[syzbot] [kernel?] possible deadlock in task_fork_fair

From: syzbot
Date: Sun Oct 08 2023 - 02:28:55 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 7d730f1bf6f3 Add linux-next specific files for 20231005
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1150d0de680000
kernel config: https://syzkaller.appspot.com/x/.config?x=f532286be4fff4b5
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

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1d7f28a4398f/disk-7d730f1b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d454d124268e/vmlinux-7d730f1b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dbca966175cb/bzImage-7d730f1b.xz

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

EEVDF scheduling fail, picking leftmost
======================================================
WARNING: possible circular locking dependency detected
6.6.0-rc4-next-20231005-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/5092 is trying to acquire lock:
ffffffff8cab8560 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1963 [inline]
ffffffff8cab8560 (console_owner){....}-{0:0}, at: vprintk_emit+0x313/0x5f0 kernel/printk/printk.c:2303

but task is already holding lock:
ffff8880b993c718 (&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:1357 [inline]
rq_lock kernel/sched/sched.h:1671 [inline]
task_fork_fair+0x70/0x240 kernel/sched/fair.c:12399
sched_cgroup_fork+0x3cf/0x510 kernel/sched/core.c:4799
copy_process+0x4580/0x74b0 kernel/fork.c:2609
kernel_clone+0xfd/0x920 kernel/fork.c:2907
user_mode_thread+0xb4/0xf0 kernel/fork.c:2985
rest_init+0x27/0x2b0 init/main.c:691
arch_call_rest_init+0x13/0x30 init/main.c:823
start_kernel+0x39f/0x480 init/main.c:1068
x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:556
x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:537
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+0xb0/0x15d0 kernel/sched/core.c:4213
kick_pool+0x253/0x460 kernel/workqueue.c:1142
create_worker+0x45e/0x710 kernel/workqueue.c:2217
workqueue_init+0x319/0x830 kernel/workqueue.c:6686
kernel_init_freeable+0x332/0x900 init/main.c:1532
kernel_init+0x1c/0x2a0 init/main.c:1437
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

-> #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+0x399/0x1050 kernel/workqueue.c:1763
queue_work_on+0xed/0x110 kernel/workqueue.c:1834
queue_work include/linux/workqueue.h:554 [inline]
rpm_suspend+0x1219/0x16f0 drivers/base/power/runtime.c:660
rpm_idle+0x574/0x6e0 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:3624
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:3315 [inline]
serial_core_register_port+0x137/0x1af0 drivers/tty/serial/serial_core.c:3356
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/0x640 init/main.c:1232
do_initcall_level init/main.c:1294 [inline]
do_initcalls init/main.c:1310 [inline]
do_basic_setup init/main.c:1329 [inline]
kernel_init_freeable+0x5c2/0x900 init/main.c:1547
kernel_init+0x1c/0x2a0 init/main.c:1437
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

-> #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+0x1b0/0x420 drivers/tty/serial/serial_core.c:148
uart_write+0x2ff/0x5b0 drivers/tty/serial/serial_core.c:618
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:1017 [inline]
file_tty_write.constprop.0+0x519/0x9b0 drivers/tty/tty_io.c:1088
tty_write drivers/tty/tty_io.c:1109 [inline]
redirected_tty_write drivers/tty/tty_io.c:1132 [inline]
redirected_tty_write+0xa6/0xc0 drivers/tty/tty_io.c:1112
call_write_iter include/linux/fs.h:1966 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x64f/0xe40 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+0x38/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #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:3410
console_emit_next_record kernel/printk/printk.c:2894 [inline]
console_flush_all+0x4d5/0xd50 kernel/printk/printk.c:2960
console_unlock+0x10c/0x260 kernel/printk/printk.c:3029
vprintk_emit+0x17f/0x5f0 kernel/printk/printk.c:2304
vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45
_printk+0xc8/0x100 kernel/printk/printk.c:2329
register_console+0xb30/0x1210 kernel/printk/printk.c:3535
univ8250_console_init+0x35/0x50 drivers/tty/serial/8250/8250_core.c:717
console_init+0xba/0x5c0 kernel/printk/printk.c:3681
start_kernel+0x25a/0x480 init/main.c:1004
x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:556
x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:537
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:3868 [inline]
__lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
console_trylock_spinning kernel/printk/printk.c:1963 [inline]
vprintk_emit+0x328/0x5f0 kernel/printk/printk.c:2303
vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45
_printk+0xc8/0x100 kernel/printk/printk.c:2329
pick_eevdf kernel/sched/fair.c:963 [inline]
pick_next_entity kernel/sched/fair.c:5247 [inline]
pick_next_task_fair+0x1c5/0x1280 kernel/sched/fair.c:8205
__pick_next_task kernel/sched/core.c:5986 [inline]
pick_next_task kernel/sched/core.c:6061 [inline]
__schedule+0x493/0x5a00 kernel/sched/core.c:6640
__schedule_loop kernel/sched/core.c:6753 [inline]
schedule+0xe7/0x270 kernel/sched/core.c:6768
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6825
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x969/0x1340 kernel/locking/mutex.c:747
ieee80211_register_hw+0x26d0/0x4260 net/mac80211/main.c:1408
mac80211_hwsim_new_radio+0x24cf/0x4cb0 drivers/net/wireless/virtual/mac80211_hwsim.c:5304
hwsim_new_radio_nl+0xaf8/0x1240 drivers/net/wireless/virtual/mac80211_hwsim.c:5985
genl_family_rcv_msg_doit+0x1fc/0x2e0 net/netlink/genetlink.c:971
genl_family_rcv_msg net/netlink/genetlink.c:1051 [inline]
genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1066
netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2545
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1075
netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline]
netlink_unicast+0x536/0x810 net/netlink/af_netlink.c:1368
netlink_sendmsg+0x93c/0xe40 net/netlink/af_netlink.c:1910
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0xd5/0x180 net/socket.c:745
__sys_sendto+0x255/0x340 net/socket.c:2194
__do_sys_sendto net/socket.c:2206 [inline]
__se_sys_sendto net/socket.c:2202 [inline]
__x64_sys_sendto+0xe0/0x1b0 net/socket.c:2202
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x63/0xcd

