[v6.1] INFO: rcu detected stall in sys_rt_sigreturn
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syzbot
Sep 16, 2025, 8:37:36 AM9/16/25
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 3db754f56897 Linux 6.1.152
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11b73762580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7eb38bd5021fec61
dashboard link: https://syzkaller.appspot.com/bug?extid=b0c669c304df2c205c64
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/662de00db314/disk-3db754f5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/74288f70f46c/vmlinux-3db754f5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ab4512d1fabb/bzImage-3db754f5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0c669...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6421/1:b..l
(detected by 0, t=10502 jiffies, g=28753, q=41 ncpus=2)
task:syz.7.357 state:R running task stack:26464 pid:6421 ppid:5928 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6730
preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6754
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0xf6/0x100 kernel/locking/spinlock.c:194
bpf_lru_pop_free+0x19a5/0x1c60 include/linux/list.h:-1
prealloc_lru_pop kernel/bpf/hashtab.c:296 [inline]
__htab_lru_percpu_map_update_elem+0x1ff/0x8c0 kernel/bpf/hashtab.c:1333
bpf_percpu_hash_update+0x115/0x200 kernel/bpf/hashtab.c:2336
bpf_map_update_value+0x310/0x670 kernel/bpf/syscall.c:202
generic_map_update_batch+0x569/0x850 kernel/bpf/syscall.c:1709
bpf_map_do_batch+0x466/0x600 kernel/bpf/syscall.c:-1
__sys_bpf+0x65f/0x6d0 kernel/bpf/syscall.c:-1
__do_sys_bpf kernel/bpf/syscall.c:5131 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5129 [inline]
__x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5129
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9f10d8eba9
RSP: 002b:00007f9f11c8f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f9f10fd6090 RCX: 00007f9f10d8eba9
RDX: 0000000000000038 RSI: 0000200000000780 RDI: 000000000000001a
RBP: 00007f9f10e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9f10fd6128 R14: 00007f9f10fd6090 R15: 00007ffdaedbc198
</TASK>
rcu: rcu_preempt kthread starved for 10510 jiffies! g28753 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:27200 pid:16 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
schedule+0xb9/0x180 kernel/sched/core.c:6637
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7098 Comm: syz.0.483 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:207 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:147 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:254 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:206
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 89 f6 31 d2 e9 ef c7 f7 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc900001e0e38 EFLAGS: 00000046
RAX: 00000000000048bf RBX: 00000000000048bf RCX: 0000000000000838
RDX: 0000000000000000 RSI: 00000000000048bf RDI: 0000000000000838
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffffbfff1c3eea6
R10: fffffbfff1c3eea6 R11: 1ffffffff1c3eea5 R12: dffffc0000000000
R13: 0000000010005df3 R14: ffffffff8c5e4b40 R15: dffffc0000000000
FS: 00007feceef486c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000f7d000 CR3: 000000002e8d8000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
apic_write arch/x86/include/asm/apic.h:394 [inline]
lapic_next_event+0x5b/0x70 arch/x86/kernel/apic/apic.c:478
clockevents_program_event+0x1bc/0x310 kernel/time/clockevents.c:334
hrtimer_interrupt+0x59d/0x9c0 kernel/time/hrtimer.c:1891
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc9001fd7f9e0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 5b5a7f4a0918e200
RDX: 0000000000000000 RSI: ffffffff8a8c1680 RDI: ffffffff8adefca0
