[syzbot] [bpf?] possible deadlock in work_grab_pending

syzbot
2024-08-22T08:45:30Z

Hello,

syzbot found the following issue on:

HEAD commit: 367b5c3d53e5 Add linux-next specific files for 20240816
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1567fde5980000
kernel config: https://syzkaller.appspot.com/x/.config?x=61ba6f3b22ee5467
dashboard link: https://syzkaller.appspot.com/bug?extid=fbf8ab9c22c12e84f438
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0b1b4e3cad3c/disk-367b5c3d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5bb090f7813c/vmlinux-367b5c3d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6674cb0709b1/bzImage-367b5c3d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fbf8ab9c22c12e84f438@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.11.0-rc3-next-20240816-syzkaller #0 Not tainted
------------------------------------------------------
swapper/1/0 is trying to acquire lock:
ffff8880158a0018 (&pool->lock){-.-.}-{2:2}, at: try_to_grab_pending kernel/workqueue.c:2084 [inline]
ffff8880158a0018 (&pool->lock){-.-.}-{2:2}, at: work_grab_pending+0x294/0xae0 kernel/workqueue.c:2160

but task is already holding lock:
ffff8880b9129430 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3312 [inline]
ffff8880b9129430 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3724 [inline]
ffff8880b9129430 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3810

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (krc.lock){..-.}-{2:2}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5762
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
krc_this_cpu_lock kernel/rcu/tree.c:3312 [inline]
add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3724 [inline]
kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3810
trie_delete_elem+0x546/0x6a0 kernel/bpf/lpm_trie.c:540
0xffffffffa0001fe3
bpf_dispatcher_nop_func include/linux/bpf.h:1252 [inline]
__bpf_prog_run include/linux/filter.h:691 [inline]
bpf_prog_run include/linux/filter.h:698 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2338 [inline]
bpf_trace_run4+0x334/0x590 kernel/trace/bpf_trace.c:2381
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x2591/0x4ad0 kernel/sched/core.c:6636
preempt_schedule_common+0x84/0xd0 kernel/sched/core.c:6818
preempt_schedule+0xe1/0xf0 kernel/sched/core.c:6842
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12
class_preempt_destructor include/linux/preempt.h:480 [inline]
try_to_wake_up+0x9a1/0x1470 kernel/sched/core.c:4236
wake_up_process kernel/sched/core.c:4361 [inline]
wake_up_q+0xc8/0x120 kernel/sched/core.c:1056
futex_wake+0x523/0x5c0 kernel/futex/waitwake.c:199
do_futex+0x392/0x560 kernel/futex/syscalls.c:107
__do_sys_futex kernel/futex/syscalls.c:179 [inline]
__se_sys_futex+0x3f9/0x480 kernel/futex/syscalls.c:160
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&rq->__lock){-.-.}-{2:2}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5762
_raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:587
raw_spin_rq_lock kernel/sched/sched.h:1485 [inline]
task_rq_lock+0xc6/0x360 kernel/sched/core.c:689
cgroup_move_task+0x92/0x2d0 kernel/sched/psi.c:1161
css_set_move_task+0x72e/0x950 kernel/cgroup/cgroup.c:898
cgroup_post_fork+0x256/0x880 kernel/cgroup/cgroup.c:6690
copy_process+0x3ab1/0x3e30 kernel/fork.c:2620
kernel_clone+0x226/0x8f0 kernel/fork.c:2806
user_mode_thread+0x132/0x1a0 kernel/fork.c:2884
rest_init+0x23/0x300 init/main.c:712
start_kernel+0x47a/0x500 init/main.c:1103
x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:507
x86_64_start_kernel+0x9f/0xa0 arch/x86/kernel/head64.c:488
common_startup_64+0x13e/0x147

