c0 kernel/rcu/tree.c:2641

stack backtrace:
CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
print_usage_bug kernel/locking/lockdep.c:203 [inline]
valid_state kernel/locking/lockdep.c:3933 [inline]
mark_lock_irq kernel/locking/lockdep.c:4136 [inline]
mark_lock.cold+0x61/0x8e kernel/locking/lockdep.c:4593
mark_held_locks+0x9f/0xe0 kernel/locking/lockdep.c:4194
__trace_hardirqs_on_caller kernel/locking/lockdep.c:4212 [inline]
lockdep_hardirqs_on_prepare kernel/locking/lockdep.c:4280 [inline]
lockdep_hardirqs_on_prepare+0x135/0x400 kernel/locking/lockdep.c:4232
trace_hardirqs_on+0x5b/0x1c0 kernel/trace/trace_preemptirq.c:49
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:191
Code: 74 24 10 e8 5a 65 2d f8 48 89 ef e8 02 db 2d f8 81 e3 00 02 00 00 75 25 9c 58 f6 c4 02 75 2d 48 85 db 74 01 fb bf 01 00 00 00 <e8> 43 b5 21 f8 65 8b 05 4c 0c d5 76 85 c0 74 0a 5b 5d c3 e8 e0 10
RSP: 0018:ffffc90000faf9f0 EFLAGS: 00000206
RAX: 0000000000000006 RBX: 0000000000000200 RCX: 1ffffffff1fa5092
RDX: 0000000000000000 RSI: 0000000000000101 RDI: 0000000000000001
RBP: ffff888021db8000 R08: 0000000000000001 R09: ffffffff8fcd9977
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888146dbe440
R13: ffff888016ba9600 R14: dffffc0000000000 R15: ffff8880242d7900
spin_unlock_irqrestore include/linux/spinlock.h:409 [inline]
dummy_timer+0x12f6/0x32b0 drivers/usb/gadget/udc/dummy_hcd.c:2001
call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1419
expire_timers kernel/time/timer.c:1464 [inline]
__run_timers.part.0+0x675/0xa50 kernel/time/timer.c:1732
__run_timers kernel/time/timer.c:1713 [inline]
run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1745
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558
run_ksoftirqd kernel/softirq.c:920 [inline]
run_ksoftirqd+0x2d/0x60 kernel/softirq.c:912
smpboot_thread_fn+0x645/0x9c0 kernel/smpboot.c:164
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
------------[ cut here ]------------
timer: dummy_timer+0x0/0x32b0 include/linux/list.h:112 preempt leak: 00000100 -> 00000101
WARNING: CPU: 1 PID: 19 at kernel/time/timer.c:1425 call_timer_fn+0x664/0x6b0 kernel/time/timer.c:1425
Modules linked in:
CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:call_timer_fn+0x664/0x6b0 kernel/time/timer.c:1425
Code: e8 41 ae 10 00 89 da 4c 89 f6 48 c7 c7 a0 9d 8d 89 65 8b 0d 1e cd 9d 7e 81 e1 ff ff ff 7f c6 05 b0 ae f3 0b 01 e8 b7 b8 83 07 <0f> 0b e9 f4 fb ff ff e8 10 ae 10 00 0f 0b e9 6f fd ff ff e8 04 ae
RSP: 0018:ffffc90000fafc20 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000100 RCX: 0000000000000000
RDX: ffff888011e54140 RSI: ffffffff815cad15 RDI: fffff520001f5f76
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815c4b1e R11: 0000000000000000 R12: 0000000000000000
R13: 1ffff920001f5f85 R14: ffffffff859db710 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb590071168 CR3: 000000001842b000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
expire_timers kernel/time/timer.c:1464 [inline]
__run_timers.part.0+0x675/0xa50 kernel/time/timer.c:1732
__run_timers kernel/time/timer.c:1713 [inline]
run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1745
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558
run_ksoftirqd kernel/softirq.c:920 [inline]
run_ksoftirqd+0x2d/0x60 kernel/softirq.c:912
smpboot_thread_fn+0x645/0x9c0 kernel/smpboot.c:164
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches