[PATCH] kernel/evdev: suppress irq bad dependency lockdep report
From: Wojciech Gładysz
Date: Thu Aug 01 2024 - 05:28:28 EST
Lockdep connects soft irq (keyboard tasklet injecting led events)
and vfs started (lease break) locking chains. In the test scenario
the chains do not connect due to event type/code and client->fasync.
commit 45a3e24f65e9 ("Linux 6.4-rc7")
Backtrace
=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
5.10.0-syzkaller #0 Not tainted
-----------------------------------------------------
syz-executor175/2640 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffffffff8720b458 (tasklist_lock){.+.+}-{2:2}, at: send_sigio+0xdc/0x340
and this task is already holding:
ffff88800bc0e978 (&f->f_owner.lock){....}-{2:2}, at: send_sigio+0x31/0x340
which would create a new lock dependency:
(&f->f_owner.lock){....}-{2:2} -> (tasklist_lock){.+.+}-{2:2}
but this new dependency connects a SOFTIRQ-irq-safe lock:
(&client->buffer_lock){..-.}-{2:2}
... which became SOFTIRQ-irq-safe at:
lock_acquire+0x197/0x480
_raw_spin_lock+0x2a/0x40
evdev_pass_values+0xef/0xaf0
evdev_events+0x1ba/0x2f0
input_pass_values+0x87e/0x1200
input_handle_event+0xc17/0x1500
input_inject_event+0x1eb/0x2f0
kbd_update_leds_helper+0xfd/0x130
input_handler_for_each_handle+0xdc/0x1a0
kbd_bh+0x180/0x250
tasklet_action_common+0x2e1/0x3d0
tasklet_action+0x1d/0x20
__do_softirq+0x3e6/0x94e
run_ksoftirqd+0x96/0xf0
smpboot_thread_fn+0x557/0x900
kthread+0x374/0x3f0
ret_from_fork+0x3a/0x50
to a SOFTIRQ-irq-unsafe lock:
(tasklist_lock){.+.+}-{2:2}
... which became SOFTIRQ-irq-unsafe at:
...
lock_acquire+0x197/0x480
_raw_read_lock+0x32/0x50
do_wait+0x356/0xc80
kernel_wait+0xe5/0x240
call_usermodehelper_exec_work+0xb7/0x220
process_one_work+0x857/0xfd0
worker_thread+0xafa/0x1550
kthread+0x374/0x3f0
ret_from_fork+0x3a/0x50
other info that might help us debug this:
Chain exists of:
&client->buffer_lock --> &f->f_owner.lock --> tasklist_lock
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(tasklist_lock);
local_irq_disable();
lock(&client->buffer_lock);
lock(&f->f_owner.lock);
<Interrupt>
lock(&client->buffer_lock);
*** DEADLOCK ***
5 locks held by syz-executor175/2640:
#0: ffffffff879b7bf0 (file_rwsem){.+.+}-{0:0}, at: __break_lease+0x186/0x1300
#1: ffff88800f2d2dd8 (&ctx->flc_lock){+.+.}-{2:2}, at: __break_lease+0x193/0x1300
#2: ffffffff8784ba80 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x40
#3: ffff88800ea3d9f0 (&new->fa_lock){....}-{2:2}, at: kill_fasync+0x15f/0x480
#4: ffff88800bc0e978 (&f->f_owner.lock){....}-{2:2}, at: send_sigio+0x31/0x340
the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (&client->buffer_lock){..-.}-{2:2} {
IN-SOFTIRQ-W at:
lock_acquire+0x197/0x480
_raw_spin_lock+0x2a/0x40
evdev_pass_values+0xef/0xaf0
evdev_events+0x1ba/0x2f0
input_pass_values+0x87e/0x1200
input_handle_event+0xc17/0x1500
input_inject_event+0x1eb/0x2f0
kbd_update_leds_helper+0xfd/0x130
input_handler_for_each_handle+0xdc/0x1a0
kbd_bh+0x180/0x250
tasklet_action_common+0x2e1/0x3d0
tasklet_action+0x1d/0x20
__do_softirq+0x3e6/0x94e
run_ksoftirqd+0x96/0xf0
smpboot_thread_fn+0x557/0x900