RBP: ffffc9001fd7faf0 R08: dffffc0000000000 R09: fffffbfff215c44f
R10: fffffbfff215c44f R11: 1ffffffff215c44e R12: 0000000000000001
R13: 1ffff92003faff48 R14: 0000000000000246 R15: dffffc0000000000
__might_fault+0xc2/0x120 mm/memory.c:5852
__copy_from_user include/linux/uaccess.h:75 [inline]
check_xstate_in_sigframe arch/x86/kernel/fpu/signal.c:35 [inline]
__fpu_restore_sig arch/x86/kernel/fpu/signal.c:348 [inline]
fpu__restore_sig+0x203/0x1190 arch/x86/kernel/fpu/signal.c:493
restore_sigcontext arch/x86/kernel/signal.c:140 [inline]
__ia32_sys_rt_sigreturn+0x649/0x790 arch/x86/kernel/signal.c:675
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fecee18eba7
Code: ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89
RSP: 002b:00007feceef48038 EFLAGS: 00000246
RAX: 000000000000002f RBX: 00007fecee3d5fa0 RCX: 00007fecee18eba9
RDX: 0000000000002020 RSI: 0000200000000480 RDI: 0000000000000008
RBP: 00007fecee211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fecee3d6038 R14: 00007fecee3d5fa0 R15: 00007fffefc856e8
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 3db754f56897 Linux 6.1.152
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11b73762580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7eb38bd5021fec61
dashboard link: https://syzkaller.appspot.com/bug?extid=b0c669c304df2c205c64
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/662de00db314/disk-3db754f5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/74288f70f46c/vmlinux-3db754f5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ab4512d1fabb/bzImage-3db754f5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0c669...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6421/1:b..l
(detected by 0, t=10502 jiffies, g=28753, q=41 ncpus=2)
task:syz.7.357 state:R running task stack:26464 pid:6421 ppid:5928 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6730
preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6754
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0xf6/0x100 kernel/locking/spinlock.c:194
bpf_lru_pop_free+0x19a5/0x1c60 include/linux/list.h:-1
prealloc_lru_pop kernel/bpf/hashtab.c:296 [inline]
__htab_lru_percpu_map_update_elem+0x1ff/0x8c0 kernel/bpf/hashtab.c:1333
bpf_percpu_hash_update+0x115/0x200 kernel/bpf/hashtab.c:2336
bpf_map_update_value+0x310/0x670 kernel/bpf/syscall.c:202
generic_map_update_batch+0x569/0x850 kernel/bpf/syscall.c:1709
bpf_map_do_batch+0x466/0x600 kernel/bpf/syscall.c:-1
__sys_bpf+0x65f/0x6d0 kernel/bpf/syscall.c:-1
__do_sys_bpf kernel/bpf/syscall.c:5131 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5129 [inline]
__x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5129
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9f10d8eba9
RSP: 002b:00007f9f11c8f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f9f10fd6090 RCX: 00007f9f10d8eba9
RDX: 0000000000000038 RSI: 0000200000000780 RDI: 000000000000001a
RBP: 00007f9f10e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9f10fd6128 R14: 00007f9f10fd6090 R15: 00007ffdaedbc198
</TASK>
rcu: rcu_preempt kthread starved for 10510 jiffies! g28753 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:27200 pid:16 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
schedule+0xb9/0x180 kernel/sched/core.c:6637
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7098 Comm: syz.0.483 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:207 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:147 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:254 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:206
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 89 f6 31 d2 e9 ef c7 f7 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc900001e0e38 EFLAGS: 00000046
RAX: 00000000000048bf RBX: 00000000000048bf RCX: 0000000000000838
