[v6.1] INFO: rcu detected stall in sys_mkdir (2)
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syzbot
1:04 AM (4 hours ago) 1:04 AM
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Hello,
syzbot found the following issue on:
HEAD commit: 50cbba13faa2 Linux 6.1.159
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=165ddb1a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6a5cbd268406bf43
dashboard link: https://syzkaller.appspot.com/bug?extid=8469452c867bc303645b
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=126f0b58580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15255392580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/50ceb00b1b39/disk-50cbba13.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ebb8883b9a29/vmlinux-50cbba13.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7edc2a795f03/bzImage-50cbba13.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+846945...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4268/1:b..l
(detected by 1, t=10503 jiffies, g=5749, q=25 ncpus=2)
task:syz-executor351 state:R running task stack:26240 pid:4268 ppid:4263 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
irqentry_exit+0x63/0x70 kernel/entry/common.c:439
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:preempt_count_sub+0x61/0x160 kernel/sched/core.c:5749
Code: ff ff ff 7f 39 cf 7f 25 81 ff ff 00 00 00 0f 93 c1 84 c0 0f 95 c0 08 c8 74 53 65 8b 05 40 ad aa 7e f7 df 65 01 3d 37 ad aa 7e <5b> 5d c3 e8 d7 40 ac 02 85 c0 74 f4 48 c7 c0 e8 42 ff 8d 48 c1 e8
RSP: 0018:ffffc90003cc7a70 EFLAGS: 00000297
RAX: 0000000080000001 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 00000000ffffffff
RBP: 0000000000000001 R08: dffffc0000000000 R09: ffffed100eb0fc42
R10: ffffed100eb0fc42 R11: 1ffff1100eb0fc41 R12: 1ffff1100eb0fc49
R13: 0000000000000000 R14: ffff88807587e248 R15: dffffc0000000000
__raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_unlock+0x24/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:391 [inline]
lockref_get_not_dead+0x72/0xb0 lib/lockref.c:190
__legitimize_path fs/namei.c:708 [inline]
legitimize_path fs/namei.c:718 [inline]
try_to_unlazy+0x125/0x5a0 fs/namei.c:779
complete_walk+0x113/0x350 fs/namei.c:888
path_parentat fs/namei.c:2536 [inline]
__filename_parentat+0x221/0x610 fs/namei.c:2558
filename_parentat fs/namei.c:2576 [inline]
filename_create+0xcc/0x450 fs/namei.c:3865
do_mkdirat+0x9d/0x430 fs/namei.c:4129
__do_sys_mkdir fs/namei.c:4159 [inline]
__se_sys_mkdir fs/namei.c:4157 [inline]
__x64_sys_mkdir+0x6a/0x80 fs/namei.c:4157
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: 0033:0x7f04215e2e97
RSP: 002b:00007ffea8dd6b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007f042163b0ae RCX: 00007f04215e2e97
RDX: 00007f042163b101 RSI: 00000000000001c0 RDI: 00007f042163b106
RBP: 00007f042163b0e6 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f042164133c
R13: 00007f042163b106 R14: 0000000000000000 R15: 0000000000000000
</TASK>
rcu: rcu_preempt kthread starved for 10533 jiffies! g5749 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:28192 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:2168
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:
NMI backtrace for cpu 0
CPU: 0 PID: 4293 Comm: syz-executor351 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__kasan_check_read+0x0/0x10 mm/kasan/shadow.c:31
Code: 41 5c 41 5d 41 5e 41 5f 5d c3 48 c7 c7 fa c5 39 8c eb 0a 48 c7 c7 ec 2d 23 8c 48 89 de e8 68 53 34 08 31 ed eb d7 00 00 cc cc <89> f6 48 8b 0c 24 31 d2 e9 a3 ec ff ff 0f 1f 00 89 f6 48 8b 0c 24
RSP: 0018:ffffc90003e374f8 EFLAGS: 00000002
RAX: 0000000000000008 RBX: 0000000000000048 RCX: ffffffff81630c92
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffffffff908c8248
RBP: ffffc90003e37750 R08: dffffc0000000000 R09: fffffbfff211904a
R10: fffffbfff211904a R11: 1ffffffff2119049 R12: ffff888079783b80
R13: 0000000000000008 R14: 0000000000000000 R15: ffff8880797846d0
FS: 0000555580f67480(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 00000000299eb000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
instrument_atomic_read include/linux/instrumented.h:72 [inline]
_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
hlock_class kernel/locking/lockdep.c:228 [inline]
check_wait_context kernel/locking/lockdep.c:4724 [inline]
__lock_acquire+0x5e3/0x7c50 kernel/locking/lockdep.c:4999
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
seqcount_lockdep_reader_access+0xc6/0x1c0 include/linux/seqlock.h:102
timekeeping_get_delta kernel/time/timekeeping.c:254 [inline]
timekeeping_get_ns kernel/time/timekeeping.c:388 [inline]
ktime_get+0x7b/0x270 kernel/time/timekeeping.c:848
clockevents_program_min_delta+0x55/0x340 kernel/time/clockevents.c:241
hrtimer_start_range_ns+0xb9a/0xfc0 kernel/time/hrtimer.c:1349
posixtimer_rearm+0x131/0x340 kernel/time/posix-timers.c:329
dequeue_signal+0x1b6/0x4b0 kernel/signal.c:704
get_signal+0x547/0x1350 kernel/signal.c:2751
arch_do_signal_or_restart+0xb7/0x1240 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:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f04215e4119
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 19 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffea8dd6958 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f04215e4119
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 00007f042164133c R09: 00007f042164133c
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f042164133c
R13: 00007f042163b106 R14: 00007ffea8dd69a0 R15: 0000000000000000
</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 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.
