Re: [syzbot] [bpf?] [trace?] possible deadlock in task_fork_fair

From: syzbot
Date: Mon Dec 11 2023 - 20:01:39 EST

Next message: Chao Yu: "[PATCH v2 4/6] f2fs: don't set FI_PREALLOCATED_ALL for partial write"
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Next in thread: syzbot: "Re: [syzbot] [bpf?] [trace?] possible deadlock in task_fork_fair"
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syzbot has found a reproducer for the following issue on:

HEAD commit: 2ebe81c81435 net, xdp: Allow metadata > 32
git tree: bpf-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16687bdee80000
kernel config: https://syzkaller.appspot.com/x/.config?x=f8715b6ede5c4b90
dashboard link: https://syzkaller.appspot.com/bug?extid=1a93ee5d329e97cfbaff
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=148b2632e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11aae88ee80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/972e21c08639/disk-2ebe81c8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c55f0d0739c1/vmlinux-2ebe81c8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4aa04cd001b3/bzImage-2ebe81c8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1a93ee5d329e97cfbaff@xxxxxxxxxxxxxxxxxxxxxxxxx

FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 1
======================================================
WARNING: possible circular locking dependency detected
6.7.0-rc3-syzkaller-00778-g2ebe81c81435 #0 Not tainted
------------------------------------------------------
syz-executor229/5088 is trying to acquire lock:
ffffffff8ceb8da0 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1962 [inline]
ffffffff8ceb8da0 (console_owner){....}-{0:0}, at: vprintk_emit+0x313/0x5f0 kernel/printk/printk.c:2302

but task is already holding lock:
ffff8880b983c718 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:558

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #5 (&rq->__lock){-.-.}-{2:2}:
_raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:558
raw_spin_rq_lock kernel/sched/sched.h:1349 [inline]
rq_lock kernel/sched/sched.h:1663 [inline]
task_fork_fair+0x70/0x240 kernel/sched/fair.c:12586
sched_cgroup_fork+0x3cf/0x510 kernel/sched/core.c:4812
copy_process+0x4c86/0x73f0 kernel/fork.c:2609
kernel_clone+0xfd/0x930 kernel/fork.c:2907
user_mode_thread+0xb4/0xf0 kernel/fork.c:2985
rest_init+0x27/0x2b0 init/main.c:695
arch_call_rest_init+0x13/0x30 init/main.c:827
start_kernel+0x39f/0x480 init/main.c:1072
x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:555
x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:536
secondary_startup_64_no_verify+0x166/0x16b

-> #4 (&p->pi_lock){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:518 [inline]
try_to_wake_up+0xb0/0x13d0 kernel/sched/core.c:4226
kick_pool+0x253/0x470 kernel/workqueue.c:1142
create_worker+0x46f/0x730 kernel/workqueue.c:2217
workqueue_init+0x319/0x830 kernel/workqueue.c:6698
kernel_init_freeable+0x332/0xc10 init/main.c:1536
kernel_init+0x1c/0x2a0 init/main.c:1441
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

