syzbot

 sign-in | mailing list | source | docs
🐞 Open [1609]
≡ Subsystems
🐞 Fixed [6289]
🐞 Invalid [16007]
⬇ Missing Backports [189]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

INFO: rcu detected stall in sys_unlinkat

Status: auto-obsoleted due to no activity on 2023/07/13 16:11
Subsystems: net ext4
[Documentation on labels]
First crash: 993d, last: 791d
▶ ▼ Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_unlinkat (3) mm 30 11d 7d20h 0/28 upstream: reported on 2025/06/06 14:28
upstream INFO: rcu detected stall in sys_unlinkat (2) tomoyo 1 657d 657d 0/28 auto-obsoleted due to no activity on 2023/11/25 04:08
linux-5.15 INFO: rcu detected stall in sys_unlinkat 1 362d 362d 0/3 auto-obsoleted due to no activity on 2024/09/24 13:32

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10499 ticks this GP) idle=0aec/1/0x4000000000000000 softirq=18496/18496 fqs=0
	(t=10500 jiffies g=22345 q=49 ncpus=2)
rcu: rcu_preempt kthread timer wakeup didn't happen for 10499 jiffies! g22345 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=27208
rcu: rcu_preempt kthread starved for 10500 jiffies! g22345 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27872 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5293 [inline]
 __schedule+0xb8a/0x5450 kernel/sched/core.c:6606
 schedule+0xde/0x1b0 kernel/sched/core.c:6682
 schedule_timeout+0x14e/0x2a0 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x190/0x910 kernel/rcu/tree.c:1656
 rcu_gp_kthread+0x23a/0x360 kernel/rcu/tree.c:1855
 kthread+0x2e8/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </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: 5113 Comm: syz-executor.4 Not tainted 6.2.0-rc6-syzkaller-00163-g66a87fff1a87 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
RIP: 0010:rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:121 [inline]
RIP: 0010:rcu_is_watching+0x12/0xb0 kernel/rcu/tree.c:713
Code: db 4d 8a e8 70 ac 9d 08 65 8a 05 15 16 99 7e 0f b6 c0 c3 0f 1f 44 00 00 f3 0f 1e fa 55 53 65 ff 05 5b fc 98 7e e8 2e ac 9d 08 <48> c7 c3 28 60 03 00 83 f8 07 89 c5 77 7a 48 8d 3c ed 00 b9 13 8c
RSP: 0018:ffffc900001e0c88 EFLAGS: 00000006
RAX: 0000000000000001 RBX: 1ffff9200003c199 RCX: ffffffff81639710
RDX: dffffc0000000000 RSI: 0000000000010006 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8e733897
R10: fffffbfff1ce6712 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: ffff88807a9f0300 R15: 0000000000000000
FS:  0000555555987400(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff4961ad988 CR3: 0000000034aee000 CR4: 0000000000350ee0
Call Trace:
 <IRQ>
 rcu_read_lock_held_common kernel/rcu/update.c:108 [inline]
 rcu_read_lock_sched_held+0x20/0x70 kernel/rcu/update.c:123
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0x500/0x630 kernel/locking/lockdep.c:5639
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:350 [inline]
 advance_sched+0x57/0x9b0 net/sched/sch_taprio.c:700
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x690/0xfb0 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x320/0x790 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1096 [inline]
 __sysvec_apic_timer_interrupt+0x180/0x640 arch/x86/kernel/apic/apic.c:1113
 sysvec_apic_timer_interrupt+0x92/0xc0 arch/x86/kernel/apic/apic.c:1107
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:200
Code: e6 00 8a 02 66 0f 1f 44 00 00 f3 0f 1e fa 48 8b be a8 01 00 00 e8 b0 ff ff ff 31 c0 c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 <f3> 0f 1e fa 65 8b 05 1d b9 82 7e 89 c1 48 8b 34 24 81 e1 00 01 00
RSP: 0018:ffffc900042cf660 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff823b4295
RDX: ffff88801f953a80 RSI: 0000000000000000 RDI: 0000000000000005
RBP: ffff8880777a4bc8 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888077416f00
R13: ffffed100eef4979 R14: ffff888073b58c00 R15: ffff88802aa7c768
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 bit_spin_unlock include/linux/bit_spinlock.h:60 [inline]
 jbd_unlock_bh_journal_head include/linux/jbd2.h:357 [inline]
 jbd2_journal_put_journal_head+0x3c3/0x5f0 fs/jbd2/journal.c:3029
 jbd2_journal_forget+0x505/0x790 fs/jbd2/transaction.c:1730
 jbd2_journal_revoke+0x21a/0x550 fs/jbd2/revoke.c:393
 __ext4_forget+0x24e/0x570 fs/ext4/ext4_jbd2.c:308
 ext4_free_blocks+0x1b50/0x2300 fs/ext4/mballoc.c:6169