-> #1 (&p->pi_lock){-.-.}-{2:2}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5762
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline]
try_to_wake_up+0xb0/0x1470 kernel/sched/core.c:4113
create_worker+0x507/0x720 kernel/workqueue.c:2828
workqueue_init+0x520/0x8a0 kernel/workqueue.c:7902
kernel_init_freeable+0x3fe/0x5d0 init/main.c:1562
kernel_init+0x1d/0x2b0 init/main.c:1467
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (&pool->lock){-.-.}-{2:2}:
check_prev_add kernel/locking/lockdep.c:3136 [inline]
check_prevs_add kernel/locking/lockdep.c:3255 [inline]
validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3871
__lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5145
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5762
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
try_to_grab_pending kernel/workqueue.c:2084 [inline]
work_grab_pending+0x294/0xae0 kernel/workqueue.c:2160
mod_delayed_work_on+0xd4/0x370 kernel/workqueue.c:2588
kvfree_call_rcu+0x47f/0x790 kernel/rcu/tree.c:3838
cfg80211_update_known_bss+0xb39/0x1500 net/wireless/scan.c:1891
__cfg80211_bss_update+0x153/0x2170 net/wireless/scan.c:1937
cfg80211_inform_single_bss_data+0xd51/0x2030 net/wireless/scan.c:2331
cfg80211_inform_bss_data+0x3dd/0x5a70 net/wireless/scan.c:3159
cfg80211_inform_bss_frame_data+0x3b8/0x720 net/wireless/scan.c:3254
ieee80211_bss_info_update+0x8a7/0xbc0 net/mac80211/scan.c:226
ieee80211_scan_rx+0x526/0x9c0 net/mac80211/scan.c:340
__ieee80211_rx_handle_packet net/mac80211/rx.c:5225 [inline]
ieee80211_rx_list+0x2b02/0x3780 net/mac80211/rx.c:5462
ieee80211_rx_napi+0x18a/0x3c0 net/mac80211/rx.c:5485
ieee80211_rx include/net/mac80211.h:5124 [inline]
ieee80211_handle_queued_frames+0xe7/0x1e0 net/mac80211/main.c:439
tasklet_action_common+0x321/0x4d0 kernel/softirq.c:785
handle_softirqs+0x2c4/0x970 kernel/softirq.c:554
__do_softirq kernel/softirq.c:588 [inline]
invoke_softirq kernel/softirq.c:428 [inline]
__irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1037 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1037
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:111
acpi_idle_enter+0xe4/0x140 drivers/acpi/processor_idle.c:702
cpuidle_enter_state+0x112/0x480 drivers/cpuidle/cpuidle.c:267
cpuidle_enter+0x5d/0xa0 drivers/cpuidle/cpuidle.c:388
call_cpuidle kernel/sched/idle.c:155 [inline]
cpuidle_idle_call kernel/sched/idle.c:230 [inline]
do_idle+0x375/0x5d0 kernel/sched/idle.c:326
cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:424
__pfx_ap_starting+0x0/0x10 arch/x86/kernel/smpboot.c:313
common_startup_64+0x13e/0x147

other info that might help us debug this:

Chain exists of:
&pool->lock --> &rq->__lock --> krc.lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(krc.lock);
lock(&rq->__lock);
lock(krc.lock);
lock(&pool->lock);

*** DEADLOCK ***

4 locks held by swapper/1/0:
#0: ffffffff8e939720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
#0: ffffffff8e939720 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8e939720 (rcu_read_lock){....}-{1:2}, at: ieee80211_rx_napi+0xd6/0x3c0 net/mac80211/rx.c:5484
#1: ffff8880799c0168 (&rdev->bss_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
#1: ffff8880799c0168 (&rdev->bss_lock){+.-.}-{2:2}, at: cfg80211_inform_single_bss_data+0xd3d/0x2030 net/wireless/scan.c:2330
#2: ffff8880b9129430 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3312 [inline]
#2: ffff8880b9129430 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3724 [inline]
#2: ffff8880b9129430 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3810
#3: ffffffff8e939720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
#3: ffffffff8e939720 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#3: ffffffff8e939720 (rcu_read_lock){....}-{1:2}, at: try_to_grab_pending kernel/workqueue.c:2075 [inline]
#3: ffffffff8e939720 (rcu_read_lock){....}-{1:2}, at: work_grab_pending+0x1d3/0xae0 kernel/workqueue.c:2160

