INFO: rcu detected stall in kernfs_fop_write_iter (3)

Status: auto-obsoleted due to no activity on 2025/12/19 09:23
Reported-by: syzbot+32360af83d5f6edaaaf3@syzkaller.appspotmail.com
First crash: 332d, last: 332d
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in kernfs_fop_write_iter (2) net mm 1 4 471d 631d 0/29 auto-obsoleted due to no activity on 2025/07/23 14:56
linux-6.1 INFO: rcu detected stall in kernfs_fop_write_iter (4) 1 2 152d 219d 0/3 auto-obsoleted due to no activity on 2026/06/17 16:43
linux-5.15 INFO: rcu detected stall in kernfs_fop_write_iter 1 1 649d 649d 0/3 auto-obsoleted due to no activity on 2025/02/05 10:26
upstream INFO: rcu detected stall in kernfs_fop_write_iter (3) prio:low net 1 syz error error 24 28d 213d 0/29 upstream: reported syz repro on 2026/01/07 17:45
linux-6.1 INFO: rcu detected stall in kernfs_fop_write_iter (2) 1 2 732d 830d 0/3 auto-obsoleted due to no activity on 2024/11/14 04:13
linux-5.15 INFO: rcu detected stall in kernfs_fop_write_iter (2) 1 1 96d 96d 0/3 upstream: reported on 2026/05/04 00:10
upstream INFO: rcu detected stall in kernfs_fop_write_iter fs sctp 1 7 725d 821d 0/29 auto-obsoleted due to no activity on 2024/11/10 20:48
linux-6.1 INFO: rcu detected stall in kernfs_fop_write_iter 1 1 1108d 1108d 0/3 auto-obsoleted due to no activity on 2023/11/03 22:13
android-6-1 BUG: soft lockup in kernfs_fop_write_iter 1 1 452d 452d 0/2 auto-obsoleted due to no activity on 2025/08/11 05:47

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2676 jiffies s: 41489 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 14110 Comm: syz.6.3747 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:perf_trace_run_bpf_submit+0xa/0x1c0 kernel/events/core.c:9994
Code: ff ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 42 ff ff ff 48 89 df e8 a5 44 2d 00 e9 35 ff ff ff 55 41 57 41 56 41 55 41 54 53 <48> 83 ec 10 4d 89 ce 4c 89 44 24 08 49 89 cd 48 89 14 24 89 f5 49
RSP: 0018:ffffc90000007898 EFLAGS: 00000046
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffff8cb7cee0
RDX: 0000000000000001 RSI: 0000000000000014 RDI: ffffe8ffffcfa000
RBP: ffffc900000079a8 R08: 0000000000000001 R09: ffff8880b8e35518
R10: ffffed10171c6afa R11: 1ffff110171c6af9 R12: ffffe8ffffcfa000
R13: ffff8880b8e35518 R14: ffffe8ffffcfa00c R15: 1ffff92000000f20
FS:  00007f9e0f03c6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb39dbd7dac CR3: 00000000638be000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_trace_preemptirq_template+0x287/0x330 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x84/0x500 kernel/rcu/tree_plugin.h:685
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 2d 97 96 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc90000007aa0 EFLAGS: 00000206
RAX: 01995bf51fc09400 RBX: 1ffff92000000f5c RCX: 01995bf51fc09400
RDX: dffffc0000000000 RSI: ffffffff8a8c0300 RDI: ffffffff8adefaa0
RBP: ffffc90000007b90 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8e3b900 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 ieee80211_iterate_active_interfaces_atomic+0x156/0x170 net/mac80211/util.c:826
 mac80211_hwsim_beacon+0xb7/0x1b0 drivers/net/wireless/mac80211_hwsim.c:2147
 __run_hrtimer kernel/time/hrtimer.c:1752 [inline]
 __hrtimer_run_queues+0x554/0xd60 kernel/time/hrtimer.c:1816
 hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1833
 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 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:raw_spin_rq_unlock_irq+0x13/0x90 kernel/sched/sched.h:1368
Code: 7c d2 e8 90 27 77 00 eb cb 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 66 90 41 57 41 56 53 66 90 e8 e4 8f c7 08 e8 5f 62 2d 00 fb 5b <41> 5e 41 5f c3 49 be 00 00 00 00 00 fc ff df 49 89 ff 48 8d 9f 58
RSP: 0018:ffffc90004ce7428 EFLAGS: 00000282
RAX: 01995bf51fc09400 RBX: ffff8880286d3e10 RCX: 01995bf51fc09400
RDX: dffffc0000000000 RSI: ffffffff8a8c0300 RDI: ffffffff8adefaa0
RBP: ffffc90004ce75d0 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: ffff8880286d3b80
R13: dffffc0000000000 R14: ffff8880b8e3aac0 R15: ffff8880286d3b80
 __schedule+0x137c/0x40b0 kernel/sched/core.c:6567
 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 include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x36/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 __text_poke+0x680/0x810 arch/x86/kernel/alternative.c:1456
 text_poke arch/x86/kernel/alternative.c:1480 [inline]
 text_poke_bp_batch+0x13f/0x7d0 arch/x86/kernel/alternative.c:1771
 text_poke_flush arch/x86/kernel/alternative.c:1965 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1972
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 static_key_slow_inc_cpuslocked+0x7c/0xe0 kernel/jump_label.c:165
 freezer_apply_state+0x1b8/0x400 kernel/cgroup/legacy_freezer.c:357
 freezer_change_state kernel/cgroup/legacy_freezer.c:-1 [inline]
 freezer_write+0x29b/0x440 kernel/cgroup/legacy_freezer.c:432
 cgroup_file_write+0x2f8/0x660 kernel/cgroup/cgroup.c:4077
 kernfs_fop_write_iter+0x379/0x4c0 fs/kernfs/file.c:334
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x44c/0x960 fs/read_write.c:584
 ksys_write+0x143/0x240 fs/read_write.c:637
 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: 0033:0x7f9e0e18eba9
Code: 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 01 48
RSP: 002b:00007f9e0f03c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9e0e3d5fa0 RCX: 00007f9e0e18eba9
RDX: 0000000000000007 RSI: 0000200000000400 RDI: 0000000000000004
RBP: 00007f9e0e211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9e0e3d6038 R14: 00007f9e0e3d5fa0 R15: 00007ffce6fc4cd8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/10 09:23 linux-6.1.y f97f1002271b fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in kernfs_fop_write_iter
* Struck through repros no longer work on HEAD.