 ext4_remove_blocks fs/ext4/extents.c:2545 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2710 [inline]
 ext4_ext_remove_space+0x203c/0x46e0 fs/ext4/extents.c:2958
 ext4_ext_truncate+0x34b/0x400 fs/ext4/extents.c:4416
 ext4_truncate+0xfea/0x15d0 fs/ext4/inode.c:4342
 ext4_evict_inode+0xc00/0x1eb0 fs/ext4/inode.c:286
 evict+0x2ed/0x6b0 fs/inode.c:664
 iput_final fs/inode.c:1747 [inline]
 iput.part.0+0x59b/0x880 fs/inode.c:1773
 iput+0x5c/0x80 fs/inode.c:1763
 d_delete_notify include/linux/fsnotify.h:261 [inline]
 vfs_rmdir.part.0+0x496/0x5a0 fs/namei.c:4134
 vfs_rmdir fs/namei.c:4106 [inline]
 do_rmdir+0x395/0x410 fs/namei.c:4182
 __do_sys_unlinkat fs/namei.c:4362 [inline]
 __se_sys_unlinkat fs/namei.c:4356 [inline]
 __x64_sys_unlinkat+0xef/0x130 fs/namei.c:4356
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f8a6d08ba67
Code: 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 07 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffb334bb58 EFLAGS: 00000207 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 00007f8a6d08ba67
RDX: 0000000000000200 RSI: 00007fffb334cce0 RDI: 00000000ffffff9c
RBP: 00007fffb334bc20 R08: 0000000000000000 R09: 00007fffb334b9f0
R10: 00005555559888e3 R11: 0000000000000207 R12: 00007f8a6d0e6b24
R13: 00007fffb334cce0 R14: 0000555555988810 R15: 00007fffb334cd20
 </TASK>
CPU: 0 PID: 9030 Comm: syz-executor.2 Not tainted 6.2.0-rc6-syzkaller-00163-g66a87fff1a87 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
RIP: 0010:csd_lock_wait kernel/smp.c:413 [inline]
RIP: 0010:smp_call_function_many_cond+0x444/0x10a0 kernel/smp.c:987
Code: 00 45 85 e4 74 48 48 8b 04 24 49 89 c5 83 e0 07 49 c1 ed 03 49 89 c4 4d 01 fd 41 83 c4 03 e8 b3 fe 0a 00 f3 90 41 0f b6 45 00 <41> 38 c4 7c 08 84 c0 0f 85 4e 0a 00 00 8b 43 08 31 ff 83 e0 01 41
RSP: 0018:ffffc9000512fa20 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffff8880b9941d60 RCX: 0000000000000000
RDX: ffff888025a91d40 RSI: ffffffff8175f42d RDI: 0000000000000005
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffffed10173283ad R14: 0000000000000001 R15: dffffc0000000000
FS:  00005555570b2400(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32122000 CR3: 000000002ad15000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x5a/0xa0 kernel/smp.c:1155
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1772 [inline]
 text_poke_bp_batch+0x22e/0x6b0 arch/x86/kernel/alternative.c:1963
 text_poke_flush arch/x86/kernel/alternative.c:2131 [inline]
 text_poke_flush arch/x86/kernel/alternative.c:2128 [inline]
 text_poke_finish+0x1a/0x30 arch/x86/kernel/alternative.c:2138
 arch_jump_label_transform_apply+0x17/0x30 arch/x86/kernel/jump_label.c:146
 jump_label_update+0x32f/0x410 kernel/jump_label.c:829
 static_key_disable_cpuslocked+0x156/0x1b0 kernel/jump_label.c:235
 static_key_disable+0x1a/0x20 kernel/jump_label.c:243
 tracepoint_remove_func kernel/tracepoint.c:417 [inline]
 tracepoint_probe_unregister+0x636/0xc30 kernel/tracepoint.c:551
 bpf_raw_tp_link_release+0x55/0xa0 kernel/bpf/syscall.c:3144
 bpf_link_free+0xe6/0x1b0 kernel/bpf/syscall.c:2727
 bpf_link_put+0x165/0x1b0 kernel/bpf/syscall.c:2753
 bpf_link_release+0x37/0x50 kernel/bpf/syscall.c:2762
 __fput+0x27c/0xa90 fs/file_table.c:320
 task_work_run+0x16f/0x270 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:203
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296
 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fdbece3df7b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007ffd66b565a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00007fdbece3df7b
RDX: 00007fdbeca005f0 RSI: ffffffffffffffff RDI: 0000000000000004
RBP: 00007fdbecfad980 R08: 0000000000000000 R09: 00007fdbeca00000
R10: 00007fdbeca005f8 R11: 0000000000000293 R12: 000000000008c135
R13: 00007ffd66b566a0 R14: 00007fdbecfabf80 R15: 0000000000000032
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5113 Comm: syz-executor.4 Not tainted 6.2.0-rc6-syzkaller-00163-g66a87fff1a87 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4745 [inline]
RIP: 0010:__lock_acquire+0x5ac/0x56d0 kernel/locking/lockdep.c:5005
Code: 15 0b 00 00 48 8d 5d df 48 89 e8 48 89 ea 48 c1 e8 03 83 e2 07 42 0f b6 04 08 38 d0 7f 08 84 c0 0f 85 2a 28 00 00 0f b6 43 21 <31> f0 a8 60 74 c2 41 83 c6 01 65 8b 05 fb 54 9f 7e 85 c0 0f 85 cc