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 ***

4 locks held by syz-executor.4/5092:
#0: ffffffff8e6a8450 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1074
#1: ffffffff8e6a8508 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffffffff8e6a8508 (genl_mutex){+.+.}-{3:3}, at: genl_op_lock net/netlink/genetlink.c:58 [inline]
#1: ffffffff8e6a8508 (genl_mutex){+.+.}-{3:3}, at: genl_op_lock net/netlink/genetlink.c:55 [inline]
#1: ffffffff8e6a8508 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x577/0x800 net/netlink/genetlink.c:1065
#2: ffffffff8e60db28 (rtnl_mutex){+.+.}-{3:3}, at: ieee80211_register_hw+0x26d0/0x4260 net/mac80211/main.c:1408
#3: ffff8880b993c718 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:558

stack backtrace:
CPU: 1 PID: 5092 Comm: syz-executor.4 Not tainted 6.6.0-rc4-next-20231005-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
check_noncircular+0x311/0x3f0 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:3868 [inline]
__lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
console_trylock_spinning kernel/printk/printk.c:1963 [inline]
vprintk_emit+0x328/0x5f0 kernel/printk/printk.c:2303
vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45
_printk+0xc8/0x100 kernel/printk/printk.c:2329
pick_eevdf kernel/sched/fair.c:963 [inline]
pick_next_entity kernel/sched/fair.c:5247 [inline]
pick_next_task_fair+0x1c5/0x1280 kernel/sched/fair.c:8205
__pick_next_task kernel/sched/core.c:5986 [inline]
pick_next_task kernel/sched/core.c:6061 [inline]
__schedule+0x493/0x5a00 kernel/sched/core.c:6640
__schedule_loop kernel/sched/core.c:6753 [inline]
schedule+0xe7/0x270 kernel/sched/core.c:6768
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6825
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x969/0x1340 kernel/locking/mutex.c:747
ieee80211_register_hw+0x26d0/0x4260 net/mac80211/main.c:1408
mac80211_hwsim_new_radio+0x24cf/0x4cb0 drivers/net/wireless/virtual/mac80211_hwsim.c:5304
hwsim_new_radio_nl+0xaf8/0x1240 drivers/net/wireless/virtual/mac80211_hwsim.c:5985
genl_family_rcv_msg_doit+0x1fc/0x2e0 net/netlink/genetlink.c:971
genl_family_rcv_msg net/netlink/genetlink.c:1051 [inline]
genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1066
netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2545
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1075
netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline]
netlink_unicast+0x536/0x810 net/netlink/af_netlink.c:1368
netlink_sendmsg+0x93c/0xe40 net/netlink/af_netlink.c:1910
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0xd5/0x180 net/socket.c:745
__sys_sendto+0x255/0x340 net/socket.c:2194
__do_sys_sendto net/socket.c:2206 [inline]
__se_sys_sendto net/socket.c:2202 [inline]
__x64_sys_sendto+0xe0/0x1b0 net/socket.c:2202
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6ec907e7dc
Code: 1a 51 02 00 44 8b 4c 24 2c 4c 8b 44 24 20 89 c5 44 8b 54 24 28 48 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 <48> 3d 00 f0 ff ff 77 34 89 ef 48 89 44 24 08 e8 60 51 02 00 48 8b
RSP: 002b:00007fff330e2f40 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f6ec9cc4620 RCX: 00007f6ec907e7dc
RDX: 0000000000000024 RSI: 00007f6ec9cc4670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007fff330e2f94 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f6ec9cc4670 R15: 0000000000000000
</TASK>
ieee80211 phy14: Selected rate control algorithm 'minstrel_ht'

---
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Next message: Naresh Kamboju: "Kunit: BUG: KASAN: null-ptr-deref in __fpga_bridge_get+0x88/0x100 [fpga_bridge]"
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