-> #3 (&pool->lock){-.-.}-{2:2}:
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
__queue_work+0x399/0x11f0 kernel/workqueue.c:1763
queue_work_on+0xed/0x110 kernel/workqueue.c:1834
queue_work include/linux/workqueue.h:562 [inline]
rpm_suspend+0x121b/0x16f0 drivers/base/power/runtime.c:660
rpm_idle+0x578/0x6e0 drivers/base/power/runtime.c:534
__pm_runtime_idle+0xbe/0x160 drivers/base/power/runtime.c:1102
pm_runtime_put include/linux/pm_runtime.h:460 [inline]
__device_attach+0x382/0x4b0 drivers/base/dd.c:1048
bus_probe_device+0x17c/0x1c0 drivers/base/bus.c:532
device_add+0x117e/0x1aa0 drivers/base/core.c:3625
serial_base_port_add+0x353/0x4b0 drivers/tty/serial/serial_base_bus.c:178
serial_core_port_device_add drivers/tty/serial/serial_core.c:3316 [inline]
serial_core_register_port+0x137/0x1af0 drivers/tty/serial/serial_core.c:3357
serial8250_register_8250_port+0x140d/0x2080 drivers/tty/serial/8250/8250_core.c:1139
serial_pnp_probe+0x47d/0x880 drivers/tty/serial/8250/8250_pnp.c:478
pnp_device_probe+0x2a3/0x4c0 drivers/pnp/driver.c:111
call_driver_probe drivers/base/dd.c:579 [inline]
really_probe+0x234/0xc90 drivers/base/dd.c:658
__driver_probe_device+0x1de/0x4b0 drivers/base/dd.c:800
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:830
__driver_attach+0x274/0x570 drivers/base/dd.c:1216
bus_for_each_dev+0x13c/0x1d0 drivers/base/bus.c:368
bus_add_driver+0x2e9/0x630 drivers/base/bus.c:673
driver_register+0x15c/0x4a0 drivers/base/driver.c:246
serial8250_init+0xba/0x4b0 drivers/tty/serial/8250/8250_core.c:1240
do_one_initcall+0x11c/0x650 init/main.c:1236
do_initcall_level init/main.c:1298 [inline]
do_initcalls init/main.c:1314 [inline]
do_basic_setup init/main.c:1333 [inline]
kernel_init_freeable+0x687/0xc10 init/main.c:1551
kernel_init+0x1c/0x2a0 init/main.c:1441
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

-> #2 (&dev->power.lock){-...}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
__pm_runtime_resume+0xab/0x170 drivers/base/power/runtime.c:1169
pm_runtime_get include/linux/pm_runtime.h:408 [inline]
__uart_start+0x1b2/0x470 drivers/tty/serial/serial_core.c:148
uart_write+0x2ff/0x5b0 drivers/tty/serial/serial_core.c:616
process_output_block drivers/tty/n_tty.c:574 [inline]
n_tty_write+0x422/0x1130 drivers/tty/n_tty.c:2379
iterate_tty_write drivers/tty/tty_io.c:1021 [inline]
file_tty_write.constprop.0+0x519/0x9b0 drivers/tty/tty_io.c:1092
tty_write drivers/tty/tty_io.c:1113 [inline]
redirected_tty_write drivers/tty/tty_io.c:1136 [inline]
redirected_tty_write+0xa6/0xc0 drivers/tty/tty_io.c:1116
call_write_iter include/linux/fs.h:2020 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x64f/0xdf0 fs/read_write.c:584
ksys_write+0x12f/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #1 (&port_lock_key){-...}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
uart_port_lock_irqsave include/linux/serial_core.h:616 [inline]
serial8250_console_write+0xa7c/0x1060 drivers/tty/serial/8250/8250_port.c:3403
console_emit_next_record kernel/printk/printk.c:2901 [inline]
console_flush_all+0x4d5/0xd60 kernel/printk/printk.c:2967
console_unlock+0x10c/0x260 kernel/printk/printk.c:3036
vprintk_emit+0x17f/0x5f0 kernel/printk/printk.c:2303
vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45
_printk+0xc8/0x100 kernel/printk/printk.c:2328
register_console+0xa74/0x1060 kernel/printk/printk.c:3542
univ8250_console_init+0x35/0x50 drivers/tty/serial/8250/8250_core.c:717
console_init+0xba/0x5d0 kernel/printk/printk.c:3688
start_kernel+0x25a/0x480 init/main.c:1008
x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:555
x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:536
secondary_startup_64_no_verify+0x166/0x16b