RDX: 0000000000000000 RSI: 00000000000048bf RDI: 0000000000000838
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffffbfff1c3eea6
R10: fffffbfff1c3eea6 R11: 1ffffffff1c3eea5 R12: dffffc0000000000
R13: 0000000010005df3 R14: ffffffff8c5e4b40 R15: dffffc0000000000
FS: 00007feceef486c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000f7d000 CR3: 000000002e8d8000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
apic_write arch/x86/include/asm/apic.h:394 [inline]
lapic_next_event+0x5b/0x70 arch/x86/kernel/apic/apic.c:478
clockevents_program_event+0x1bc/0x310 kernel/time/clockevents.c:334
hrtimer_interrupt+0x59d/0x9c0 kernel/time/hrtimer.c:1891
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc9001fd7f9e0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 5b5a7f4a0918e200
RDX: 0000000000000000 RSI: ffffffff8a8c1680 RDI: ffffffff8adefca0
RBP: ffffc9001fd7faf0 R08: dffffc0000000000 R09: fffffbfff215c44f
R10: fffffbfff215c44f R11: 1ffffffff215c44e R12: 0000000000000001
R13: 1ffff92003faff48 R14: 0000000000000246 R15: dffffc0000000000
__might_fault+0xc2/0x120 mm/memory.c:5852
__copy_from_user include/linux/uaccess.h:75 [inline]
check_xstate_in_sigframe arch/x86/kernel/fpu/signal.c:35 [inline]
__fpu_restore_sig arch/x86/kernel/fpu/signal.c:348 [inline]
fpu__restore_sig+0x203/0x1190 arch/x86/kernel/fpu/signal.c:493
restore_sigcontext arch/x86/kernel/signal.c:140 [inline]
__ia32_sys_rt_sigreturn+0x649/0x790 arch/x86/kernel/signal.c:675
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fecee18eba7
Code: ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89
RSP: 002b:00007feceef48038 EFLAGS: 00000246
RAX: 000000000000002f RBX: 00007fecee3d5fa0 RCX: 00007fecee18eba9
RDX: 0000000000002020 RSI: 0000200000000480 RDI: 0000000000000008
RBP: 00007fecee211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fecee3d6038 R14: 00007fecee3d5fa0 R15: 00007fffefc856e8
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot
Sep 16, 2025, 11:39:25 PM9/16/25
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:
HEAD commit: 3db754f56897 Linux 6.1.152
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14ea7762580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/662de00db314/disk-3db754f5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/74288f70f46c/vmlinux-3db754f5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ab4512d1fabb/bzImage-3db754f5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0c669...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
(detected by 1, t=10502 jiffies, g=10485, q=164 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4294960674-4294950173), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g10485 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
NMI backtrace for cpu 0
CPU: 0 PID: 4538 Comm: syz.4.21 Not tainted syzkaller #0
Code: 89 f6 e8 dd 3e 17 fa e9 6e ff ff ff 00 00 cc cc 00 00 cc cc 48 c7 c7 40 fc de 8a 48 c7 c6 80 fc de 8a eb 00 55 41 57 41 56 53 <48> 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 65 8b 05 a1
RSP: 0018:ffffc90000007f80 EFLAGS: 00000083
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81363ccb
RDX: 0000000000000000 RSI: ffffffff8adefc80 RDI: ffffffff8adefc40
FS: 00007f4f5f2aa6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
rcu_is_watching+0x11/0xa0 kernel/rcu/tree.c:721
trace_local_timer_exit arch/x86/include/asm/trace/irq_vectors.h:41 [inline]
__sysvec_apic_timer_interrupt+0x1aa/0x5a0 arch/x86/kernel/apic/apic.c:1125
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x62/0x290 mm/kasan/generic.c:189
Code: ff df 49 89 fb 49 c1 eb 03 49 b8 00 00 00 00 00 fc ff df 4f 8d 0c 03 48 8d 5c 37 ff 48 c1 eb 03 4e 8d 14 3b 4d 89 d6 4d 29 ce <49> 83 fe 10 7f 26 4d 85 f6 0f 84 39 01 00 00 48 f7 d3 4c 01 db 41
RSP: 0018:ffffc90003887cb0 EFLAGS: 00000216
