syzbot
inconsistent lock state in fs_reclaim_acquire (4)
Status:
upstream: reported C repro on 2026/09/09 22:45
Subsystems:
mm
cgroups
Labels:
prio:high
[Documentation on labels]
Reported-by: syzbot+093e05755c2d99caab91@syzkaller.appspotmail.com
First crash: 23h42m, last: 18h33m
Sample crash report:
================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
syz.3.17/3981 [HC0[0]:SC1[1]:HE0:SE0] takes:
ffffffff89ab7bc0 (fs_reclaim){+.?.}-{0:0}, at: might_alloc include/linux/sched/mm.h:316 [inline]
ffffffff89ab7bc0 (fs_reclaim){+.?.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4636 [inline]
ffffffff89ab7bc0 (fs_reclaim){+.?.}-{0:0}, at: slab_alloc_node mm/slub.c:4974 [inline]
ffffffff89ab7bc0 (fs_reclaim){+.?.}-{0:0}, at: __do_kmalloc_node mm/slub.c:5413 [inline]
ffffffff89ab7bc0 (fs_reclaim){+.?.}-{0:0}, at: __kmalloc_node_track_caller_noprof+0xcc/0x820 mm/slub.c:5545
{SOFTIRQ-ON-W} state was registered at:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
__fs_reclaim_acquire mm/page_alloc.c:4375 [inline]
fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4389
might_alloc include/linux/sched/mm.h:316 [inline]
xa_alloc include/linux/xarray.h:876 [inline]
mem_cgroup_alloc mm/memcontrol.c:4160 [inline]
mem_cgroup_css_alloc+0x7e/0x1ce0 mm/memcontrol.c:4225
cgroup_init_subsys+0x223/0x700 kernel/cgroup/cgroup.c:6431
cgroup_init+0x569/0xe50 kernel/cgroup/cgroup.c:6558
start_kernel+0x470/0x490 init/main.c:1176
x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
x86_64_start_kernel+0x12b/0x130 arch/x86/kernel/head64.c:291
common_startup_64+0x13e/0x158
irq event stamp: 317
hardirqs last enabled at (316): [<ffffffff878ad162>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:210 [inline]
hardirqs last enabled at (316): [<ffffffff878ad162>] _raw_spin_unlock_irqrestore+0x52/0x80 kernel/locking/spinlock.c:221
hardirqs last disabled at (317): [<ffffffff878acd32>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:153 [inline]
hardirqs last disabled at (317): [<ffffffff878acd32>] _raw_spin_lock_irqsave+0x52/0x60 kernel/locking/spinlock.c:181
softirqs last enabled at (302): [<ffffffff8177a2a8>] __do_softirq kernel/softirq.c:679 [inline]
softirqs last enabled at (302): [<ffffffff8177a2a8>] invoke_softirq kernel/softirq.c:519 [inline]
softirqs last enabled at (302): [<ffffffff8177a2a8>] __irq_exit_rcu+0x168/0x210 kernel/softirq.c:758
softirqs last disabled at (313): [<ffffffff8177a2a8>] __do_softirq kernel/softirq.c:679 [inline]
softirqs last disabled at (313): [<ffffffff8177a2a8>] invoke_softirq kernel/softirq.c:519 [inline]
softirqs last disabled at (313): [<ffffffff8177a2a8>] __irq_exit_rcu+0x168/0x210 kernel/softirq.c:758
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(fs_reclaim);
<Interrupt>
lock(fs_reclaim);
*** DEADLOCK ***
locks held by syz.3.17/3981: 1, on CPU#0:
#0: ffff888122130870 (&hiddev->existancelock){+.+.}-{4:4}, at: hiddev_ioctl+0x165/0x15b0 drivers/hid/usbhid/hiddev.c:610
stack backtrace:
CPU: 0 UID: 0 PID: 3981 Comm: syz.3.17 Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_usage_bug.part.0+0x258/0x340 kernel/locking/lockdep.c:4086
print_usage_bug kernel/locking/lockdep.c:4054 [inline]
valid_state kernel/locking/lockdep.c:4100 [inline]
mark_lock_irq kernel/locking/lockdep.c:4311 [inline]
mark_lock+0x956/0x1020 kernel/locking/lockdep.c:4797
mark_usage kernel/locking/lockdep.c:4686 [inline]
__lock_acquire+0x7f1/0x1f40 kernel/locking/lockdep.c:5242
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
__fs_reclaim_acquire mm/page_alloc.c:4375 [inline]
fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4389
might_alloc include/linux/sched/mm.h:316 [inline]
slab_pre_alloc_hook mm/slub.c:4636 [inline]
slab_alloc_node mm/slub.c:4974 [inline]