kthread+0x374/0x3f0
ret_from_fork+0x3a/0x50
INITIAL USE at:
lock_acquire+0x197/0x480
_raw_spin_lock+0x2a/0x40
evdev_pass_values+0xef/0xaf0
evdev_events+0x1ba/0x2f0
input_pass_values+0x87e/0x1200
input_handle_event+0xc17/0x1500
input_inject_event+0x1eb/0x2f0
evdev_write+0x37b/0x580
vfs_write+0x287/0xc90
ksys_write+0x17e/0x2a0
__x64_sys_write+0x7b/0x90
do_syscall_64+0x4f/0x60
entry_SYSCALL_64_after_hwframe+0x61/0xc6
}
... key at: [<ffffffff895f5640>] evdev_open.__key.17+0x0/0x20
-> (&new->fa_lock){....}-{2:2} {
INITIAL READ USE at:
lock_acquire+0x197/0x480
_raw_read_lock_irqsave+0xb8/0x100
kill_fasync+0x15f/0x480
evdev_pass_values+0x5b9/0xaf0
evdev_events+0x1ba/0x2f0
input_pass_values+0x87e/0x1200
input_handle_event+0xc17/0x1500
input_inject_event+0x1eb/0x2f0
evdev_write+0x37b/0x580
vfs_write+0x287/0xc90
ksys_write+0x17e/0x2a0
__x64_sys_write+0x7b/0x90
do_syscall_64+0x4f/0x60
entry_SYSCALL_64_after_hwframe+0x61/0xc6
}
... key at: [<ffffffff8943f5e0>] fasync_insert_entry.__key+0x0/0x20
... acquired at:
lock_acquire+0x197/0x480
_raw_read_lock_irqsave+0xb8/0x100
kill_fasync+0x15f/0x480
evdev_pass_values+0x5b9/0xaf0
evdev_events+0x1ba/0x2f0
input_pass_values+0x87e/0x1200
input_handle_event+0xc17/0x1500
input_inject_event+0x1eb/0x2f0
evdev_write+0x37b/0x580
vfs_write+0x287/0xc90
ksys_write+0x17e/0x2a0
__x64_sys_write+0x7b/0x90
do_syscall_64+0x4f/0x60
entry_SYSCALL_64_after_hwframe+0x61/0xc6
-> (&f->f_owner.lock){....}-{2:2} {
INITIAL USE at:
lock_acquire+0x197/0x480
_raw_write_lock_irq+0xab/0xf0
f_modown+0x3b/0x350
do_fcntl+0x139b/0x1750
__se_sys_fcntl+0xe3/0x1c0
__x64_sys_fcntl+0x7b/0x90
do_syscall_64+0x4f/0x60
entry_SYSCALL_64_after_hwframe+0x61/0xc6
INITIAL READ USE at:
lock_acquire+0x197/0x480
_raw_read_lock_irqsave+0xb8/0x100
send_sigio+0x31/0x340
kill_fasync+0x1fb/0x480
evdev_pass_values+0x5b9/0xaf0
evdev_events+0x1ba/0x2f0
input_pass_values+0x87e/0x1200
input_handle_event+0xc17/0x1500
input_inject_event+0x1eb/0x2f0
evdev_write+0x37b/0x580
vfs_write+0x287/0xc90
ksys_write+0x17e/0x2a0
__x64_sys_write+0x7b/0x90
do_syscall_64+0x4f/0x60
entry_SYSCALL_64_after_hwframe+0x61/0xc6
}
... key at: [<ffffffff8943e960>] __alloc_file.__key+0x0/0x10
... acquired at:
lock_acquire+0x197/0x480
_raw_read_lock_irqsave+0xb8/0x100
send_sigio+0x31/0x340
kill_fasync+0x1fb/0x480
evdev_pass_values+0x5b9/0xaf0
evdev_events+0x1ba/0x2f0
input_pass_values+0x87e/0x1200
input_handle_event+0xc17/0x1500
input_inject_event+0x1eb/0x2f0
evdev_write+0x37b/0x580
vfs_write+0x287/0xc90
ksys_write+0x17e/0x2a0
__x64_sys_write+0x7b/0x90
do_syscall_64+0x4f/0x60
entry_SYSCALL_64_after_hwframe+0x61/0xc6
the dependencies between the lock to be acquired
and SOFTIRQ-irq-unsafe lock:
-> (tasklist_lock){.+.+}-{2:2} {
HARDIRQ-ON-R at:
lock_acquire+0x197/0x480
_raw_read_lock+0x32/0x50
do_wait+0x356/0xc80
kernel_wait+0xe5/0x240
call_usermodehelper_exec_work+0xb7/0x220
process_one_work+0x857/0xfd0
worker_thread+0xafa/0x1550
kthread+0x374/0x3f0
ret_from_fork+0x3a/0x50
SOFTIRQ-ON-R at:
lock_acquire+0x197/0x480
_raw_read_lock+0x32/0x50
do_wait+0x356/0xc80
kernel_wait+0xe5/0x240