RAX: ffffffff84070701 RBX: 1ffff92000710fc3 RCX: ffffffff84070807
RDX: 0000000000000001 RSI: 00000000000000c0 RDI: ffffc90003887d60
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffff52000710fac
R10: fffff52000710fc4 R11: 1ffff92000710fac R12: 00007fffffffef40
R13: 1ffff92000710ffe R14: 0000000000000018 R15: dffffc0000000001
instrument_copy_from_user_before include/linux/instrumented.h:137 [inline]
_copy_from_user+0xe7/0x170 lib/usercopy.c:22
copy_from_user include/linux/uaccess.h:161 [inline]
restore_sigcontext arch/x86/kernel/signal.c:92 [inline]
__ia32_sys_rt_sigreturn+0x1e6/0x790 arch/x86/kernel/signal.c:675
Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25
RSP: 002b:00007f4f5f2a9b40 EFLAGS: 00000206 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f4f5e5d5fa8 RCX: 00007f4f5e32ada9
RDX: 00007f4f5f2a9b40 RSI: 00007f4f5f2a9c70 RDI: 0000000000000021
RBP: 00007f4f5e5d5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f4f5e5d6038 R14: 00007ffd7ffe4e20 R15: 00007ffd7ffe4f08
</TASK>
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
HEAD commit: 3db754f56897 Linux 6.1.152
git tree: linux-6.1.y
kernel config: https://syzkaller.appspot.com/x/.config?x=7eb38bd5021fec61
dashboard link: https://syzkaller.appspot.com/bug?extid=b0c669c304df2c205c64
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1418af62580000
dashboard link: https://syzkaller.appspot.com/bug?extid=b0c669c304df2c205c64
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/662de00db314/disk-3db754f5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/74288f70f46c/vmlinux-3db754f5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ab4512d1fabb/bzImage-3db754f5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0c669...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4294960674-4294950173), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g10485 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:27840 pid:16 ppid:2 flags:0x00004000
rcu: RCU grace-period kthread stack dump:
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
schedule+0xb9/0x180 kernel/sched/core.c:6637
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
schedule+0xb9/0x180 kernel/sched/core.c:6637
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 4538 Comm: syz.4.21 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:check_preemption_disabled+0x6/0x110 lib/smp_processor_id.c:13
Code: 89 f6 e8 dd 3e 17 fa e9 6e ff ff ff 00 00 cc cc 00 00 cc cc 48 c7 c7 40 fc de 8a 48 c7 c6 80 fc de 8a eb 00 55 41 57 41 56 53 <48> 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 65 8b 05 a1
RSP: 0018:ffffc90000007f80 EFLAGS: 00000083
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81363ccb
RDX: 0000000000000000 RSI: ffffffff8adefc80 RDI: ffffffff8adefc40
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffffbfff1c3eea6
R10: fffffbfff1c3eea6 R11: 1ffffffff1c3eea5 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
R10: fffffbfff1c3eea6 R11: 1ffffffff1c3eea5 R12: dffffc0000000000
FS: 00007f4f5f2aa6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000005cadb000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline]
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
rcu_is_watching+0x11/0xa0 kernel/rcu/tree.c:721
trace_local_timer_exit arch/x86/include/asm/trace/irq_vectors.h:41 [inline]
__sysvec_apic_timer_interrupt+0x1aa/0x5a0 arch/x86/kernel/apic/apic.c:1125
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:101 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x62/0x290 mm/kasan/generic.c:189
Code: ff df 49 89 fb 49 c1 eb 03 49 b8 00 00 00 00 00 fc ff df 4f 8d 0c 03 48 8d 5c 37 ff 48 c1 eb 03 4e 8d 14 3b 4d 89 d6 4d 29 ce <49> 83 fe 10 7f 26 4d 85 f6 0f 84 39 01 00 00 48 f7 d3 4c 01 db 41
RSP: 0018:ffffc90003887cb0 EFLAGS: 00000216