__do_kmalloc_node mm/slub.c:5413 [inline]
__kmalloc_node_track_caller_noprof+0xcc/0x820 mm/slub.c:5545
alloc_dr drivers/base/devres.c:141 [inline]
devm_kmalloc+0xa5/0x2b0 drivers/base/devres.c:951
devm_kzalloc include/linux/device/devres.h:50 [inline]
mt_allocate_report_data+0x59/0xcc0 drivers/hid/hid-multitouch.c:695
mt_find_report_data drivers/hid/hid-multitouch.c:745 [inline]
mt_event+0x1bf/0x270 drivers/hid/hid-multitouch.c:1570
hid_process_event+0x37d/0x5a0 drivers/hid/hid-core.c:1572
hid_process_report drivers/hid/hid-core.c:1730 [inline]
hid_report_raw_event+0xb14/0x14c0 drivers/hid/hid-core.c:2109
__hid_input_report.constprop.0+0x349/0x470 drivers/hid/hid-core.c:2180
hid_ctrl+0x4a4/0x560 drivers/hid/usbhid/hid-core.c:486
__usb_hcd_giveback_urb+0x38e/0x610 drivers/usb/core/hcd.c:1657
usb_hcd_giveback_urb+0x3ca/0x4a0 drivers/usb/core/hcd.c:1741
dummy_timer+0xdb2/0x3700 drivers/usb/gadget/udc/dummy_hcd.c:2019
__run_hrtimer kernel/time/hrtimer.c:2067 [inline]
__hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2124
hrtimer_run_softirq+0x1ca/0x360 kernel/time/hrtimer.c:2141
handle_softirqs+0x1d9/0x9b0 kernel/softirq.c:645
__do_softirq kernel/softirq.c:679 [inline]
invoke_softirq kernel/softirq.c:519 [inline]
__irq_exit_rcu+0x168/0x210 kernel/softirq.c:758
irq_exit_rcu+0x9/0x30 kernel/softirq.c:775
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0x8f/0xb0 arch/x86/kernel/apic/apic.c:1062
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:211 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:221
Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 56 f7 05 fa 48 89 df e8 de 4d 06 fa f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 <bf> 01 00 00 00 e8 65 a3 f8 f9 65 48 83 3d d4 ee 98 05 00 74 16 5b
RSP: 0018:ffffc90001bff9f0 EFLAGS: 00000246
RAX: 0000000000000002 RBX: ffff8881f5625fc0 RCX: 0000000000000040
RDX: 0000000000000001 RSI: ffffffff89329b79 RDI: ffffffff87d2b780
RBP: 0000000000000287 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8881f5625fc0
R13: 0000000000000000 R14: 00000000ffffffff R15: ffff8881f5626008
__mod_timer+0x409/0xca0 kernel/time/timer.c:1139
add_timer+0x62/0x90 kernel/time/timer.c:1249
schedule_timeout+0x122/0x280 kernel/time/sleep_timeout.c:98
usbhid_wait_io+0x24e/0x420 drivers/hid/usbhid/hid-core.c:648
usbhid_init_reports+0x1a7/0x390 drivers/hid/usbhid/hid-core.c:787
hiddev_ioctl+0xddb/0x15b0 drivers/hid/usbhid/hiddev.c:794
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x119/0x710 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f01bd5ee159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f01bd42e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f01bd876090 RCX: 00007f01bd5ee159
RDX: 0000000000000000 RSI: 00000000c018480b RDI: 0000000000000004
RBP: 00007f01bd68503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f01bd876128 R14: 00007f01bd876090 R15: 00007ffe3b7b3048
</TASK>
------------[ cut here ]------------
do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff818d66ad>] prepare_to_wait_event+0x8d/0x720 kernel/sched/wait.c:318
WARNING: kernel/sched/core.c:9179 at __might_sleep+0x94/0xc0 kernel/sched/core.c:9179, CPU#0: syz.3.17/3981
Modules linked in:
CPU: 0 UID: 0 PID: 3981 Comm: syz.3.17 Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__might_sleep+0x97/0xc0 kernel/sched/core.c:9179
Code: 8b 94 24 c0 17 00 00 48 85 d2 75 14 48 83 c4 08 89 ee 48 89 df 31 d2 5b 5d 41 5c e9 33 fc ff ff 48 8d 3d 5c d9 92 09 48 89 d1 <67> 48 0f b9 3a eb db e8 fd 20 9c 00 eb 9f 89 74 24 04 e8 22 21 9c
RSP: 0018:ffffc90000007828 EFLAGS: 00010082
RAX: dffffc0000000000 RBX: ffffffff8931ad45 RCX: ffffffff818d66ad
RDX: ffffffff818d66ad RSI: 0000000000000002 RDI: ffffffff8b16a1e0
RBP: 0000000000000142 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff888107ed3c80
R13: 0000000000000dc0 R14: 00000000ffffffff R15: 00000000ffffffff