call_usermodehelper_exec_work+0xb7/0x220
process_one_work+0x857/0xfd0
worker_thread+0xafa/0x1550
kthread+0x374/0x3f0
ret_from_fork+0x3a/0x50
INITIAL USE at:
lock_acquire+0x197/0x480
_raw_write_lock_irq+0xab/0xf0
copy_process+0x2192/0x3880
kernel_clone+0x220/0x7a0
kernel_thread+0x147/0x1c0
rest_init+0x24/0x300
arch_call_rest_init+0xe/0x11
start_kernel+0x469/0x512
x86_64_start_reservations+0x2a/0x2d
x86_64_start_kernel+0x60/0x64
secondary_startup_64_no_verify+0xac/0xbb
INITIAL READ USE at:
lock_acquire+0x197/0x480
_raw_read_lock+0x32/0x50
do_wait+0x356/0xc80
kernel_wait+0xe5/0x240
call_usermodehelper_exec_work+0xb7/0x220
process_one_work+0x857/0xfd0
worker_thread+0xafa/0x1550
kthread+0x374/0x3f0
ret_from_fork+0x3a/0x50
}
... key at: [<ffffffff8720b458>] tasklist_lock+0x18/0x40
... acquired at:
lock_acquire+0x197/0x480
_raw_read_lock+0x32/0x50
send_sigio+0xdc/0x340
kill_fasync+0x1fb/0x480
lease_break_callback+0x26/0x30
__break_lease+0x4d1/0x1300
do_dentry_open+0x6ac/0xf40
vfs_open+0x73/0x80
path_openat+0x26c5/0x3290
do_filp_open+0x20b/0x450
do_sys_openat2+0x124/0x460
__x64_sys_open+0x221/0x270
do_syscall_64+0x4f/0x60
entry_SYSCALL_64_after_hwframe+0x61/0xc6
stack backtrace:
CPU: 2 PID: 2640 Comm: syz-executor175 Not tainted 5.10.0-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
dump_stack+0x183/0x226
validate_chain+0x4cca/0x5870
__lock_acquire+0x12fd/0x20d0
lock_acquire+0x197/0x480
_raw_read_lock+0x32/0x50
send_sigio+0xdc/0x340
kill_fasync+0x1fb/0x480
lease_break_callback+0x26/0x30
__break_lease+0x4d1/0x1300
do_dentry_open+0x6ac/0xf40
vfs_open+0x73/0x80
path_openat+0x26c5/0x3290
do_filp_open+0x20b/0x450
do_sys_openat2+0x124/0x460
__x64_sys_open+0x221/0x270
do_syscall_64+0x4f/0x60
entry_SYSCALL_64_after_hwframe+0x61/0xc6
RIP: 0033:0x7f65eb366509
Code: 28 c3 e8 1a 15 00 00 66 2e 0f 1f 84 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffac3b94b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f65eb3d3ed0 RCX: 00007f65eb366509
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000020000240
RBP: 00007fffac3b94c8 R08: 00007f65eb3d3e40 R09: 00007f65eb3d3e40
R10: 00007f65eb3d3e40 R11: 0000000000000246 R12: 00007fffac3b94d0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Signed-off-by: Wojciech Gładysz <wojciech.gladysz@xxxxxxxxxxxx>
---
drivers/input/evdev.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index a8ce3d140722..e579e5b98757 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -257,8 +257,13 @@ static void evdev_pass_values(struct evdev_client *client,
event.input_event_sec = ts.tv_sec;
event.input_event_usec = ts.tv_nsec / NSEC_PER_USEC;
- /* Interrupts are disabled, just acquire the lock. */
- spin_lock(&client->buffer_lock);
+ /*
+ * Disable lockdep chain connecting with subclass based on fasync
+ * to suppress lockdep report. No further locking for NULL fasync
+ * (keybord_tasklet injecting input events).
+ * Interrupts are disabled, just acquire the lock.
+ */
+ spin_lock_nested(&client->buffer_lock, !client->fasync);
for (v = vals; v != vals + count; v++) {
if (__evdev_is_filtered(client, v->type, v->code))
--
2.35.3