RAX: ffffffff84070701 RBX: 1ffff92000710fc3 RCX: ffffffff84070807
RDX: 0000000000000001 RSI: 00000000000000c0 RDI: ffffc90003887d60
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffff52000710fac
R10: fffff52000710fc4 R11: 1ffff92000710fac R12: 00007fffffffef40
R13: 1ffff92000710ffe R14: 0000000000000018 R15: dffffc0000000001
instrument_copy_from_user_before include/linux/instrumented.h:137 [inline]
_copy_from_user+0xe7/0x170 lib/usercopy.c:22
copy_from_user include/linux/uaccess.h:161 [inline]
restore_sigcontext arch/x86/kernel/signal.c:92 [inline]
__ia32_sys_rt_sigreturn+0x1e6/0x790 arch/x86/kernel/signal.c:675
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4f5e32ada9
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25
RSP: 002b:00007f4f5f2a9b40 EFLAGS: 00000206 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f4f5e5d5fa8 RCX: 00007f4f5e32ada9
RDX: 00007f4f5f2a9b40 RSI: 00007f4f5f2a9c70 RDI: 0000000000000021
RBP: 00007f4f5e5d5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f4f5e5d6038 R14: 00007ffd7ffe4e20 R15: 00007ffd7ffe4f08
</TASK>
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
syzbot
Jun 21, 2026, 5:37:32 PM (4 days ago) Jun 21
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:
HEAD commit: fdb6fcb41cc7 Linux 6.1.176
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1558cd56580000
kernel config: https://syzkaller.appspot.com/x/.config?x=acfbe65fbce84c0c
dashboard link: https://syzkaller.appspot.com/bug?extid=b0c669c304df2c205c64
compiler: Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1036d766580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16af5b7a580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1609e67fe610/disk-fdb6fcb4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7c9914a35256/vmlinux-fdb6fcb4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/401dd54d7ec6/bzImage-fdb6fcb4.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0c669...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 1-...!: (10499 ticks this GP) idle=efac/1/0x4000000000000000 softirq=11118/11127 fqs=0
(t=10501 jiffies g=11873 q=106 ncpus=2)
rcu: rcu_preempt kthread starved for 10502 jiffies! g11873 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6562
schedule+0xb9/0x180 kernel/sched/core.c:6638
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x303/0x1350 kernel/rcu/tree.c:1706
rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:trace_lock_release include/trace/events/lock.h:69 [inline]
RIP: 0010:lock_release+0xc8/0x920 kernel/locking/lockdep.c:5673
Code: fe 9b bb 0c 0f 83 3a 05 00 00 41 89 de c1 eb 06 48 8d 3c dd 68 0f 20 8e be 08 00 00 00 e8 d0 d4 6e 00 4c 0f a3 35 d0 99 bb 0c <73> 0d e8 81 ac 07 00 84 c0 0f 84 41 05 00 00 48 c7 c0 24 44 20 8e
RSP: 0018:ffffc90000007ba0 EFLAGS: 00000057
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81647590
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e200f68
RBP: ffffc90000007cb0 R08: ffffffff8e200f6f R09: 1ffffffff1c401ed
R10: dffffc0000000000 R11: fffffbfff1c401ee R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff92000000f80
FS: 00007f02471a66c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
_raw_spin_unlock_irqrestore+0x6d/0x120 kernel/locking/spinlock.c:194
debug_hrtimer_deactivate kernel/time/hrtimer.c:453 [inline]
__run_hrtimer kernel/time/hrtimer.c:1719 [inline]
__hrtimer_run_queues+0x2d8/0xc90 kernel/time/hrtimer.c:1815
hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877
Code: ec e0 00 00 00 48 89 74 24 30 48 89 7c 24 10 65 48 8b 04 25 28 00 00 00 48 89 84 24 c0 00 00 00 49 bd 00 00 00 00 00 fc ff df <48> c7 44 24 60 b3 8a b5 41 48 c7 44 24 68 51 db 42 8c 48 c7 44 24
RSP: 0018:ffffc900034d7a00 EFLAGS: 00000286
RAX: b561f75630bd3300 RBX: 0000000000000000 RCX: b561f75630bd3300