-> #0 (console_owner){....}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
console_trylock_spinning kernel/printk/printk.c:1962 [inline]
vprintk_emit+0x328/0x5f0 kernel/printk/printk.c:2302
vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45
_printk+0xc8/0x100 kernel/printk/printk.c:2328
fail_dump lib/fault-inject.c:45 [inline]
should_fail_ex+0x46b/0x5b0 lib/fault-inject.c:153
strncpy_from_user+0x38/0x300 lib/strncpy_from_user.c:118
strncpy_from_user_nofault+0x80/0x180 mm/maccess.c:186
bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:213 [inline]
____bpf_probe_read_user_str kernel/trace/bpf_trace.c:222 [inline]
bpf_probe_read_user_str+0x26/0x70 kernel/trace/bpf_trace.c:219
bpf_prog_6fb7ada547f278f2+0x3d/0x3f
bpf_dispatcher_nop_func include/linux/bpf.h:1219 [inline]
__bpf_prog_run include/linux/filter.h:651 [inline]
bpf_prog_run include/linux/filter.h:658 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2378 [inline]
bpf_trace_run4+0x173/0x450 kernel/trace/bpf_trace.c:2419
__bpf_trace_sched_switch+0x13e/0x180 include/trace/events/sched.h:222
__traceiter_sched_switch+0x6c/0xc0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x21f3/0x5af0 kernel/sched/core.c:6685
__schedule_loop kernel/sched/core.c:6763 [inline]
schedule+0xe9/0x270 kernel/sched/core.c:6778
ptrace_stop.part.0+0x44d/0x7a0 kernel/signal.c:2353
ptrace_stop kernel/signal.c:2255 [inline]
ptrace_do_notify+0x22f/0x2e0 kernel/signal.c:2390
ptrace_notify+0xc8/0x130 kernel/signal.c:2402
ptrace_report_syscall include/linux/ptrace.h:411 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:473 [inline]
syscall_exit_work kernel/entry/common.c:251 [inline]
syscall_exit_to_user_mode_prepare+0x126/0x230 kernel/entry/common.c:278
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0xe/0x60 kernel/entry/common.c:296
do_syscall_64+0x4d/0x110 arch/x86/entry/common.c:88
entry_SYSCALL_64_after_hwframe+0x63/0x6b

other info that might help us debug this:

Chain exists of:
console_owner --> &p->pi_lock --> &rq->__lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&rq->__lock);
lock(&p->pi_lock);
lock(&rq->__lock);
lock(console_owner);

*** DEADLOCK ***

2 locks held by syz-executor229/5088:
#0: ffff8880b983c718 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:558
#1: ffffffff8cfabbe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline]
#1: ffffffff8cfabbe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]
#1: ffffffff8cfabbe0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2377 [inline]
#1: ffffffff8cfabbe0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run4+0x107/0x450 kernel/trace/bpf_trace.c:2419

