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INFO: rcu detected stall in sys_mkdirat (2)

Status: upstream: reported on 2026/05/01 18:50
Reported-by: syzbot+64943c92e9ed0fc050a1@syzkaller.appspotmail.com
First crash: 28d, last: 2d09h
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in sys_mkdirat 1 2 554d 593d 0/3 auto-obsoleted due to no activity on 2025/03/02 02:09
linux-5.15 INFO: rcu detected stall in sys_mkdirat 1 1 934d 934d 0/3 auto-obsoleted due to no activity on 2024/02/15 18:20
upstream INFO: rcu detected stall in sys_mkdirat ext4 net 1 3 1144d 1260d 0/29 auto-obsoleted due to no activity on 2023/07/11 04:05
upstream INFO: rcu detected stall in sys_mkdirat (2) mm 1 44 328d 529d 0/29 auto-obsoleted due to no activity on 2025/10/13 21:11
linux-5.15 INFO: rcu detected stall in sys_mkdirat (3) 1 7 15d 205d 0/3 upstream: reported on 2025/11/05 18:14
linux-5.15 INFO: rcu detected stall in sys_mkdirat (2) 1 1 456d 456d 0/3 auto-obsoleted due to no activity on 2025/06/08 06:38
android-5-15 BUG: soft lockup in sys_mkdirat 1 8 723d 775d 0/2 auto-obsoleted due to no activity on 2024/09/03 20:00

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2665 jiffies s: 18045 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: 8422 Comm: syz.3.1240 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:check_preemption_disabled+0xa/0x110 lib/smp_processor_id.c:13
Code: 7e 0a fa e9 6e ff ff ff 00 00 cc cc 00 00 cc cc 48 c7 c7 00 1b df 8a 48 c7 c6 40 1b df 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 01 6f d3 75 65
RSP: 0018:ffffc90000007868 EFLAGS: 00000082
RAX: 1ffffffff2d8a2a5 RBX: 0000000000000014 RCX: ffff88802d6ad940
RDX: 0000000000000100 RSI: ffffffff8adf1b40 RDI: ffffffff8adf1b00
RBP: 0000000000000001 R08: ffffffff8e200c2f R09: 1ffffffff1c40185
R10: dffffc0000000000 R11: fffffbfff1c40186 R12: ffffffff8c655980
R13: dffffc0000000000 R14: ffffffff96c51528 R15: 0000607f46ec4000
FS:  00007ffa7a42a6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2fe1aff8 CR3: 000000002e528000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_trace_buf_alloc+0x178/0x300 kernel/trace/trace_event_perf.c:420
 perf_trace_preemptirq_template+0x143/0x320 include/trace/events/preemptirq.h:14
 trace_irq_disable include/trace/events/preemptirq.h:36 [inline]
 trace_hardirqs_off_finish+0x13f/0x180 kernel/trace/trace_preemptirq.c:67
 irqentry_enter+0x33/0x50 kernel/entry/common.c:382
 sysvec_irq_work+0xa/0xc0 arch/x86/kernel/irq_work.c:17
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 82 22 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007ac0 EFLAGS: 00000206
RAX: 2d31d0077592f200 RBX: 1ffff92000000f60 RCX: 2d31d0077592f200
RDX: dffffc0000000000 RSI: ffffffff8a8c19a0 RDI: ffffffff8adf1b60
RBP: ffffc90000007bb0 R08: ffffffff90afd247 R09: 1ffffffff215fa48
R10: dffffc0000000000 R11: fffffbfff215fa49 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:1747 [inline]
 __hrtimer_run_queues+0x54a/0xd50 kernel/time/hrtimer.c:1811
 hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1828
 handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 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_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 3f 4e 20 f7 65 8b 05 40 c0 c9 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90003686e80 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 2d31d0077592f200
RDX: dffffc0000000000 RSI: ffffffff8a8c19a0 RDI: 0000000000000001
RBP: ffffc90003686f10 R08: ffffffff90afd247 R09: 1ffffffff215fa48
R10: dffffc0000000000 R11: fffffbfff215fa49 R12: dffffc0000000000
R13: ffffffff8cb33380 R14: ffffffff8cb33b80 R15: 1ffff920006d0dd0
 rcu_report_exp_rnp kernel/rcu/tree_exp.h:224 [inline]
 rcu_preempt_deferred_qs_irqrestore+0x885/0xc30 kernel/rcu/tree_plugin.h:567
 rcu_read_unlock_special+0x42a/0x510 kernel/rcu/tree_plugin.h:684
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 is_bpf_text_address+0x27a/0x2a0 kernel/bpf/core.c:737
 kernel_text_address+0x9c/0xd0 kernel/extable.c:125
 __kernel_text_address+0x9/0x30 kernel/extable.c:79
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:936 [inline]
 __kmalloc_node_track_caller+0xae/0x230 mm/slab_common.c:956
 kstrdup mm/util.c:61 [inline]
 kstrdup_const+0x56/0x90 mm/util.c:84
 __kernfs_new_node+0xa6/0x810 fs/kernfs/dir.c:610
 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:690
 __kernfs_create_file+0x47/0x2e0 fs/kernfs/file.c:1068
 cgroup_add_file kernel/cgroup/cgroup.c:4225 [inline]
 cgroup_addrm_files+0x7b6/0xcb0 kernel/cgroup/cgroup.c:4285
 css_populate_dir+0x159/0x3c0 kernel/cgroup/cgroup.c:1794
 cgroup_apply_control_enable+0x636/0xb00 kernel/cgroup/cgroup.c:3291
 cgroup_mkdir+0xc44/0xe30 kernel/cgroup/cgroup.c:5789
 kernfs_iop_mkdir+0x24c/0x3d0 fs/kernfs/dir.c:1221
 vfs_mkdir+0x387/0x570 fs/namei.c:4114
 do_mkdirat+0x1d8/0x440 fs/namei.c:4139
 __do_sys_mkdirat fs/namei.c:4154 [inline]
 __se_sys_mkdirat fs/namei.c:4152 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4152
 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: 0033:0x7ffa7959ce59
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:00007ffa7a42a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007ffa79815fa0 RCX: 00007ffa7959ce59
RDX: 00000000000001ff RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007ffa79632d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffa79816038 R14: 00007ffa79815fa0 R15: 00007ffc18be4e68
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/28 04:40 linux-6.1.y dcbcab9d7079 4c36e7e5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sys_mkdirat
2026/05/01 18:50 linux-6.1.y 4931e0e1673d 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sys_mkdirat
* Struck through repros no longer work on HEAD.