RDX: 0000000000000000 RSI: ffffffff81c058d6 RDI: ffff88801746ae58
RBP: ffffc900034d7b10 R08: dffffc0000000000 R09: 1ffffffff215e44e
R10: dffffc0000000000 R11: fffffbfff215e44f R12: 1ffff9200069af70
R13: dffffc0000000000 R14: ffffc900034d7c30 R15: dffffc0000000000
restore_sigcontext arch/x86/kernel/signal.c:140 [inline]
__ia32_sys_rt_sigreturn+0x5ef/0x750 arch/x86/kernel/signal.c:675
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f024639ce57
Code: 83 c8 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
RSP: 002b:00007f02471a60e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f0246615fa8 RCX: 00007f024639ce59
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f0246615fa8
RBP: 00007f0246615fa0 R08: 0000000000000000 R09: 0000000000000000
</TASK>
CPU: 1 PID: 4517 Comm: syz.0.35 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 0e 82 2f f7 48 89 df e8 76 49 30 f7 e8 01 95 53 f7 fb bf 01 00 00 00 <e8> 66 cb 23 f7 65 8b 05 67 7c cd 75 85 c0 74 02 5b c3 e8 74 90 cb
RSP: 0018:ffffc90003557b98 EFLAGS: 00000282
RAX: e6fef6a2bfccf400 RBX: ffff88802e325c80 RCX: e6fef6a2bfccf400
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffff88802e325c83 R09: 1ffff11005c64b90
R10: dffffc0000000000 R11: ffffed1005c64b91 R12: 0000000000000021
R13: ffff88802e326118 R14: dffffc0000000000 R15: 000000001c000004
FS: 00007fefbaa6a6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
spin_unlock_irq include/linux/spinlock.h:401 [inline]
get_signal+0x114a/0x1340 kernel/signal.c:2875
arch_do_signal_or_restart+0xc4/0x1310 arch/x86/kernel/signal.c:871
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fefb9b9ce57
Code: 83 c8 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
RSP: 002b:00007fefbaa6a0e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007fefb9e15fa8 RCX: 00007fefb9b9ce59
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fefb9e15fa8
RBP: 00007fefb9e15fa0 R08: 0000000000000000 R09: 0000000000000000
</TASK>
sched: RT throttling activated
HEAD commit: fdb6fcb41cc7 Linux 6.1.176
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1558cd56580000
kernel config: https://syzkaller.appspot.com/x/.config?x=acfbe65fbce84c0c
dashboard link: https://syzkaller.appspot.com/bug?extid=b0c669c304df2c205c64
compiler: Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1036d766580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16af5b7a580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1609e67fe610/disk-fdb6fcb4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7c9914a35256/vmlinux-fdb6fcb4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/401dd54d7ec6/bzImage-fdb6fcb4.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0c669...@syzkaller.appspotmail.com
rcu: 1-...!: (10499 ticks this GP) idle=efac/1/0x4000000000000000 softirq=11118/11127 fqs=0
(t=10501 jiffies g=11873 q=106 ncpus=2)
rcu: rcu_preempt kthread starved for 10502 jiffies! g11873 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:27888 pid:16 ppid:2 flags:0x00004000
rcu: RCU grace-period kthread stack dump:
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6562
schedule+0xb9/0x180 kernel/sched/core.c:6638
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x303/0x1350 kernel/rcu/tree.c:1706
rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4519 Comm: syz.1.36 Not tainted syzkaller #0
NMI backtrace for cpu 0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:trace_lock_release include/trace/events/lock.h:69 [inline]
RIP: 0010:lock_release+0xc8/0x920 kernel/locking/lockdep.c:5673
Code: fe 9b bb 0c 0f 83 3a 05 00 00 41 89 de c1 eb 06 48 8d 3c dd 68 0f 20 8e be 08 00 00 00 e8 d0 d4 6e 00 4c 0f a3 35 d0 99 bb 0c <73> 0d e8 81 ac 07 00 84 c0 0f 84 41 05 00 00 48 c7 c0 24 44 20 8e
RSP: 0018:ffffc90000007ba0 EFLAGS: 00000057