stack backtrace:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.11.0-rc3-next-20240816-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2189
check_prev_add kernel/locking/lockdep.c:3136 [inline]
check_prevs_add kernel/locking/lockdep.c:3255 [inline]
validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3871
__lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5145
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5762
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
try_to_grab_pending kernel/workqueue.c:2084 [inline]
work_grab_pending+0x294/0xae0 kernel/workqueue.c:2160
mod_delayed_work_on+0xd4/0x370 kernel/workqueue.c:2588
kvfree_call_rcu+0x47f/0x790 kernel/rcu/tree.c:3838
cfg80211_update_known_bss+0xb39/0x1500 net/wireless/scan.c:1891
__cfg80211_bss_update+0x153/0x2170 net/wireless/scan.c:1937
cfg80211_inform_single_bss_data+0xd51/0x2030 net/wireless/scan.c:2331
cfg80211_inform_bss_data+0x3dd/0x5a70 net/wireless/scan.c:3159
cfg80211_inform_bss_frame_data+0x3b8/0x720 net/wireless/scan.c:3254
ieee80211_bss_info_update+0x8a7/0xbc0 net/mac80211/scan.c:226
ieee80211_scan_rx+0x526/0x9c0 net/mac80211/scan.c:340
__ieee80211_rx_handle_packet net/mac80211/rx.c:5225 [inline]
ieee80211_rx_list+0x2b02/0x3780 net/mac80211/rx.c:5462
ieee80211_rx_napi+0x18a/0x3c0 net/mac80211/rx.c:5485
ieee80211_rx include/net/mac80211.h:5124 [inline]
ieee80211_handle_queued_frames+0xe7/0x1e0 net/mac80211/main.c:439
tasklet_action_common+0x321/0x4d0 kernel/softirq.c:785
handle_softirqs+0x2c4/0x970 kernel/softirq.c:554
__do_softirq kernel/softirq.c:588 [inline]
invoke_softirq kernel/softirq.c:428 [inline]
__irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1037 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1037
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:92 [inline]
RIP: 0010:acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:112
Code: 90 90 90 90 90 90 90 90 90 65 48 8b 04 25 80 d7 03 00 48 f7 00 08 00 00 00 75 10 66 90 0f 00 2d d5 69 ae 00 f3 0f 1e fa fb f4 <fa> c3 cc cc cc cc 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90
RSP: 0018:ffffc900001a7d08 EFLAGS: 00000246
RAX: ffff888017ec0000 RBX: ffff88801bea9864 RCX: 000000000019e8c9
RDX: 0000000000000001 RSI: ffff88801bea9800 RDI: ffff88801bea9864
RBP: 000000000003a6f8 R08: ffff8880b9137c7b R09: 1ffff11017226f8f
R10: dffffc0000000000 R11: ffffffff8bbbf1e0 R12: ffff888018b56000
R13: 0000000000000000 R14: 0000000000000001 R15: ffffffff8f0e8660
acpi_idle_enter+0xe4/0x140 drivers/acpi/processor_idle.c:702
cpuidle_enter_state+0x112/0x480 drivers/cpuidle/cpuidle.c:267
cpuidle_enter+0x5d/0xa0 drivers/cpuidle/cpuidle.c:388
call_cpuidle kernel/sched/idle.c:155 [inline]
cpuidle_idle_call kernel/sched/idle.c:230 [inline]
do_idle+0x375/0x5d0 kernel/sched/idle.c:326
cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:424
start_secondary+0x100/0x100 arch/x86/kernel/smpboot.c:313
common_startup_64+0x13e/0x147
</TASK>
----------------
Code disassembly (best guess):
0: 90 nop
1: 90 nop
2: 90 nop
3: 90 nop
4: 90 nop
5: 90 nop
6: 90 nop
7: 90 nop
8: 90 nop
9: 65 48 8b 04 25 80 d7 mov %gs:0x3d780,%rax
10: 03 00
12: 48 f7 00 08 00 00 00 testq $0x8,(%rax)
19: 75 10 jne 0x2b
1b: 66 90 xchg %ax,%ax
1d: 0f 00 2d d5 69 ae 00 verw 0xae69d5(%rip) # 0xae69f9
24: f3 0f 1e fa endbr64
28: fb sti
29: f4 hlt
* 2a: fa cli <-- trapping instruction
2b: c3 ret
2c: cc int3
2d: cc int3
2e: cc int3
2f: cc int3
30: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
37: 00 00
39: 90 nop
3a: 90 nop
3b: 90 nop
3c: 90 nop
3d: 90 nop
3e: 90 nop
3f: 90 nop

---
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