stack backtrace:
CPU: 0 PID: 5088 Comm: syz-executor229 Not tainted 6.7.0-rc3-syzkaller-00778-g2ebe81c81435 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
check_noncircular+0x317/0x400 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
console_trylock_spinning kernel/printk/printk.c:1962 [inline]
vprintk_emit+0x328/0x5f0 kernel/printk/printk.c:2302
vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45
_printk+0xc8/0x100 kernel/printk/printk.c:2328
fail_dump lib/fault-inject.c:45 [inline]
should_fail_ex+0x46b/0x5b0 lib/fault-inject.c:153
strncpy_from_user+0x38/0x300 lib/strncpy_from_user.c:118
strncpy_from_user_nofault+0x80/0x180 mm/maccess.c:186
bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:213 [inline]
____bpf_probe_read_user_str kernel/trace/bpf_trace.c:222 [inline]
bpf_probe_read_user_str+0x26/0x70 kernel/trace/bpf_trace.c:219
bpf_prog_6fb7ada547f278f2+0x3d/0x3f
bpf_dispatcher_nop_func include/linux/bpf.h:1219 [inline]
__bpf_prog_run include/linux/filter.h:651 [inline]
bpf_prog_run include/linux/filter.h:658 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2378 [inline]
bpf_trace_run4+0x173/0x450 kernel/trace/bpf_trace.c:2419
__bpf_trace_sched_switch+0x13e/0x180 include/trace/events/sched.h:222
__traceiter_sched_switch+0x6c/0xc0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x21f3/0x5af0 kernel/sched/core.c:6685
__schedule_loop kernel/sched/core.c:6763 [inline]
schedule+0xe9/0x270 kernel/sched/core.c:6778
ptrace_stop.part.0+0x44d/0x7a0 kernel/signal.c:2353
ptrace_stop kernel/signal.c:2255 [inline]
ptrace_do_notify+0x22f/0x2e0 kernel/signal.c:2390
ptrace_notify+0xc8/0x130 kernel/signal.c:2402
ptrace_report_syscall include/linux/ptrace.h:411 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:473 [inline]
syscall_exit_work kernel/entry/common.c:251 [inline]
syscall_exit_to_user_mode_prepare+0x126/0x230 kernel/entry/common.c:278
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0xe/0x60 kernel/entry/common.c:296
do_syscall_64+0x4d/0x110 arch/x86/entry/common.c:88
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7fc3b1ed34f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 00 00 90 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:00007ffdaa3d0328 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: 00000000000000d8 RBX: 0000000000000000 RCX: 00007fc3b1ed34f9
RDX: 0000000000000000 RSI: 0000000020000940 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffdaa3d00c6 R09: 00000000557624c0
R10: 0000000000000002 R11: 0000000000000246 R12: 00000000200000d8
R13: 00007ffdaa3d0334 R14: 0000000000000000 R15: 00007ffdaa3d0350
</TASK>
CPU: 0 PID: 5088 Comm: syz-executor229 Not tainted 6.7.0-rc3-syzkaller-00778-g2ebe81c81435 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
fail_dump lib/fault-inject.c:52 [inline]
should_fail_ex+0x496/0x5b0 lib/fault-inject.c:153
strncpy_from_user+0x38/0x300 lib/strncpy_from_user.c:118
strncpy_from_user_nofault+0x80/0x180 mm/maccess.c:186
bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:213 [inline]
____bpf_probe_read_user_str kernel/trace/bpf_trace.c:222 [inline]
bpf_probe_read_user_str+0x26/0x70 kernel/trace/bpf_trace.c:219
bpf_prog_6fb7ada547f278f2+0x3d/0x3f
bpf_dispatcher_nop_func include/linux/bpf.h:1219 [inline]
__bpf_prog_run include/linux/filter.h:651 [inline]
bpf_prog_run include/linux/filter.h:658 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2378 [inline]
bpf_trace_run4+0x173/0x450 kernel/trace/bpf_trace.c:2419
__bpf_trace_sched_switch+0x13e/0x180 include/trace/events/sched.h:222
__traceiter_sched_switch+0x6c/0xc0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x21f3/0x5af0 kernel/sched/core.c:6685
__schedule_loop kernel/sched/core.c:6763 [inline]
schedule+0xe9/0x270 kernel/sched/core.c:6778
ptrace_stop.part.0+0x44d/0x7a0 kernel/signal.c:2353
ptrace_stop kernel/signal.c:2255 [inline]
ptrace_do_notify+0x22f/0x2e0 kernel/signal.c:2390
ptrace_notify+0xc8/0x130 kernel/signal.c:2402
ptrace_report_syscall include/linux/ptrace.h:411 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:473 [inline]
syscall_exit_work kernel/entry/common.c:251 [inline]
syscall_exit_to_user_mode_prepare+0x126/0x230 kernel/entry/common.c:278
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0xe/0x60 kernel/entry/common.c:296
do_syscall_64+0x4d/0x110 arch/x86/entry/common.c:88
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7fc3b1ed34f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 00 00 90 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:00007ffdaa3d0328 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: 00000000000000d8 RBX: 0000000000000000 RCX: 00007fc3b1ed34f9
RDX: 0000000000000000 RSI: 0000000020000940 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffdaa3d00c6 R09: 00000000557624c0
R10: 0000000000000002 R11: 0000000000000246 R12: 00000000200000d8
R13: 00007ffdaa3d0334 R14: 0000000000000000 R15: 00007ffdaa3d0350
</TASK>

---
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#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

Next message: Chao Yu: "[PATCH v2 4/6] f2fs: don't set FI_PREALLOCATED_ALL for partial write"
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