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81647590
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e200f68
RBP: ffffc90000007cb0 R08: ffffffff8e200f6f R09: 1ffffffff1c401ed
R10: dffffc0000000000 R11: fffffbfff1c401ee R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff92000000f80
FS: 00007f02471a66c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000007210f000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:149 [inline]
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
_raw_spin_unlock_irqrestore+0x6d/0x120 kernel/locking/spinlock.c:194
debug_hrtimer_deactivate kernel/time/hrtimer.c:453 [inline]
__run_hrtimer kernel/time/hrtimer.c:1719 [inline]
__hrtimer_run_queues+0x2d8/0xc90 kernel/time/hrtimer.c:1815
hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_release+0x3d/0x920 kernel/locking/lockdep.c:5670
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
Code: ec e0 00 00 00 48 89 74 24 30 48 89 7c 24 10 65 48 8b 04 25 28 00 00 00 48 89 84 24 c0 00 00 00 49 bd 00 00 00 00 00 fc ff df <48> c7 44 24 60 b3 8a b5 41 48 c7 44 24 68 51 db 42 8c 48 c7 44 24
RSP: 0018:ffffc900034d7a00 EFLAGS: 00000286
RAX: b561f75630bd3300 RBX: 0000000000000000 RCX: b561f75630bd3300
RDX: 0000000000000000 RSI: ffffffff81c058d6 RDI: ffff88801746ae58
RBP: ffffc900034d7b10 R08: dffffc0000000000 R09: 1ffffffff215e44e
R10: dffffc0000000000 R11: fffffbfff215e44f R12: 1ffff9200069af70
R13: dffffc0000000000 R14: ffffc900034d7c30 R15: dffffc0000000000
__copy_from_user include/linux/uaccess.h:75 [inline]
check_xstate_in_sigframe arch/x86/kernel/fpu/signal.c:35 [inline]
__fpu_restore_sig arch/x86/kernel/fpu/signal.c:348 [inline]
fpu__restore_sig+0x245/0x12d0 arch/x86/kernel/fpu/signal.c:493
check_xstate_in_sigframe arch/x86/kernel/fpu/signal.c:35 [inline]
__fpu_restore_sig arch/x86/kernel/fpu/signal.c:348 [inline]
restore_sigcontext arch/x86/kernel/signal.c:140 [inline]
__ia32_sys_rt_sigreturn+0x5ef/0x750 arch/x86/kernel/signal.c:675
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f024639ce57
Code: 83 c8 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
RSP: 002b:00007f02471a60e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f0246615fa8 RCX: 00007f024639ce59
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f0246615fa8
RBP: 00007f0246615fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0246616038 R14: 00007ffca095c540 R15: 00007ffca095c628
</TASK>
CPU: 1 PID: 4517 Comm: syz.0.35 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 0e 82 2f f7 48 89 df e8 76 49 30 f7 e8 01 95 53 f7 fb bf 01 00 00 00 <e8> 66 cb 23 f7 65 8b 05 67 7c cd 75 85 c0 74 02 5b c3 e8 74 90 cb
RSP: 0018:ffffc90003557b98 EFLAGS: 00000282
RAX: e6fef6a2bfccf400 RBX: ffff88802e325c80 RCX: e6fef6a2bfccf400
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffff88802e325c83 R09: 1ffff11005c64b90
R10: dffffc0000000000 R11: ffffed1005c64b91 R12: 0000000000000021
R13: ffff88802e326118 R14: dffffc0000000000 R15: 000000001c000004
FS: 00007fefbaa6a6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000005b06d000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
spin_unlock_irq include/linux/spinlock.h:401 [inline]
get_signal+0x114a/0x1340 kernel/signal.c:2875
arch_do_signal_or_restart+0xc4/0x1310 arch/x86/kernel/signal.c:871
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fefb9b9ce57
Code: 83 c8 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
RSP: 002b:00007fefbaa6a0e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007fefb9e15fa8 RCX: 00007fefb9b9ce59
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fefb9e15fa8
RBP: 00007fefb9e15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fefb9e16038 R14: 00007fff4e986590 R15: 00007fff4e986678
</TASK>
sched: RT throttling activated
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