RSP: 0018:ffffc900001e0b58 EFLAGS: 00000046
RAX: 0000000000000005 RBX: ffff88801f9545a8 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000040 RDI: ffffffff91344859
RBP: ffff88801f9545c9 R08: 0000000000000000 R09: dffffc0000000000
R10: fffffbfff2268558 R11: 0000000000000000 R12: ffff88801f9545d0
R13: ffff88801f953a80 R14: 0000000000000006 R15: 0000000000000007
FS:  0000555555987400(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff4961ad988 CR3: 0000000034aee000 CR4: 0000000000350ee0
Call Trace:
 <IRQ>
 lock_acquire kernel/locking/lockdep.c:5668 [inline]
 lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
 rcu_lock_acquire include/linux/rcupdate.h:325 [inline]
 rcu_read_lock include/linux/rcupdate.h:764 [inline]
 advance_sched+0x4a9/0x9b0 net/sched/sch_taprio.c:753
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x690/0xfb0 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x320/0x790 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1096 [inline]
 __sysvec_apic_timer_interrupt+0x180/0x640 arch/x86/kernel/apic/apic.c:1113
 sysvec_apic_timer_interrupt+0x92/0xc0 arch/x86/kernel/apic/apic.c:1107
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:200
Code: e6 00 8a 02 66 0f 1f 44 00 00 f3 0f 1e fa 48 8b be a8 01 00 00 e8 b0 ff ff ff 31 c0 c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 <f3> 0f 1e fa 65 8b 05 1d b9 82 7e 89 c1 48 8b 34 24 81 e1 00 01 00
RSP: 0018:ffffc900042cf660 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff823b4295
RDX: ffff88801f953a80 RSI: 0000000000000000 RDI: 0000000000000005
RBP: ffff8880777a4bc8 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888077416f00
R13: ffffed100eef4979 R14: ffff888073b58c00 R15: ffff88802aa7c768
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 bit_spin_unlock include/linux/bit_spinlock.h:60 [inline]
 jbd_unlock_bh_journal_head include/linux/jbd2.h:357 [inline]
 jbd2_journal_put_journal_head+0x3c3/0x5f0 fs/jbd2/journal.c:3029
 jbd2_journal_forget+0x505/0x790 fs/jbd2/transaction.c:1730
 jbd2_journal_revoke+0x21a/0x550 fs/jbd2/revoke.c:393
 __ext4_forget+0x24e/0x570 fs/ext4/ext4_jbd2.c:308
 ext4_free_blocks+0x1b50/0x2300 fs/ext4/mballoc.c:6169
 ext4_remove_blocks fs/ext4/extents.c:2545 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2710 [inline]
 ext4_ext_remove_space+0x203c/0x46e0 fs/ext4/extents.c:2958
 ext4_ext_truncate+0x34b/0x400 fs/ext4/extents.c:4416
 ext4_truncate+0xfea/0x15d0 fs/ext4/inode.c:4342
 ext4_evict_inode+0xc00/0x1eb0 fs/ext4/inode.c:286
 evict+0x2ed/0x6b0 fs/inode.c:664
 iput_final fs/inode.c:1747 [inline]
 iput.part.0+0x59b/0x880 fs/inode.c:1773
 iput+0x5c/0x80 fs/inode.c:1763
 d_delete_notify include/linux/fsnotify.h:261 [inline]
 vfs_rmdir.part.0+0x496/0x5a0 fs/namei.c:4134
 vfs_rmdir fs/namei.c:4106 [inline]
 do_rmdir+0x395/0x410 fs/namei.c:4182
 __do_sys_unlinkat fs/namei.c:4362 [inline]
 __se_sys_unlinkat fs/namei.c:4356 [inline]
 __x64_sys_unlinkat+0xef/0x130 fs/namei.c:4356
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f8a6d08ba67
Code: 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 07 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffb334bb58 EFLAGS: 00000207 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 00007f8a6d08ba67
RDX: 0000000000000200 RSI: 00007fffb334cce0 RDI: 00000000ffffff9c
RBP: 00007fffb334bc20 R08: 0000000000000000 R09: 00007fffb334b9f0
R10: 00005555559888e3 R11: 0000000000000207 R12: 00007f8a6d0e6b24
R13: 00007fffb334cce0 R14: 0000555555988810 R15: 00007fffb334cd20
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/02/03 18:22 upstream 66a87fff1a87 1b2f701a .config console log report info ci-upstream-kasan-gce-root INFO: rcu detected stall in sys_unlinkat
2022/09/24 19:51 upstream a63f2e7cb110 0042f2b4 .config console log report info ci-upstream-kasan-gce-root INFO: rcu detected stall in sys_unlinkat
2022/12/24 17:58 net-old 256cbafb0a9a 9da18ae8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in sys_unlinkat
2023/04/14 16:05 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 1f5b16c51aef 3cfcaa1b .config console log report info ci-upstream-gce-arm64 BUG: soft lockup in sys_unlinkat
* Struck through repros no longer work on HEAD.