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: 50cbba13faa2 Linux 6.1.159
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=165ddb1a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6a5cbd268406bf43
dashboard link: https://syzkaller.appspot.com/bug?extid=8469452c867bc303645b
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=126f0b58580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15255392580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/50ceb00b1b39/disk-50cbba13.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ebb8883b9a29/vmlinux-50cbba13.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7edc2a795f03/bzImage-50cbba13.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+846945...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4268/1:b..l
(detected by 1, t=10503 jiffies, g=5749, q=25 ncpus=2)
task:syz-executor351 state:R running task stack:26240 pid:4268 ppid:4263 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
irqentry_exit+0x63/0x70 kernel/entry/common.c:439
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:preempt_count_sub+0x61/0x160 kernel/sched/core.c:5749
Code: ff ff ff 7f 39 cf 7f 25 81 ff ff 00 00 00 0f 93 c1 84 c0 0f 95 c0 08 c8 74 53 65 8b 05 40 ad aa 7e f7 df 65 01 3d 37 ad aa 7e <5b> 5d c3 e8 d7 40 ac 02 85 c0 74 f4 48 c7 c0 e8 42 ff 8d 48 c1 e8
RSP: 0018:ffffc90003cc7a70 EFLAGS: 00000297
RAX: 0000000080000001 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 00000000ffffffff
RBP: 0000000000000001 R08: dffffc0000000000 R09: ffffed100eb0fc42
R10: ffffed100eb0fc42 R11: 1ffff1100eb0fc41 R12: 1ffff1100eb0fc49
R13: 0000000000000000 R14: ffff88807587e248 R15: dffffc0000000000
__raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_unlock+0x24/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:391 [inline]
lockref_get_not_dead+0x72/0xb0 lib/lockref.c:190
__legitimize_path fs/namei.c:708 [inline]
legitimize_path fs/namei.c:718 [inline]
try_to_unlazy+0x125/0x5a0 fs/namei.c:779
complete_walk+0x113/0x350 fs/namei.c:888
path_parentat fs/namei.c:2536 [inline]
__filename_parentat+0x221/0x610 fs/namei.c:2558
filename_parentat fs/namei.c:2576 [inline]
filename_create+0xcc/0x450 fs/namei.c:3865
do_mkdirat+0x9d/0x430 fs/namei.c:4129
__do_sys_mkdir fs/namei.c:4159 [inline]
__se_sys_mkdir fs/namei.c:4157 [inline]
__x64_sys_mkdir+0x6a/0x80 fs/namei.c:4157
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: 0033:0x7f04215e2e97
RSP: 002b:00007ffea8dd6b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007f042163b0ae RCX: 00007f04215e2e97
RDX: 00007f042163b101 RSI: 00000000000001c0 RDI: 00007f042163b106
RBP: 00007f042163b0e6 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f042164133c
R13: 00007f042163b106 R14: 0000000000000000 R15: 0000000000000000
</TASK>
rcu: rcu_preempt kthread starved for 10533 jiffies! g5749 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:28192 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:2168
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:
NMI backtrace for cpu 0
CPU: 0 PID: 4293 Comm: syz-executor351 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__kasan_check_read+0x0/0x10 mm/kasan/shadow.c:31
Code: 41 5c 41 5d 41 5e 41 5f 5d c3 48 c7 c7 fa c5 39 8c eb 0a 48 c7 c7 ec 2d 23 8c 48 89 de e8 68 53 34 08 31 ed eb d7 00 00 cc cc <89> f6 48 8b 0c 24 31 d2 e9 a3 ec ff ff 0f 1f 00 89 f6 48 8b 0c 24
RSP: 0018:ffffc90003e374f8 EFLAGS: 00000002
RAX: 0000000000000008 RBX: 0000000000000048 RCX: ffffffff81630c92
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffffffff908c8248
RBP: ffffc90003e37750 R08: dffffc0000000000 R09: fffffbfff211904a
R10: fffffbfff211904a R11: 1ffffffff2119049 R12: ffff888079783b80
R13: 0000000000000008 R14: 0000000000000000 R15: ffff8880797846d0
FS: 0000555580f67480(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 00000000299eb000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
instrument_atomic_read include/linux/instrumented.h:72 [inline]
_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
hlock_class kernel/locking/lockdep.c:228 [inline]
check_wait_context kernel/locking/lockdep.c:4724 [inline]
__lock_acquire+0x5e3/0x7c50 kernel/locking/lockdep.c:4999
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
seqcount_lockdep_reader_access+0xc6/0x1c0 include/linux/seqlock.h:102
timekeeping_get_delta kernel/time/timekeeping.c:254 [inline]
timekeeping_get_ns kernel/time/timekeeping.c:388 [inline]
ktime_get+0x7b/0x270 kernel/time/timekeeping.c:848
clockevents_program_min_delta+0x55/0x340 kernel/time/clockevents.c:241
hrtimer_start_range_ns+0xb9a/0xfc0 kernel/time/hrtimer.c:1349
posixtimer_rearm+0x131/0x340 kernel/time/posix-timers.c:329
dequeue_signal+0x1b6/0x4b0 kernel/signal.c:704
get_signal+0x547/0x1350 kernel/signal.c:2751
arch_do_signal_or_restart+0xb7/0x1240 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:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f04215e4119
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 19 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffea8dd6958 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f04215e4119
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 00007f042164133c R09: 00007f042164133c
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f042164133c
R13: 00007f042163b106 R14: 00007ffea8dd69a0 R15: 0000000000000000
</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 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.
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
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