FS: 00007f01bd42e6c0(0000) GS:ffff8882683e4000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f01bd42dff8 CR3: 00000001214ba000 CR4: 00000000003506f0
Call Trace:
<IRQ>
might_alloc include/linux/sched/mm.h:322 [inline]
slab_pre_alloc_hook mm/slub.c:4636 [inline]
slab_alloc_node mm/slub.c:4974 [inline]
__do_kmalloc_node mm/slub.c:5413 [inline]
__kmalloc_node_track_caller_noprof+0x473/0x820 mm/slub.c:5545
alloc_dr drivers/base/devres.c:141 [inline]
devm_kmalloc+0xa5/0x2b0 drivers/base/devres.c:951
devm_kzalloc include/linux/device/devres.h:50 [inline]
mt_allocate_report_data+0x59/0xcc0 drivers/hid/hid-multitouch.c:695
mt_find_report_data drivers/hid/hid-multitouch.c:745 [inline]
mt_event+0x1bf/0x270 drivers/hid/hid-multitouch.c:1570
hid_process_event+0x37d/0x5a0 drivers/hid/hid-core.c:1572
hid_process_report drivers/hid/hid-core.c:1730 [inline]
hid_report_raw_event+0xb14/0x14c0 drivers/hid/hid-core.c:2109
__hid_input_report.constprop.0+0x349/0x470 drivers/hid/hid-core.c:2180
hid_ctrl+0x4a4/0x560 drivers/hid/usbhid/hid-core.c:486
__usb_hcd_giveback_urb+0x38e/0x610 drivers/usb/core/hcd.c:1657
usb_hcd_giveback_urb+0x3ca/0x4a0 drivers/usb/core/hcd.c:1741
dummy_timer+0xdb2/0x3700 drivers/usb/gadget/udc/dummy_hcd.c:2019
__run_hrtimer kernel/time/hrtimer.c:2067 [inline]
__hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2124
hrtimer_run_softirq+0x1ca/0x360 kernel/time/hrtimer.c:2141
handle_softirqs+0x1d9/0x9b0 kernel/softirq.c:645
__do_softirq kernel/softirq.c:679 [inline]
invoke_softirq kernel/softirq.c:519 [inline]
__irq_exit_rcu+0x168/0x210 kernel/softirq.c:758
irq_exit_rcu+0x9/0x30 kernel/softirq.c:775
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0x8f/0xb0 arch/x86/kernel/apic/apic.c:1062
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:211 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:221
Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 56 f7 05 fa 48 89 df e8 de 4d 06 fa f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 <bf> 01 00 00 00 e8 65 a3 f8 f9 65 48 83 3d d4 ee 98 05 00 74 16 5b
RSP: 0018:ffffc90001bff9f0 EFLAGS: 00000246
RAX: 0000000000000002 RBX: ffff8881f5625fc0 RCX: 0000000000000040
RDX: 0000000000000001 RSI: ffffffff89329b79 RDI: ffffffff87d2b780
RBP: 0000000000000287 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8881f5625fc0
R13: 0000000000000000 R14: 00000000ffffffff R15: ffff8881f5626008
__mod_timer+0x409/0xca0 kernel/time/timer.c:1139
add_timer+0x62/0x90 kernel/time/timer.c:1249
schedule_timeout+0x122/0x280 kernel/time/sleep_timeout.c:98
usbhid_wait_io+0x24e/0x420 drivers/hid/usbhid/hid-core.c:648
usbhid_init_reports+0x1a7/0x390 drivers/hid/usbhid/hid-core.c:787
hiddev_ioctl+0xddb/0x15b0 drivers/hid/usbhid/hiddev.c:794
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x119/0x710 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f01bd5ee159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f01bd42e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f01bd876090 RCX: 00007f01bd5ee159
RDX: 0000000000000000 RSI: 00000000c018480b RDI: 0000000000000004
RBP: 00007f01bd68503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f01bd876128 R14: 00007f01bd876090 R15: 00007ffe3b7b3048
</TASK>
----------------
Code disassembly (best guess):
0: f5 cmc
1: 53 push %rbx
2: 48 8b 74 24 10 mov 0x10(%rsp),%rsi
7: 48 89 fb mov %rdi,%rbx
a: 48 83 c7 18 add $0x18,%rdi
e: e8 56 f7 05 fa call 0xfa05f769
13: 48 89 df mov %rbx,%rdi
16: e8 de 4d 06 fa call 0xfa064df9
1b: f7 c5 00 02 00 00 test $0x200,%ebp
21: 75 23 jne 0x46
23: 9c pushf
24: 58 pop %rax
25: f6 c4 02 test $0x2,%ah
28: 75 37 jne 0x61
* 2a: bf 01 00 00 00 mov $0x1,%edi <-- trapping instruction
2f: e8 65 a3 f8 f9 call 0xf9f8a399
34: 65 48 83 3d d4 ee 98 cmpq $0x0,%gs:0x598eed4(%rip) # 0x598ef11
3b: 05 00
3d: 74 16 je 0x55
3f: 5b pop %rbx
Struck through repros no longer work on HEAD.